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Item 1. Business

2025-03-13 compared with 2024-03-25 · 592 added, 661 removed, 1482 unchanged (46% of the section changed)

We are a clinical-stage oncology company developing site-specific and novel-format antibody drug conjugates, or ADCs, enabled by our proprietary integrated cell-free protein synthesis platform, XpressCF ® , and our site-specific conjugation platform, XpressCF+ ® .

We aim to design and develop therapeutics using the most relevant and potent modalities, including ADCs, bispecific ADCs, immunostimulatory ADCs, or iADCs, dual conjugate ADCs, or ADC 2 s, and cytokine derivatives.

We are an oncology company developing site-specific and novel-format antibody drug conjugates, or ADCs, enabled by our proprietary integrated cell-free protein synthesis platform, XpressCF ® , and our site-specific conjugation platform, XpressCF+ ® .

We aim to design and develop therapeutics using the most relevant and potent modalities, including ADCs, bispecific ADCs, immunostimulatory ADCs, or iADCs, and dual conjugate ADCs, or ADC 2 s.

Our molecules are directed primarily against clinically validated targets where the current standard of care is suboptimal.

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Our mission is to transform the lives of patients by creating medicines with improved therapeutic profiles for areas of unmet need.

Our most advanced product candidate is STRO-002, or luveltamab tazevibulin, or luvelta, an ADC directed against folate receptor-alpha, or FolRα, for patients with FolRα-expressing cancers, including ovarian cancer.

In 2019, we began enrolling patients in a Phase 1 trial of luvelta that focused on ovarian and endometrial cancers.

The Phase 1 trial assessing safety, tolerability and preliminary efficacy of luvelta to treat platinum resistant ovarian cancer has been completed.

In January 2024, we reported near-final results from this Phase 1 trial, in which luvelta exhibited a manageable safety profile together with promising preliminary efficacy data in the tested patient population, as discussed in detail below.

We also presented data from Phase 1b trials assessing safety, tolerability and preliminary efficacy for the treatment of ovarian cancer with luvelta in combination with bevacizumab and for treatment of endometrial cancer.

In August 2021, luvelta was granted Fast Track designation by the U.S.

Food and Drug Administration, or FDA, for the treatment of patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer who have received one to three prior lines of systemic therapy.

We began enrolling patients in a Phase 2/3 trial of luvelta for the treatment of platinum-resistant ovarian cancer, the REFRαME-O1 study, in June 2023.

In addition, we have been offering compassionate use of luvelta to treat pediatric patients with relapsed/refractory CBFA2T3-GLIS2, or CBF/GLIS, acute myeloid leukemia, or AML, commonly known as RAM phenotype AML.

Updated compassionate use data continued to show anti-leukemic activity of luvelta in pediatric patients with relapsed/refractory CBF/GLIS AML and was presented at the 65th American Society of Hematology Annual Meeting and Exposition (ASH 2023) in December 2023.

The data showed that luvelta was well tolerated as a monotherapy agent and in combination with standard cancer therapies.

Luvelta was granted Orphan Drug Designation by the FDA in December 2022 in this pediatric patient population.

We expect to begin enrollment of a registration-directed trial of luvelta for treatment of pediatric RAM phenotype AML in the second half of 2024.

We also have two preclinical product candidates, STRO-003 and STRO-004.

These product candidates are single homogeneous ADCs directed against an anti-receptor tyrosine kinase-like orphan receptor 1, or ROR1, and tissue factor, or TF, respectively, each of which we intend to develop for the treatment of solid tumors.

We anticipate being ready to file an IND for each of STRO-003 and STRO-004 in 2024 and 2025, respectively.

Enabled through our proprietary XpressCF ® and XpressCF+ ® platforms, we have entered into multi-target, product-focused collaborations with leading pharmaceutical and biotechnology companies in the field of oncology, including an immunostimulatory antibody-drug conjugates collaboration with Astellas Pharma Inc., or Astellas, a cytokine derivatives collaboration with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, or Merck;

Our highest priority wholly owned product candidate is STRO-004.

This preclinical product candidate is a single homogeneous ADC directed against tissue factor, or TF, which we intend to develop for the treatment of solid tumors.

We anticipate submission of an Investigational New Drug Application, or IND, to the U.S.

Food and Drug Administration, or FDA, for STRO-004 in the second half of 2025.

Enabled through our proprietary XpressCF ® and XpressCF+ ® platforms, we have entered into multi-target, product-focused collaborations with leading pharmaceutical and biotechnology companies in the field of oncology, including an immunostimulatory ADCs collaboration with Astellas Pharma Inc., or Astellas, a cytokine derivatives collaboration with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, or Merck;

a B Cell Maturation Antigen, or BCMA, ADC collaboration with Celgene Corporation, or Celgene, a wholly owned subsidiary of Bristol Myers Squibb Company, New York, NY, or BMS;

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Our XpressCF ® and XpressCF+ ® platforms have also supported Vaxcyte, Inc., or Vaxcyte, focused on discovery and development of vaccines for the treatment and prophylaxis of infectious disease.

In the fourth quarter of 2023, Vaxcyte exercised its option to access expanded rights to develop and manufacture cell-free extract for use in development and manufacture of its vaccine products, among certain other rights.

We believe our XpressCF ® platform is the first and only current Good Manufacturing Practices, or cGMP, compliant and scalable cell-free protein synthesis technology that has resulted in multiple product candidates in

clinical development.

We also have a preclinical product candidate, STRO-003, rights to which we licensed to Ipsen Pharma SAS, or Ipsen, in 2024.

STRO-003 is intended to be developed for the treatment of solid tumors and we anticipate submission of an IND in connection with this program in 2025.

We believe key advantages of our cell-free protein synthesis platform over conventional biologic drug discovery and development include:

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We plan to leverage these capabilities to accelerate the discovery and development of potential first-in-class and best-in-class molecules.

The benefits of our XpressCF ® and XpressCF+ ® platforms have resulted in collaborations with leaders in the field of oncology, including Astellas, Merck, BMS and EMD Serono.

In 2022, we entered into a License and Collaboration Agreement with Astellas, for the development of immunostimulatory antibody-drug conjugates for up to three biological targets, which remains ongoing.

Our collaboration with Merck resulted in MK-1484, a selective IL-2 agonist that Merck is developing as a monotherapy and in combination with pembrolizumab for the treatment of solid tumors.

We announced the dosing of the first patient with MK-1484 in a Phase I study in the third quarter of 2022.

Our BMS collaboration yielded CC-99712, a novel ADC therapeutic directed against BCMA.

BMS elected to terminate development of CC-99712 in June 2023, whereupon rights to the product candidate reverted to us.

Finally, our collaboration with EMD Serono yielded a novel bispecific ADC product candidate targeting EGFR and MUC1, known as M1231, for which an IND submission was filed in 2020.

EMD Serono decided to terminate development of M1231 in the first quarter of 2023.

The benefits of our XpressCF ® and XpressCF+ ® platforms have resulted in collaborations with leaders in the field of oncology, including Ipsen, Astellas, Merck, BMS and EMD Serono.

In 2024, we entered into an Exclusive License Agreement with Ipsen granting Ipsen worldwide rights to develop and commercialize STRO-003.

In 2022, we entered into a License and Collaboration Agreement with Astellas for the development of immunostimulatory ADCs for up to three biological targets.

In 2024, Astellas notified us that it would not be nominating a third target program;

preclinical development of the immunostimulatory ADCs directed to the first two targets remains ongoing.

Our research collaborations with Merck, BMS, and EMD Serono all resulted in development candidate molecules that entered clinical development.

As part of our partners’ strategic portfolio review processes, each elected to terminate further clinical development of the candidate molecules following Phase 1 clinical studies.

Through December 31, 2024, we have received an aggregate of approximately $980 million in payments from all of our collaborations, which includes approximately $79 million in investments in our stock.

We intend to selectively enter into additional collaborations with partners who are seeking efficient and effective drug discovery, preclinical development and manufacturing capabilities for the creation of novel therapeutics.

We are developing luvelta for the treatment of ovarian and endometrial cancers.

In addition to the development discussed above, an expansion cohort assessing the effects of administration of prophylactic pegfilgrastim in combination with luvelta opened for enrollment in the second quarter of 2022;

interim results from this cohort were most recently presented in January 2024.

Other studies for luvelta include a trial assessing the combination of luvelta with bevacizumab for treatment of ovarian cancer and an expansion cohort for FolRα-selected endometrial cancer that opened for enrollment in the fourth quarter of 2021.

We intend to continue development of luvelta for the treatment of these indications in the future as resources permit.

Additionally, luvelta was provided to pediatric patients with CBF/GLIS AML on a compassionate use basis.

Translational work is also ongoing to support an investigational new drug, or IND, application for the initiation of a non-small cell lung cancer study, for which submission is planned in the first half of 2024.

From 2018 through February 2025, we had been developing luveltamab tazevibulin, or STRO-002 or luvelta.

In March 2025, we conducted a strategic review of our product portfolio.

Following this review, we made the strategic decision to deprioritize additional investment into luvelta development, though we continue to explore potential partnership opportunities to make luvelta available to patients who may benefit from luvelta therapy.

In December 2021, we entered into the Tasly License Agreement, as amended in April 2022, to develop and commercialize luvelta in the Greater China territory.

We believe that our collaboration with Tasly extends the opportunity to realize the potential value of luvelta through clinical development and commercialization in Greater China.

We previously were developing STRO-001, which is an ADC directed against CD74, an antigen that is highly expressed in many B cell malignancies.

We completed enrollment for STRO-001 dose escalation in a Phase 1 trial for multiple myeloma and NHL and the maximum tolerated dose of STRO-001 was identified.

In October 2021, we entered into the BioNova Option Agreement, under which BioNova was granted the right to develop and commercialize STRO-001 in Greater China.

In March 2024, BioNova notified us that it had decided to terminate both the BioNova Option Agreement and clinical development of STRO-001 in Greater China.

Following receipt of this notice, we decided to suspend development of STRO-001.

Our most advanced assets in preclinical development are STRO-003 and STRO-004.

We believe STRO-003 has the potential to be a first-in-class and best-in-class ADC targeting ROR1 and that STRO-004 has the potential to be a best-in-class ADC targeting TF.

Preclinical data suggest that both STRO-003 and STRO-004 have potent antitumor activity and potential for a differentiated safety profile.

As discussed above, our most advanced asset in preclinical development is STRO-004.

We believe STRO-004 has the potential to be a best-in-class ADC targeting TF.

Preclinical data suggest that STRO-004 has potent antitumor activity and potential for a differentiated safety profile.

Beyond these programs and collaborations, we are developing a broader pipeline of next-generation protein therapeutics using our XpressCF ® and XpressCF+ ® platforms.

Our protein engineering and chemistry efforts are focused on maximizing therapeutic indices, and our technology allows us to rapidly test our therapeutic hypothesis in significantly more product candidates than conventional protein synthesis allows in order to identify the best molecule to advance to the clinic.

Our protein engineering and chemistry efforts are focused on maximizing therapeutic indices, and our technology allows us to rapidly test our therapeutic hypothesis in significantly more product candidates than conventional protein synthesis allows, with the goal of identifying the best molecule to advance to the clinic.

We are also actively pursuing the discovery and development of other novel ADCs and next-generation ADC modalities, including iADCs, bispecific ADCs, and ADC 2 s.

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Key elements of our strategy are to:

• Advance luvelta through clinical development.

We are currently enrolling patients in a Phase 2/3 trial of luvelta for the treatment of platinum-resistant ovarian cancer, the REFRαME-O1 study.

We also expect to enroll patients in a registration-directed trial of luvelta for the treatment of pediatric RAM phenotype AML in the second half of 2024.

Given that FolRα is a clinically validated target for ovarian cancer, along with luvelta’s homogeneous design, we believe it has the potential to be a best-in-class FolRα-targeted ADC and provide benefit to a broader patient population, as well as potentially greater activity, stability and/or safety as compared to other investigational agents in development.

• Opportunistically maintain worldwide rights or pursue strategic partnerships to maximize the potential value of our pipeline.

We have assembled a management team with extensive experience in the biopharmaceutical industry, including drug discovery and development through commercialization, and our plan is to independently pursue the development and commercialization of our product candidates, to the extent possible.

As we continue to advance our products, we may opportunistically pursue additional strategic partnerships that maximize the value of our pipeline, including relationships, when possible, to potentially co-develop and co-commercialize one or more of our product candidates.

• Advance STRO-004 through clinical development.

We anticipate submission of an IND to the FDA for STRO-004 in the second half of 2025.

We intend to develop STRO-004 for the treatment of solid tumors, potentially including cervical cancer, head and neck cancer, non-small cell lung cancer, colorectal cancer, and pancreatic cancer.

Given that TF is a clinically validated target for cervical cancer, along with STRO-004’s homogeneous design and preclinical anti-tumor activity and toxicity data, we believe it has the potential to be a best-in-class TF-targeted ADC and provide benefit to a broader patient population than approved TF-targeting agents, as well as potentially greater activity, stability and/or safety as compared to other investigational agents in development.

• Pursue strategic partnerships to maximize the potential value of our pipeline.

We have assembled a management team with extensive experience in the biopharmaceutical industry, including drug discovery and development through commercialization, and our plan is to independently, or through partnerships, pursue the development and commercialization of our product candidates, to the extent possible.

As we continue to advance our product candidates, we may opportunistically pursue additional strategic partnerships that maximize the value of our pipeline, including relationships, when possible, to potentially co-develop and co-commercialize one or more of our product candidates.

• Develop a diverse pipeline of novel product candidates with optimized therapeutic profiles.

We intend to continue to build a broad pipeline of optimally designed, next-generation protein therapeutics, initially for cancer, using our XpressCF ® platform.

We intend to continue to build a broad pipeline of optimally designed, next-generation protein therapeutics, initially for cancer, using our XpressCF ® and XpressCF ® platforms.

Our cell-free-based protein synthesis system enables the rapid and systematic evaluation of protein structure-activity relationships, which we believe will accelerate the discovery and development of molecules.

We aim to take advantage of the most potent modalities, focusing primarily on ADCs, iADCs, bispecific ADCs and ADC 2 s, to create drugs that are directed primarily against clinically validated targets where the current standard of care is suboptimal.

• Strategically pursue additional collaborations to broaden the reach of our XpressCF ® platform.

To maximize the value of our XpressCF ® platform technology, we have entered into multi-target, product-focused collaborations with leaders in the field of oncology, including an iADC collaboration with Astellas, a cytokine derivatives collaboration with Merck, a BCMA ADC collaboration with BMS and a MUC1-EGFR ADC collaboration with EMD Serono.

We intend to selectively enter into additional collaborations with partners who are seeking efficient and effective drug discovery and manufacturing capabilities for the development of novel therapeutics.

• Strategically pursue additional collaborations to broaden the reach of our XpressCF ® and XpressCF+ ® platforms.

To maximize the value of our XpressCF ® and XpressCF+ ® platform technology, we have entered into multi-target, product-focused collaborations with leaders in the field of oncology, including an iADC collaboration with Astellas, a cytokine derivatives collaboration with Merck, a BCMA ADC collaboration with BMS and a MUC1-EGFR ADC collaboration with EMD Serono.

We intend to selectively enter into additional research collaborations with partners who are seeking efficient and effective drug discovery and manufacturing capabilities for the development of novel therapeutics.

We intend to retain, to the extent possible, certain development and commercial rights to maximize the future potential value of product candidates discovered and developed using our XpressCF ® platform.

Cancers Remains a Major Unmet Medical Need

• Strategically position our XpressCF ® platform as a preferred alternative to conventional methods for manufacturing proteins for both research and clinical use.

To further enhance the value of our XpressCF ® platform, we intend to explore granting nonexclusive access to our technology platform to potential licensees who are seeking access to efficient and effective drug discovery and manufacturing solutions, particularly those that can benefit from our XpressCF+ ® conjugation technology.

Cancers Remain a Major Unmet Medical Need

Cancers are the second leading cause of mortality in the United States and the leading cause of death for those under 65 years of age.

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Over the last twenty years, new paradigms of cancer research and treatment have emerged to address the limitations of existing treatments.

Some of the most promising new approaches involve biologic therapies, including Antibody Drug Conjugates, or ADCs.

ADCs have shown promise over the last decade with twelve marketed products in the United States and over 200 ADC candidates investigated in the clinic.

Some of the most promising new approaches involve biologic therapies, including ADCs.

ADCs have shown promise over the last decade with twelve currently marketed products in the United States and over 200 ADC candidates investigated in the clinic.

ADCs use the foundation of monoclonal antibodies and small molecule drugs by targeting the delivery of chemotherapeutics to the tumor.

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The following diagram shows the component parts of an ADC.

Currently, there are more than 200 ADCs being investigated in clinical development.

Currently, there are approximately 250 ADCs being investigated in clinical development.

Kadcyla and Adcetris were the first of the new generation of ADCs to be approved for the treatment of specific subsets of breast cancer and lymphoma, respectively.

Several more ADCs are currently on the market in the U.S.:

Besponsa, Mylotarg, Polivy, Zynlonta, and Zevalin were approved for the treatment of specific subsets of leukemia and lymphoma;

Besponsa, Mylotarg, Polivy, and Zynlonta were approved for the treatment of specific subsets of leukemia and lymphoma;

Padcev was approved for the treatment of bladder and urinary tract cancers;

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Tivdak was approved for the treatment of cervical cancer;

and mirvetuximab soravtansine (Elahere ® ) was approved for the treatment of ovarian cancer.

Elahere was approved for the treatment of ovarian cancer;

and Datroway was approved for the treatment of a subset of breast cancer in January 2025.

These approved therapies demonstrate that ADCs have an emerging role in the armamentarium of cancer therapeutics.

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We believe that safer ADCs can be developed by utilizing non-natural amino acids that enable state-of-the-art chemistries to ensure that the warhead is not prematurely released.

In addition, linker chemistries that rely on proteinases preferentially expressed in the tumor such as cathepsin and B-Glucuronidase, can provide more tumor specific release of the active catabolites and a resulting better safety profile.

In addition, linker chemistries that rely on proteinases preferentially expressed in the tumor such as cathepsin and β-Glucuronidase, can provide more tumor specific release of the active catabolites and a resulting better safety profile.

• Mechanism of Action of Cytotoxin Payloads.

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Despite the progress made, serious adverse events and efficacy challenges remain.

For example, upon prolonged treatment with DXd-based ADCs, a small but significant fraction of patients develop ILD.

For example, upon prolonged treatment with DXd-based ADCs, a small but significant fraction of patients develop interstitial lung disease, or ILD.

This adverse event is observed independent of the tumor antigen targeted by the ADC.

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Exatecans are, in general, less potent inducers of tumor cell death compared to tubulin inhibitors.

Therefore, low copy number tumor antigens and/or antigens with low internalization rates may be poor targets for extecan-based ADCs due to low potency.

Dual conjugations to enable iADC and ADC 2 modalities to address current limitations of extecan-based ADCs and to optimize the therapeutic index, or TI

Therefore, low copy number tumor antigens and/or antigens with low internalization rates may be poor targets for exatecan-based ADCs due to low potency.

Dual conjugations to enable iADC and ADC 2 modalities to address current limitations of conventional ADCs and to optimize the therapeutic index, or TI

XpressCF ® enables the incorporation of non-natural amino acids into antibody sequences and results in site specific conjugation of drug payloads.

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In addition to immune modulators, additional payloads can be incorporated into our dual conjugation approach.

These ADC 2 payloads are focused on targets that are upregulated tumors that do not respond well to existing therapies.

Our goal is to provide more durable responses in hard-to-treat tumors by combining two payloads that may offset resistance mechanisms.

Cytokine-Based Immuno-Oncology Therapeutics

Cytokines are small biologically active proteins that play an essential role in immune cell function.

Cytokines are important for cell-to-cell communication and are responsible for controlling immune cell growth and differentiation.

Recombinant human cytokines were among the first biotechnology products engineered for therapeutic use and, in the field of oncology, cytokines that stimulate the immune system to attack cancer cells have been viewed as a potential new approach.

Certain cytokines play a central role in T cell function, contributing to the careful balance between helpful and harmful immune responses.

These can be powerful activators of the immune system but can also suppress immune responses through certain specialized T cells that have suppressive functions.

A previously approved cytokine therapeutic Proleukin ® had shown therapeutic benefit in a small number of cancer patients, but its therapeutic use was limited due to toxicity.

Scientists at other companies have focused research on finding ways to modify cytokines so as to reduce toxicity while maintaining therapeutic benefit.

The observed efficacy of a modified cytokine, in combination with an immune checkpoint inhibitor, indicates the potential of this new approach.

In light of these data and our prior research into cytokines, we commenced a cytokine-based research

program using our XpressCF ® and XpressCF+ ® platform technologies to engineer cytokines aimed at better exposure and tolerability profiles.

Our collaboration with Merck focused on developing cytokine derivatives yielded an IL-2 derivative that entered Phase 1 in 2022.

We believe that recent advances in immuno-oncology combined with new protein engineering technologies create opportunities to identify novel cytokine-based therapeutics with superior therapeutic indexes.

These ADC 2 payloads are focused on validated targets that are upregulated in tumors that do not respond well to existing therapies.

Our goal is to provide more durable responses in hard-to-treat tumors by combining two payloads that may overcome the onset of resistance towards single payload ADCs reported in clinical meetings.

The therapeutic benefit of combining microtubule inhibitors, or MTIs, with exatecan-based ADCs has been demonstrated in the clinic by admixing of two ADCs with either an MTI or exatecan-based payload.

We believe that the use of payloads that induce tumor cell death via different mechanism of action may reduce or delay development of resistance to either one of the payloads.

We are also exploring dual-payload concepts combining inhibitors of DNA repair with exatecan-based payloads.

We believe that blocking alternative signaling pathways by combining DNA Double-strand repair inhibitors, or DDRis, with exatecan-based payloads is a promising dual payload approach for BRCA1/2 mutant tumors.

Our Proprietary XpressCF ® Platform

While ADCs, iADCs, ADC 2 s and engineered cytokines hold significant promise, drug developers working with these complex biologics face significant design and development challenges.

While ADCs, iADCs, and ADC 2 s hold significant promise, drug developers working with these complex biologics face significant design and development challenges.

Optimizing these complex biological structures is a challenging, trial and error process that requires the refinement of several properties in tandem.

This iterative process is cumbersome and fraught with significant limitations.

As a result, the drug candidate nominated for development is often plagued by inefficient design properties, which then translates to a suboptimal therapeutic index when investigated in the clinic.

As a result, the drug candidate nominated for

development is often plagued by inefficient design properties, which then translates to a suboptimal therapeutic index when investigated in the clinic.

Our XpressCF ® platform seeks to address these significant shortcomings.

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By decoupling the production of the cell-free extract from the production of the protein, we are able to stockpile large quantities of cell-free extract from which we are able to manufacture a wide variety of proteins without the need to generate individual cell lines, including cytokine-based immuno-oncology therapeutics, ADCs, iADCs and bispecific antibodies.

Additionally, our dual conjugation ADC 2 technology could enable “mixed

payload” ADCs that combine two distinct small molecules with different pharmacologies onto a single antibody.

Additionally, our dual conjugation ADC 2 technology could enable “mixed payload” ADCs that combine two distinct small molecules with different pharmacologies onto a single antibody.

• Ability to Incorporate Non-Natural Amino Acids.

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• Absence of Fc-gamma Receptor Binding.

Antibodies produced using the XpressCF ® platform have not been shown to bind the Fc-gamma receptor, and therefore are not subject to Fc-gamma mediated uptake by alveolar macrophages, which we believe results in reduced nonspecific payload release in the lung, reducing the potential for ILD.

Antibodies produced using the XpressCF ® platform have not been shown to bind the Fc-gamma receptor, and therefore are not subject to Fc-gamma mediated uptake

by alveolar macrophages, which we believe results in reduced nonspecific payload release in the lung, reducing the potential for ILD.

• Faster Cycle Time.

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We have examples where changing just one of these parameters can significantly impact the safety, efficacy and stability of the ADC.

Further, we have

demonstrated the ability to introduce more than eight non-natural amino acids into a single antibody structure, without impacting the expression levels of engineered antibodies, permitting ADCs with a DAR of greater than eight.

Further, we have demonstrated the ability to introduce more than eight non-natural amino acids into a single antibody structure, without impacting the expression levels of engineered antibodies, permitting ADCs with a DAR of greater than eight.

Most conventional conjugation methods are limited by a DAR of eight, due to the availability of only eight interchain cysteines, which are used for conjugation with conventional methods.

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Protein therapeutics can encounter obstacles, or even fail, during the transition from research cell lines to cGMP cell lines appropriate for clinical development and commercialization.

Our XpressCF ® platform can rapidly produce different protein types from a single proprietary extract, which can be scaled for discovery, development and ultimately, we believe, commercialization of cytokine-based immuno-oncology therapeutics, ADCs, iADCs, bispecific ADCs and ADC 2 s.

Our XpressCF ® platform can rapidly produce different protein types from a single proprietary extract, which can be scaled for discovery, development

and ultimately, we believe, commercialization of cytokine-based immuno-oncology therapeutics, ADCs, iADCs, bispecific ADCs and ADC 2 s.

• Manufacturable Dual Conjugations.

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Our currently active collaborations include:

• Merck Program.

We have granted Merck the right to develop MK-1484, a selective IL-2 agonist in clinical studies as a monotherapy and in combination with pembrolizumab for the treatment of solid tumors.

• Ipsen Relationship.

We have granted Ipsen the right to develop and commercialize STRO-003, an ADC targeting ROR1.

• Astellas Collaboration.

The collaboration and license agreement with Astellas covers the discovery and development of immunostimulatory antibody-drug conjugates for up to three biological targets.

The collaboration and license agreement with Astellas covers the discovery and development of immunostimulatory antibody-drug conjugates for two biological targets.

• Vaxcyte Relationship.

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Our Product Candidates

Luveltamab tazevibulin (luvelta), an ADC Directed Against the Target Folate Receptor-Alpha (FolRα)

We are developing luveltamab tazevibulin, or luvelta, an optimally designed ADC directed against the cancer target FolRα, initially focused on ovarian and endometrial cancers.

Luvelta was designed and optimized for an improved therapeutic index by placing a precise number of linker-warheads at four specific locations within the antibody using our proprietary XpressCF+ ® platform.

We initiated a Phase 2/3 trial to assess the efficacy of luvelta for the treatment of platinum resistant ovarian cancer, the REFRAME-O1 study, in June 2023.

Phase 1 trial enrollment, focused on ovarian and endometrial cancers, began in March 2019.

We reported a near-final dataset in January 2024.

Based on such reported data, luvelta exhibited a manageable safety profile and promising preliminary efficacy data.

Both the dose-escalation and the dose-expansion portions of the Phase 1 trial were fully enrolled for assessment of the efficacy, safety, and tolerability of luvelta at dose levels of 4.3 and 5.2 mg/kg.

Additionally, a combination cohort in ovarian cancer, assessing the combination of luvelta with bevacizumab, opened for enrollment in December 2021, and an expansion cohort for FolRa-selected endometrial cancer opened and began enrolling patients in the fourth quarter of 2021.

Interim results from the endometrial cohort demonstrated encouraging preliminary anti-tumor activity in FolRα-selected patients, defined by a tumor proportion score, or TPS, of >25% FolRα expression, with a safety profile that was consistent with prior data in patients with platinum-resistant ovarian cancer, and were presented at the 2023 European Society for Medical Oncology, or ESMO, Congress in October 2023.

An expansion cohort assessing the effects of administration of prophylactic pegfilgrastim in combination with luvelta opened for enrollment in the second quarter of 2022;

interim results from this cohort were also presented in January 2023.

Interim results from the combination study of luvelta with bevacizumab for treatment of ovarian cancer and updated results from the cohort assessing the combination of luvelta with pegfilgrastim were presented in January 2024.

In August 2021, we were granted Fast Track designation for luvelta by the FDA for the treatment of patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer, who have received one to three prior lines of systemic therapy.

In December 2021, we entered into a collaboration and exclusive license agreement with Tasly to develop and commercialize luvelta in Greater China.

Luvelta has been provided through compassionate use to pediatric patients with relapsed/refractory CBF/GLIS AML, which data were presented at ASH 2022 and ASH 2023.

The data showed that luvelta was well tolerated as a monotherapy agent and in combination with standard cancer therapies.

In December 2022, luvelta was granted Orphan Drug Designation by the FDA for this pediatric indication.

Ovarian Cancer Overview

Ovarian cancer is the most common cause of cancer death from gynecologic tumors in the United States, and the fifth most common cause of cancer death in women.

In the United States alone, the American Cancer Society estimates that 19,680 new cases of ovarian cancer would be diagnosed in 2024, and approximately 12,740 women would die of this disease.

Given that early stages of the disease cause minimal, nonspecific symptoms or are asymptomatic, approximately 75% of patients with ovarian cancer are diagnosed as stage III and IV, for which the prognosis is poor.

Standard pre- or post-operative chemotherapy for ovarian cancer is combination therapy with a platinum compound and a taxane, for example, carboplatin and paclitaxel, with or without bevacizumab which achieves a complete or partial response in between 70% to 80% of patients.

Increasingly, PARP inhibitors are being used in the maintenance setting.

Patients who are refractory or resistant to platinum-based treatments are then treated with a host of additional palliative chemotherapeutic agents, each showing only marginal benefit with response rates to single agent chemotherapy of 10-12% and progression free survival of 3-4 months.

This represents a significant unmet need.

Endometrial Cancer Overview

There is also a significant unmet need in the treatment of recurrent or metastatic endometrial cancer.

In the United States alone, the American Cancer Society estimated 67,800 new cases of endometrial cancer, which is cancer of the uterus, in 2024, and that approximately 13,250 women would die of this disease.

First-line treatment for stage III/IV disease is commonly paclitaxel/carboplatin.

Recently, the combination of lenvatinib and pembrolizumab was approved for the treatment of patients with advanced, metastatic endometrial cancer who have disease progression following prior systemic therapy with a platinum doublet.

With the lack of available therapies for patients who progress after standard of care therapies, long-term survival prospects are poor and novel treatments offering even a modest improvement in progression-free survival or overall survival, or OS, may be considered for expedited regulatory approval.

Pediatric AML CBFA2T3-GLIS2 (CBF/GLIS) Phenotype Overview

There remains a significant unmet need in the treatment of CBF/GLIS AML in pediatric patients.

The CBF/GLIS subtype of AML is a rare, aggressive form of AML that typically affects pediatric patients with a median age of 1.5 years.

The prevalence of CBF/GLIS AML is 1%-3% in childhood AML, and in recent studies the incidence was determined to be 1.3%-1.8% of pediatric AML patients.

The prognosis for this disease is grim, with a 5-year OS of 15-30%.

The first-line treatment for this disease is chemotherapy with a goal of reducing disease burden to the point that the patient can receive a bone marrow transplant.

While a bone marrow transplant is intended to be curative, most patients eventually relapse with poor treatment outcomes.

Patients who are refractory to primary chemotherapy or who relapse following bone marrow transplant have no additional treatment options and also have poor treatment outcomes.

Given the lack of treatment options for these patients, a novel treatment that offers an opportunity for these patients to become eligible for bone marrow transplantation may be considered for expedited regulatory review.

Our Solution, luveltamab tazevibulin (luvelta)

Luvelta targets FolRα, a surface protein with limited expression on normal tissue and overexpressed in multiple cancers, including ovarian cancer, which makes FolRα a promising ADC approach.

Luvelta employs a cleavable linker that releases a cytotoxic drug inside tumor cells, while being stable and resistant to cleavage in general circulation.

The cytotoxic drug used in luvelta is our proprietary hemiasterlin moiety.

From a safety perspective, we designed luvelta to have what we believe to be the optimal potency-to-safety ratio.

We therefore rationally selected a homogenous ADC with an optimized DAR of four.

Based on preclinical findings, we believe our efficient homogeneous design of luvelta could provide anti-tumor activity, stability, and safety with the potential to minimize off-target damage and improve clinical benefit.

We believe an improved therapeutic index could differentiate luvelta from conventional technology for the treatment of ovarian cancer and endometrial cancer.

To test this, we have created a benchmark FolRα-targeting surrogate molecule based on conventional technology that has a heterogeneous ADC, with a similar DAR, utilizing a DM4 linker-warhead.

We have tested this benchmark molecule against luvelta in multiple preclinical models.

However, additional preclinical and clinical testing will be needed to determine the safety and efficacy of luvelta and to obtain regulatory approval, if ever obtained.

Clinical Development Plan

Our first Phase 1 trial for luvelta was an open-label study evaluating luvelta as a monotherapy for patients with ovarian and endometrial cancers.

This trial was being conducted in two-parts, dose escalation and dose expansion.

We began enrolling ovarian cancer patients in March 2019, with updated data for the completed dose escalation cohort reported in December 2020 and May 2021.

The primary objectives of the clinical trial are to determine the safety and tolerability profile, to define the recommended Phase 2 dose level and interval, and to evaluate preliminary anti-tumor activity.

Our secondary objectives are to characterize human pharmacokinetics and additional safety, tolerability, and efficacy measures.

We initially enrolled adult patients with advanced and/or refractory ovarian cancer, for whom no suitable treatment exists.

These patients are considered to have incurable disease and need repeated courses of life-prolonging and palliative treatment.

The initial Phase 1 trial enrolled ovarian cancer patients regardless of their FolRα expression levels.

These ovarian cancer patients were enrolled in a dose escalation cohort, with luvelta administered on day one of a 21-day cycle.

Since anti-tumor activity was observed during the fully enrolled dose escalation portion of the Phase 1 trial, we initiated enrollment of patients in the dose expansion portion of this clinical study in January 2021 and are treating less heavily pre-treated ovarian cancer patients.

The dose expansion portion of this Phase 1 study of luvelta has been completed.

In May 2021, we announced data from the dose-escalation portion of our ongoing Phase 1 clinical trial of STRO-002 in patients with ovarian cancer.

The dose-escalation portion of the trial was fully enrolled with 39 patients in August 2020.

Patients were heavily pre-treated and had a median of six prior lines of therapy, including standard of care platinum-based regimens, bevacizumab, PARP inhibitors, and checkpoint inhibitors.

The dose-escalation portion of the Phase 1 trial included 34 patients treated with clinically active dose levels, 2.9 mg/kg or higher, of which 31 patients had post-baseline scans and were evaluable for RECIST response.

At the data cutoff of April 23, 2021, results out of 31 evaluable patients included:

• 10 patients (32%) met RECIST criteria for response, of which, one patient achieved a complete response, or CR, and nine patients achieved a partial response (four confirmed partial responses and five unconfirmed partial responses).

• For the five confirmed responders (1 CR and 4 confirmed partial responses), the median duration of response, or DOR, was 5.8 months (95% CI:

2.0, not evaluable).

• Median study follow-up was 8.4 months and median progression-free survival (PFS) was 7.2 months (95% CI:

• 86% of treatment-emergent adverse events, or TEAEs, were Grade 1 or 2.

The most common Grade 3 and 4 AEs were neutropenia (64%), arthralgia (13%), fatigue (10%), neuropathy (8%), and abdominal pain (8%), all of which were managed with standard medical treatment, dose reductions, or dose delays.

• Dose limiting toxicities, or DLTs, were observed at higher dose levels in two patients – at 6.0 mg/kg (Grade 2 neuropathy/Grade 3 arthralgia) and at 6.4 mg/kg (Grade 3 bone pain).

Based on the above results, we identified dose levels of 4.3 and 5.2 mg/kg to study in the dose-expansion portion of the Phase 1 trial.

For the dose-expansion portion, we dosed the first patient in January 2021 and treated less heavily pre-treated ovarian cancer patients.

We reported near-final data in January 2024.

We also initiated an exploratory dose expansion cohort of 15 patients to assess the safety of treatment with luvelta at 5.2 mg/kg in combination with prophylactic pegfilgrastim, and interim results from this cohort were also presented in January 2023 and January 2024.

The dose-expansion cohort for ovarian cancer fully enrolled 44 patients, who had experienced up to three prior lines of therapy and were randomized into dose levels starting at 4.3 mg/kg (N=23) and 5.2 mg/kg (n=21).

81% of the patients were platinum-resistant, and 66% and 82% of the patients had been treated previously with bevacizumab and PARP inhibitors, respectively.

The patients were also assessed for FolRα expression levels, which were calculated using TPS correlated with higher response rates.

We have identified TPS as a potentially appropriate scoring algorithm for luvelta with respect to the biomarker enrichment strategy.

Of the 44 patients in this cohort, 9 had a TPS score of less than or equal to 25%, while 35 had a TPS score of greater than 25%.

Of these 35 patients, as of the data cutoff date of November 8, 2022, 32 had at least one post-baseline scan, and therefore were evaluable for RECIST v1.1 responses.

The results demonstrated that luvelta provided substantial clinical benefit in FolRα-selected patients, defined by TPS of >25%, with a 37.5% overall response rate (ORR), median DOR of 5.5 months, and median PFS of 6.1 months, regardless of starting dose.

Results also demonstrated the higher starting dose of 5.2 mg/kg provided greater patient benefit compared to the lower starting dose of 4.3mg/kg.

FolRα-selected patients account for approximately 80% of the patient population in advanced ovarian cancer, as represented in the patient stratification in the Phase 1 study.

In particular:

• Patients who were FolRα-selected, defined by TPS >25%, regardless of starting dose, demonstrated an ORR of 37.5% (n=32) with a median DOR of 5.5 months (n=12) and a median PFS of 6.1 months (n=35).

• Estimated targeted luvelta patient population is approximately 80% of advanced ovarian cancer patients based on pooled Phase 1 biomarker data.

• Luvelta demonstrated a FolRα-dependent response, with patients who were unselected for FolRα (TPS ≤25%) demonstrating an 11.1% ORR (n=9) with a median DOR of 2.9 months (n=1) and a median PFS of 3.8 months (n=9).

• FolRα-selected patients given the 4.3 mg/kg dose of luvelta demonstrated an ORR of 31.3% (n=16), a median DOR of 13 months (n=5) and a median PFS of 6.1 months (n=19).

• Luvelta, when given to FolRα-selected patients at a starting dose of 5.2 mg/kg, provided greater patient benefit than a starting dose of 4.3 mg/kg, with the 5.2 mg/kg dose of luvelta demonstrating an ORR of 43.8% (n=16), a median DOR of 5.4 months (n=7) and a median PFS of 6.6 months (n=16).

Safety signals from the 44 patients at the 5.2 mg/kg and 4.3 mg/kg starting dose levels, were consistent with data from the dose-escalation cohort, including:

• No qualitatively new safety signals were observed in the dose-expansion cohort, including the absence of meaningful ocular or lung toxicity signals or complications.

• Neutropenia was the leading TEAE that resulted in a treatment delay or a dose reduction.

The majority of the cases of neutropenia were generally asymptomatic and resolved with a one-week dose delay or, in other cases, with standard medical treatment, including the use of G-CSF.

• Arthralgia was the second most common Grade 3 or higher, or Grade 3+, TEAE and second most common TEAE leading to dose reduction.

• There were limited observed cases of febrile neutropenia, including one Grade 5 event at the 5.2 mg/kg starting dose level and one Grade 3 event at the 4.3 mg/kg starting dose level.

The trial protocol was subsequently updated to require dose reduction for Grade 4 neutropenia.

In 2022 we initiated an exploratory cohort, or cohort C, of 15 patients to assess the safety of treatment with luvelta at 5.2 mg/kg in combination with prophylactic pegfilgrastim and presented preliminary data from 10 patients from this cohort in January 2023.

In January 2024, we announced updated data from this cohort based on 16 patients.

In particular:

• Grade 3+ neutropenia was reduced from 66.7% to 6.3%, resulting in a 90.6% decrease in Grade 3+ neutropenia rates at the first cycle of luvelta (p=0.0002);

Grade 3 neutropenia was reduced from 71.4% to 18.8%, resulting in a 73.7% decrease in Grade 3+ neutropenia rates at the first and second cycle (p=0015)

• Overall Grade 3+ neutropenia was reduced from 76.2% to 37.5%.

In January 2024, we presented an aggregated data set from of our Phase I trials of luvelta.

This data set included data from all ovarian cancer patients treated with luvelta as a monotherapy in Phase 1 studies, regardless of FolRα expression levels, dose level of luvelta, or platinum sensitivity or resistance, corresponding to a total of 99 patients, of which 92 were RECIST-evaluable, with 21% platinum sensitive patients and 78% platinum refractory patients.

Patients received a median of three prior lines of therapy.

There were 72% of the patients that had experienced prior bevacizumab therapy and 70% had been treated with a PARP inhibitor.

These patients were not selected for FolRα expression levels and were treated at starting dose levels ≤2.9 mg/kg, 4.3 mg/kg, 5.2 mg/kg or ≥5.6 mg/kg.

The safety profile of luvelta from these aggregated data was shown to be manageable, with a low rate of discontinuation of treatment resulting from neutropenia.

The predominant TEAE, was neutropenia, encompassing neutropenia, febrile neutropenia, and decreased neutrophil count, with 69.7% patients reporting any grade neutropenia and 64.6% patients reporting Grade 3 or higher neutropenia.

Neuropathy and arthralgia were the other most commonly reported significant TEAEs, with 57.6% and 16% of patients reporting any grade and Grade 3 or higher arthralgia, respectively, and 44% and 7% patients reporting any grade and Grade 3 or higher neuropathy, respectively.

The observed neutropenia was primarily uncomplicated, with less than 5% incidence of febrile neutropenia.

Neutropenia and arthralgia each led to discontinuation of treatment in 1.5% of patients.

Neuropathy led to discontinuation of treatment in 2.9% of patients.

There were six patients that experienced grade 5 safety events on study, with one such event assessed as probably luvelta related and the remainder assessed as unrelated to luvelta.

We also presented a subset of the aggregated data from our Phase 1 trials of luvelta for which 43 patients with platinum resistant ovarian cancer selected for FolRα TPS ≥25%, or tumors with ≥25% of the tumor cells expressing FolRα at any level of staining intensity, were treated with 4.3 mg/kg or 5.2 mg/kg doses of luvelta, corresponding to all patients treated in phase 1 studies that would be eligible for enrollment in the REFRαME-O1 registrational study.

The ORR observed for this subset population was 28%, with a DOR of 5.7 months and PFS of 5.8 months.

Based on the data from our Phase 1 program, we selected FolRα expression TPS ≥25% as the target eligibility cutoff or threshold for further study in clinical development of luvelta.

We estimate that approximately 80% of the platinum resistant ovarian cancer patients would be eligible for luvelta treatment based on this TPS ≥25% threshold for FolRα expression .

Additionally, we opened for enrollment a Phase 1 trial to assess the combination of STRO-002 and bevacizumab for treatment of ovarian cancer in December 2021 and presented initial preliminary results of this study in January 2024.

Safety signals from this study were generally consistent with those previously reported and the combination treatment with luvelta and bevacizumab demonstrated clinical activity in treated patients regardless of their FolRα expression status.

We also began enrolling patients in an expansion cohort for FolRα-selected endometrial cancer in the fourth quarter of 2021 and presented initial preliminary results from the study at the 2023 ESMO Congress in October 2023.

In this trial, luvelta showed encouraging preliminary anti-tumor activity in FolRα-selected patients, defined by a TPS of >25% FolRα expression, and the safety profile was consistent with prior data in patients with platinum-resistant ovarian cancer.

We expect to present updated results from the bevacizumab combination study in 2024.

Further, we plan to submit an IND for the treatment of NSCLC with luvelta in the first half of 2024.

In addition to the Phase 1 studies discussed above, we initiated a Phase 2/3 study, the REFRαME-O1 study, of luvelta for the treatment of platinum-resistant ovarian cancer in June 2023.

This study comprises two parts;

in Part 1, we anticipate enrolling 50 patients randomized 1:1 to two different doses of luvelta, either 4.3 mg/kg or 5.2 mg/kg plus prophylactic pegfilgrastim for two cycles, followed by a reduction to 4.3 mg/kg.

After proceeding to Part 2 of the study, the non-optimized dose of luvelta will be dropped and approximately 516 patients will be randomized 1:1 to the selected luvelta dose or investigators’ choice of chemotherapy.

The protocol will include an optional interim analysis for ORR and DOR to support a potential application for accelerated approval, and the endpoints that will be assessed for a potential full approval are PFS and OS.

The REFRαME-O1 study patient population includes those with platinum-resistant ovarian cancer, one to three lines of prior treatment and tumors that express FolRα at TPS ≥25%, and excludes primary platinum refractory patients and those with Eastern Cooperative Oncology Group Performance Status, or ECOG PS, of 0-1.

We announced the initiation of Part 1 of the REFRαME-O1 study in June 2023 and the study is ongoing.

We anticipate that Part 1 will be fully enrolled in the first half of 2024.

We are also seeking to develop luvelta for the treatment of CBF/GLIS AML in pediatric patients.

Initial access to luvelta in this indication has been provided through compassionate use.

Initial data on the anti-leukemic activity of luvelta in 17 pediatric patients with relapsed/refractory CBF/GLIS AML was presented at ASH 2022 and updated at ASH 2023, including data from eight additional patients.

The ASH 2023 presentation included results from 25 pediatric patients with relapsed/refractory CBF/GLIS subtype AML treated with luvelta at doses up to 4.3 or 5.2mg/kg every two to four weeks for a DOR of 15.9 weeks (3-73.1), with 68% of patients receiving at least five doses.

Luvelta was well-tolerated as a monotherapy agent and in combination with standard of care therapies.

Of the 25 treated patients, 19 had ≥5% blasts, consideredmorphologic disease, or MD, and 8 had <5% blasts, considered sub-morphologic disease, or SMD.

Collective results show that treatment with luvelta produced clinically meaningful and durable responses across a broad range of patients in various settings, including in patients with or without prior stem cell transplant and in monotherapy or in combination with cytotoxic therapy.

A complete remission, or CR, or complete remission with partial hematologic recovery, or CRh, was observed in 8 out of 19 (42%) patients with ≥5% blasts treated with luvelta, with 5 out of 8 CR/CRh patients reaching a minimal residual disease, or MRD,-negative CR (63%).

Six out of eight patients with <5% blasts experienced an MRD-negative CR (75%).

In the next phase of luvelta development for the treatment of CBF/GLIS AML in pediatric patients, we expect to initiate enrollment in a registration-enabling trial, REFRαME-P1, in the second half of 2024.

In the first part of the study, patients will be randomized between two doses of luvelta, 3.5 mg/kg and 4.3 mg/kg, to identify an optimized dose.

Following selection of the optimized dose, we plan to test the optimized dose in approximately 18 patients with relapsed/refractory CBFA2T3::GLIS2 AML having ≥5% bone marrow involvement with leukemic blasts.

Key endpoints are planned to be CR rate, MRD-negative response rate, event-free survival, or EFS, release-free survival, or RFS, OS, safety, and pharmacokinetics.

STRO-003, An ADC Directed Against ROR-1

In 2022, we nominated STRO-003 for further development.

STRO-003 is a ROR1-targeting ADC for the treatment of ROR1-expressing solid tumors, including triple negative breast cancer, or TNBC, NSCLC, and ovarian cancer.

STRO-003 is an anti-ROR1 human IgG1 antibody conjugated using our XpressCF+ ® platform technology to a cleavable DBCO-PEGylated β-glucuronidase-exatecan linker-payload, at a DAR of approximately eight.

Currently, there are no therapeutics approved that specifically target ROR1, although there is one ROR1-targeting ADC, zilovertamab vedotin, or ZV, also known as MK-2140, or VLS-101, in Phase 2 testing targeting DLBCL, mantle cell lymphoma, or MCL, NSCLC, and breast cancer.

Based on preclinical in vitro and in vivo data, we believe that STRO-003 has the potential for an improved therapeutic index compared to ZV.

We believe these features present a unique opportunity for clinical development of STRO-003 to address unmet medical needs in hematological malignancies, ovarian cancer, TNBC and NSCLC.

We believe STRO-003 has been precisely designed and optimized to provide the potential for a best-in-class ADC targeting ROR-1.

Our proprietary non-natural amino acid, which provides the substrate for conjugation to our proprietary β-glucuronidase cleavable exatecan linker warhead, have been placed at what we believe are the optimal sites in the amino acid sequence of our high affinity anti-ROR1 antibody, resulting in enhanced performance and stability in preclinical in vitro and in vivo models.

These models also suggest that our β-glucuronidase cleavable linkers may provide greater tumor specificity and enhanced tolerability relative to a

protease-cleavable linker delivering an exatecan payload.

In particular, in a non-human primate safety study, we did not observe neutropenia, ocular toxicity signals or lung toxicity signals even in the highest dose cohort for STRO-003.

Finally, our preclinical testing has shown that the exatecan payload delivered by STRO-003 elicits potent tumor cell killing, bystander activity and immunogenic cell death, which we believe may provide meaningful clinical benefit to patients.

STRO-003 Business Opportunity

We believe ROR1 is a favorable target for an ADC due to its limited normal tissue expression, as well as its prevalence in solid tumors and B cell malignancies, including CLL, DLBCL, MCL, TNBC, NSCLC, and ovarian cancer.

Its expression is correlated with poor prognosis in different cancers.

Currently, there are no approved therapeutics that specifically target ROR1, but it is a target of increasing interest with several clinical-stage ADCs in development, including ZV (Phase 2), NBE-002 (Phase 1), and CS5001 (Phase 1).

STRO-004, An ADC Directed Against Tissue Factor

We have recently nominated STRO-004 for further development.

Our lead developmental asset is STRO-004.

STRO-004 is a TF-targeting ADC for the treatment of TF-expressing solid tumors, potentially including cervical, lung and breast cancer.

STRO-004 is an anti-TF human IgG1 antibody conjugated using our XpressCF+ ® platform technology to a cleavable DBCO-PEGylated β-glucuronidase-exatecan linker-payload, at a DAR of approximately four.

There is an approved ADC targeting TF, TIVDAK ® , developed by Seattle Genetics and GenMab A/S, which is approved for the treatment of recurrent or metastatic cervical cancer.

In preclinical in vitro and in vivo studies benchmarking STRO-004 against a TIVDAK ® surrogate molecule, we observed comparable antitumor activity but achieved 5- to 10-fold higher dose levels in nonhuman primate safety studies for STRO-004.Therefore, we believe that STRO-004 has the potential for an improved clinical therapeutic index over existing standard of care.

Therefore, we believe that STRO-004 has the potential for an improved clinical therapeutic index over existing standard of care.

We believe these features present a unique opportunity for clinical development of STRO-004 to address unmet medical needs in cervical, lung and breast cancer patients.

We believe STRO-004 has been precisely designed and optimized to provide the potential for a best-in-class ADC targeting TF.

Our proprietary non-natural amino acid, which provides the substrate for conjugation to our proprietary β-glucuronidase cleavable exatecan linker warhead, have been placed at what we believe are the optimal sites in the amino acid sequence of our high affinity anti-TF antibody, resulting in enhanced performance and stability in preclinical in vitro and in vivo models.

Our proprietary non-natural amino acid, which provides the substrate for conjugation to our proprietary β-glucuronidase cleavable exatecan linker warhead, has been placed at what we believe are the optimal sites in the amino acid sequence of our high affinity anti-TF antibody, resulting in enhanced performance and stability in preclinical in vitro and in vivo models.

These models also suggest that our β-glucuronidase cleavable linkers may provide greater tumor specificity and enhanced tolerability relative to a protease-cleavable linker delivering an exatecan payload.

In particular, in a non-human primate safety study, we did not observe neutropenia, ocular toxicity signals or lung toxicity, or ILD, signals, even in the highest dose cohort for STRO-004.

In particular, in a nonhuman primate safety study, we did not observe neutropenia, ocular toxicity signals or ILD signals, even in the highest dose cohort for STRO-004.

Finally, our preclinical testing has shown that the exatecan payload delivered by STRO-004 elicits potent tumor cell killing, bystander activity and immunogenic cell death, which we believe may provide meaningful clinical benefit to patients.

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Its expression is correlated with poor prognosis in different cancers.

STRO-003, An ADC Directed Against ROR-1

In 2022, we nominated STRO-003 for further development and in 2024, we licensed the rights to develop and commercialize STRO-003 to Ipsen.

STRO-003 is a ROR1-targeting ADC for the treatment of ROR1-expressing solid tumors, including triple negative breast cancer, or TNBC, non-small cell lung cancer, or NSCLC, and ovarian cancer.

Currently, there are no therapeutics approved that specifically target ROR1, although there is one ROR1-targeting ADC, zilovertamab vedotin, or ZV, also known as MK-2140, or VLS-101, in Phase 2 testing targeting diffuse large B-cell lymphoma, or DLBCL, mantle cell lymphoma, or MCL, NSCLC, and breast cancer.

Based on preclinical in vitro and in vivo data, we believe that STRO-003 has the potential for an improved therapeutic index compared to ZV.

We believe these features present a unique opportunity for clinical development of STRO-003 to address unmet medical needs in hematological malignancies, ovarian cancer, TNBC and NSCLC.

We believe STRO-003 has been precisely designed and optimized to provide the potential for a best-in-class ADC targeting ROR-1.

Our proprietary non-natural amino acid, which provides the substrate for conjugation to our proprietary β-glucuronidase cleavable exatecan linker warhead, has been placed at what we believe are the optimal sites in the amino acid sequence of our high affinity anti-ROR1 antibody, resulting in enhanced performance and stability in preclinical in vitro and in vivo models.

In particular, in a nonhuman primate safety study, we did not observe neutropenia, ocular toxicity signals or lung toxicity signals even in the highest dose cohort for STRO-003.

Finally, our preclinical testing has shown that the exatecan payload delivered by STRO-003 elicits

potent tumor cell killing, bystander activity and immunogenic cell death, which we believe may provide meaningful clinical benefit to patients.

STRO-003 Business Opportunity

We believe ROR1 is a favorable target for an ADC due to its limited normal tissue expression, as well as its prevalence in solid tumors and B cell malignancies, including chronic lymphocytic leukemia, or CLL, DLBCL, MCL, TNBC, NSCLC, and ovarian cancer.

Its expression is correlated with poor prognosis in different cancers.

If STRO-003 is successfully developed and commercialized by Ipsen, we will receive development, regulatory and commercialization milestone payments and royalties based on net sales by Ipsen.

Additional Discovery Efforts

We are also actively researching to identify new ADCs to add to our pipeline.

We are also actively researching to identify new ADCs and ADC 2 s to add to our pipeline.

We have multiple ADC discovery programs ongoing using our XpressCF+ ® platform.

Our protein engineering and chemistry efforts are focused on maximizing therapeutic indices, and our technology allows us to rapidly test our therapeutic hypotheses in significantly more product candidates than conventional protein synthesis allows in order to identify the best molecule to advance to the clinic.

We have also expanded our ADC technology platform to include iADCs.

Our XpressCF+ ® platform has enabled a groundbreaking technology to engineer homogeneous, dually conjugated immunostimulant and cytotoxic warheads on a single ADC molecule.

We have also expanded our ADC technology platform to include iADCs and ADC 2 s.

For iADCs, our XpressCF+ ® platform has enabled a groundbreaking technology to engineer homogeneous, dually-conjugated immunostimulant and cytotoxic warheads on a single ADC molecule.

Our novel iADC design is intended to deliver two different drugs directly to the tumor, to not only kill tumor cells but also locally prime an immune response to the patient’s particular tumor cells.

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We believe such ADC 2 molecules have the potential to provide the next generation of highly potent cancer therapeutics with acceptable safety and tolerability.

Our bispecific antibody drug discovery programs are focused on bispecific ADCs.

We believe such compounds can provide improved specificity for tumors and could potentially spare healthy tissues expressing one, but not both, of the antigens targeted by the bispecific ADC.

Our technology allows us to rapidly incorporate non-natural amino acids in varying numbers and positions, to identify the best cytokine modification for pharmacological activity, pharmacokinetics, and safety.

Furthermore, our technology enables rapid preclinical development and transition to cGMP manufacturing, ensuring speed to clinic in a promising field.

Our drug discovery teams are exploring novel immuno-oncology therapies, including cytokine-based therapies.

Collaboration and License Agreements

Merck Collaboration

In July 2018, we entered into an Exclusive Patent License and Research Collaboration Agreement (the “2018 Merck Agreement”) with Merck to jointly develop up to three research programs focusing on cytokine derivatives for cancer and autoimmune disorders.

Under the 2018 Merck Agreement, we received from Merck a non-refundable, non-creditable, upfront payment of $60.0 million in August 2018 for access to our technology and the identification and preclinical research and development of two target programs, with an option for Merck to engage us to continue these activities for a third program upon the payment of an additional amount.

The option to expand activities to a third program expired in January 2021.

In December 2021, Merck did not extend the research term for the second research program of the collaboration and that research program reverted to us.

The first program of the collaboration is focused on MK-1484, a distinct cytokine derivative molecule for the treatment of cancer.

In July 2022, the first patient was dosed with MK-1484 in a Phase 1 study.

We are eligible to receive aggregate contingent payments of up to approximately $500 million for the target program selected by Merck, assuming the development and sale of the related therapeutic candidate and all possible indications identified under the collaboration.

If one or more products from the target program is developed for non-oncology or a single indication, we will be eligible for reduced aggregate milestone payments.

In addition, we are eligible to receive tiered royalties ranging from mid-single digit to low teen percentages on the worldwide sales of any commercial products that may result from the collaboration.

Merck may terminate the 2018 Merck Agreement at any time with 60 days’ prior written notice.

Either we or Merck has the right to terminate the 2018 Merck Agreement based on the other party’s uncured material breach or bankruptcy.

Astellas Agreement

In June 2022, we entered into a license and collaboration agreement with Astellas, or the Astellas Agreement, for the development of immunostimulatory antibody-drug conjugates for up to three biological targets, to be identified by Astellas.

We will conduct research and pre-clinical development of any compound (as designated by Astellas) in each of the three programs in accordance with the terms of a research plan between us and Astellas.

In June 2024, Astellas notified us that it would not be nominating a third target program.

This decision was based on Astellas' strategic portfolio considerations.

We will conduct research and preclinical development of any compound (as designated by Astellas) in each of the two programs in accordance with the terms of a research plan between us and Astellas.

Astellas will have an exclusive worldwide license to develop and commercialize any such designated compound, subject to our rights to participate in cost and profit sharing in the United States, as described below.

Pursuant to the Astellas Agreement, we received from Astellas a one-time, nonrefundable, non-creditable, upfront payment of $90.0 million during the year ended December 31, 2022.

We are also eligible to receive up to $422.5 million in development, regulatory and commercial milestones for each product candidate, and tiered royalties ranging from low double-digit to mid-teen percentages on worldwide sales of any commercial products that may result from the collaboration, subject to customary deductions under certain circumstances.

We are also eligible to receive up to $422.5 million in development, regulatory and commercial milestone payments for each product candidate, and tiered royalties ranging from low double-digit to mid-teen percentages on worldwide sales of any commercial products that may result from the collaboration, subject to customary deductions under certain circumstances.

We can also elect to convert any product candidate into a cost and profit-sharing arrangement, for the United States only.

In the event we make such election, we will share commercialization costs and profits relating to such product candidate equally with Astellas in the United States, and no royalties will be due from Astellas for net sales of such product candidates in the United States.

In the event we make such election, we will share

commercialization costs and profits relating to such product candidate equally with Astellas in the United States, and no royalties will be due from Astellas for net sales of such product candidates in the United States.

The Astellas Agreement contains customary provisions for termination, including by Astellas for convenience upon 30 days’ written notice and by either party for cause, including for material breach (subject to cure).

We have certain reversion rights as to product candidates in connection with certain termination events.

Ipsen Agreement

In March 2024, we entered into an Exclusive License Agreement with Ipsen, or the Ipsen License Agreement, pursuant to which we licensed to Ipsen, on an exclusive basis, the right to research, develop, manufacture and commercialize STRO-003.

In consideration for the rights and licenses granted to Ipsen in the Ipsen License Agreement, (i) Ipsen paid the Company an upfront license fee in the amount of $50.0 million in April 2024 and (ii) Ipsen Biopharmaceuticals, Inc.

(USA), or Ipsen USA, a fully-owned Affiliate of Ipsen, purchased 4,827,373 shares of the Company’s common stock for $25.0 million, at a price of approximately $5.18 per share, in accordance with the terms set forth in a certain investment agreement by and between the Company and Ipsen USA dated March 29, 2024 (the “Ipsen Investment Agreement”, and, together with the Ipsen License Agreement, the “Ipsen Agreements”).

Further, we are also eligible to receive up to an additional $447.0 million in developmental and regulatory milestone payments, assuming multiple indications, and up to $360.0 million in sales milestone payments, as well as tiered royalty payments ranging from low double-digit to mid-teen digit percentages of annual net sales of STRO-003, subject to certain adjustments specified in the Ipsen License Agreement.

The royalty payment obligations under the Ipsen License Agreement expire on a country-by-country basis no earlier than ten years following the first commercial sale of STRO-003 in the applicable country.

Ipsen may terminate the Ipsen License Agreement for convenience with sixty calendar days prior written notice or for certain other specified reasons.

In July 2024, we executed the Transition Services Agreement, or TSA, with Ipsen.

The TSA outlines the terms and conditions for transition services requested by Ipsen as part of the Ipsen License Agreement.

Further, as part of the transition activities under the TSA, we executed with Ipsen a Material Transfer Agreement, or MTA, to govern the transfer of certain materials to Ipsen for research and development purposes.

In December 2024, we executed the Manufacturing and Supply Agreement, or MSA, with Ipsen.

The MSA outlines the terms and conditions for certain manufacturing services, manufacturing transition activities and transfer of the manufacturing technology as part of the Ipsen License Agreement.

The pricing is based on an agreed upon cost-plus arrangement.

Vaxcyte (formerly known as SutroVax) Relationship

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Effective immediately upon agreement to the Form Definitive Agreement, we and Vaxcyte entered into Amendment No 3., or Amendment 3, to that certain license agreement between us and Vaxcyte, dated August 1, 2014, and amended and restated on October 12, 2015, and amended again on May 9, 2018 and May 29, 2018, or the License Agreement.

in lower royalties payable by Vaxcyte under certain circumstances, (ii) the ownership, prosecution, maintenance and enforcement of certain intellectual property rights licensed or arising under the License Agreement, and (iii) the timing and form for financial reporting of royalty payment calculations.

Amendment 3 amended certain terms of the License Agreement including with respect to (i) royalty reduction provisions applicable in the event of expiration of relevant patent claims, which would result in lower royalties payable by Vaxcyte under certain circumstances, (ii) the ownership, prosecution, maintenance and enforcement of certain intellectual property rights licensed or arising under the License Agreement, and (iii) the timing and form for financial reporting of royalty payment calculations.

In November 2023, or the Exercise Date, Vaxcyte exercised the Option by submitting written notice thereof to us and concurrently paid us $50.0 million in cash as the first of two installment payments for the Option exercise price.

Under the Vaxcyte Agreement, Vaxcyte is obligated to pay us an additional $25.0 million in cash within six months of the Exercise Date as the second of two installment payments for the Option exercise price.

In May 2024, Vaxcyte paid us an additional $25.0 million in cash as the second of two installment payments for the Option exercise price under the Vaxcyte Agreement.

Upon the occurrence of certain regulatory milestones, Vaxcyte would be obligated to pay us certain additional milestone payments totaling up to $60.0 million in cash.

In the event that Vaxcyte undergoes a change of control, certain rights and payments may be accelerated.

We hold 0.7 million shares of common stock of Vaxcyte and are eligible for four percent royalties on worldwide net sales of any vaccine candidates for human health use under the license agreement, except for royalties on sales of vaccines for prophylaxis of invasive pneumococcal disease, such as VAX-24 or VAX-31, which are owned by Blackstone, as discussed below.

We are eligible for four percent royalties on worldwide net sales of any vaccine candidates for human health use under the license agreement, except for royalties on sales of vaccines for prophylaxis of invasive pneumococcal disease, such as VAX-24 or VAX-31, which are owned by Blackstone, as discussed below.

Also, we retain the right to discover and develop vaccines for the treatment or prophylaxis of any disease that is not caused by an infectious pathogen, including cancer.

During 2024, we sold 0.7 million shares of Vaxcyte common stock for net proceeds of $74.0 million, and no longer hold any shares of Vaxcyte common stock.

Vaxcyte has the right to terminate the Vaxcyte license agreement for convenience upon prior written notice.

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In December 2021, we entered into the Tasly License Agreement with Tasly to grant an exclusive license to develop and commercialize STRO-002 in Greater China.

Tasly will pursue the clinical development, regulatory approval, and commercialization of STRO-002 in multiple indications, including ovarian cancer, non-small cell lung cancer, triple-negative breast cancer, and other indications in Greater China.

Tasly will pursue the clinical development, regulatory approval, and commercialization of STRO-002 in multiple indications, including ovarian cancer, NSCLC, TNBC, and other indications in Greater China.

We retained development and commercial rights of STRO-002 globally outside of Greater China, including the United States.

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In September 2023, we received a $5.0 million contingent payment from Tasly, net of withholding tax of $0.5 million, related to the first patient dosed in the REFRaME-O1 trial for luvelta.

The REFRaME-O1 study consists of two parts, Part I being the dose-finding portion and Part II being the portion of the study that will focus on the selected dose from Part I, and is intended to generate data to enable the potential registration of luvelta.

Although we currently intend to conduct the REFRaME-O1 study to completion, we have the sole discretion to terminate the REFRaME-O1 study at any time.

As such, we have agreed with Tasly that, in the event we terminate the REFRaME-O1 study prior to dosing the first patient in Part II, we will refund Tasly the contingent payment received by us within 30 days of such study termination.

In October 2023, we received a $5.0 million contingent payment from Tasly, net of withholding tax of $0.5 million, after Tasly received its first IND clearance by National Medical Products Administration, or NMPA, in Greater China.

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As such, we retain the revenue interest in royalties from Vaxcyte on sales of all products other than a PCV product, such as VAX-24 or VAX-31.

BMS Collaboration

In September 2014, we signed a Collaboration and License Agreement with BMS to discover and develop bispecific antibodies and/or ADCs, focused primarily on the field of immuno-oncology, using our proprietary integrated cell-free protein synthesis platform, XpressCF ® .

In August 2017, we entered into an amended and restated collaboration and license agreement with BMS to refocus the collaboration on four programs that were advancing through preclinical development, including an ADC program targeting B cell maturation antigen, or the BCMA ADC, CC-99712.

In May 2019, the U.S.

Food and Drug Administration cleared the IND application for the BCMA ADC, which was discovered and manufactured by us and is the first collaboration program IND.

In June 2023, we received a notice of termination from BMS indicating that it was terminating the BMS Agreement and stopping development of CC-99712 due to a portfolio prioritization decision.

The termination of the BMS Agreement was effective as of October 7, 2023, or the Termination Date.

Following the Termination Date, we have sole worldwide rights to CC-99712.

EMD Serono Collaboration

We signed a Collaboration Agreement and a License Agreement with EMD Serono in May 2014 and September 2014, respectively, which were entered into in contemplation of each other.

The Collaboration Agreement was subsumed into the License Agreement, or the MDA Agreement, which agreement is to develop ADCs for multiple cancer targets.

Our collaboration with EMD Serono has yielded a novel bispecific ADC product candidate targeting EGFR and MUC1, known as M1231, for which an IND submission was filed in the second half of 2020.

In March 2023, EMD Serono disclosed its decision to close the Phase 1a trial of M1231 in patients with solid tumors and not initiate a previously planned expansion study.

EMD Serono stated that the decision was based on strategic portfolio considerations.

BioNova Relationship

In October 2021, we entered into the BioNova Option Agreement to confer BioNova the right to obtain exclusive rights to develop and commercialize STRO-001 in Greater China and amended the BioNova Option Agreement with BioNova in the first quarter of 2023.

In March 2024, BioNova notified us that it had decided to terminate both the BioNova Option Agreement and clinical development of STRO-001 in Greater China.

Following receipt of this notice, we decided to suspend development of STRO-001.

Stanford License

In October 2007, we entered into an Amended and Restated Exclusive Agreement, or the Stanford License, with the Board of Trustees of the Leland Stanford Junior University (Stanford), that grants us an exclusive license, with the right to sublicense, under the patent rights owned by Stanford covering certain technology rights related to our XpressCF ® expression system.

We were required to make milestone payments to Stanford of approximately $930,000 on the accomplishment of certain development and regulatory milestones, which total amount has been paid as of December 31, 2021.

No additional milestone payments are due under the Stanford License.

Additionally, we owe Stanford annual license maintenance fees of $75,000, which may be creditable against earned royalties in such year and are required to reimburse Stanford for ongoing patent-related costs.

We owe Stanford annual license maintenance fees of $75,000, which may be creditable against earned royalties in such year and are required to reimburse Stanford for ongoing patent-related costs.

We are also required to pay to Stanford low single digit royalties on net sales and to share any sublicensing income received related to the licensed technology.

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Extract and Reagents

We manufacture our cell-free extract and related reagents in our GMP manufacturing facility in San Carlos, California for our clinical trials and supply commitments.

We have identified a contract manufacturing organization, or CMO, to serve as our strategic partner for the production of cell-free extract and have initiated technology transfer to this CMO.

We have historically manufactured our cell-free extract and related reagents in our GMP manufacturing facility in San Carlos, California for our clinical trials and supply commitments.

We have identified a contract manufacturing organization, or CMO, to serve as our strategic partner for the production of cell-free extract and

have initiated technology transfer to this CMO.

Similarly, we have identified a CMO to produce custom reagents used in our cell-free production and have initiated this technology transfer as well.

The technology transfer for production of custom reagents was substantially completed in 2023 and we expect the technology transfer for production of cell-free extract to be substantially completed in the first half of 2024.

The technology transfer for production of custom reagents was substantially completed in 2023 and the technology transfer for production of cell-free extract was substantially completed in 2024.

Given the success of these technology transfers, we are transitioning our extract and reagent manufacturing strategy to an outsourced model and plan to wind down our manufacturing activities in our San Carlos facility no later than the end of 2025.

Drug Substance and Drug Product

Our process development and manufacturing strategies are tailored to rapidly advance our product candidates, including the use of a supply chain of established CMOs to ensure successful execution.

The production of antibodies will be done by either us or CMOs, depending on our internal cGMP production capacity.

We have identified a CMO to produce the antibody component of our products at scale and technology transfer of the manufacturing process is underway.

The production of antibodies in 2025 will be done by either us or CMOs, depending on our internal cGMP production capacity.

We expect to transition these activities entirely to our CMO network by the end of 2025.

We have identified multiple CMOs with the ability to produce the antibody component of our products at different scales and we have successfully completed technology transfer of the manufacturing process to one or more of these CMOs.

The production of all other necessary elements for the manufacture of our ADC product candidates, and the final manufacture of the ADC drug product, will be handled entirely by CMOs.

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The clinical development pipeline for cancer includes small molecules, antibodies, vaccines, cell therapies and immunotherapies from a variety of companies and institutions.

We also face substantial competition from biotechnology and biopharmaceutical companies developing products with FolRα-targeted therapies, including naked antibodies, small molecule drug conjugates, ADCs, and T cell retargeting molecules.

The most advanced clinically active agent targeting FolRα to date has been ELAHERE ® (mirvetuximab soravtansine IMGN853), an ADC composed of a FolRα-binding antibody linked to the tubulin-disrupting maytansinoid, DM4, via a cleavable linker.

Other large pharmaceutical companies are developing a FolRα-targeted ADC for the treatment of cancers, including ovarian cancers.

We also face substantial competition from biotechnology and biopharmaceutical companies developing products with TF-targeted therapies.

The most advanced clinically active agent targeting TF to date has been TIVDAK ® (tisotumab vedotin-tftv;

TF-011-MMAE), an ADC currently approved for recurrent or metastatic cervical cancer that is composed of a TF-binding antibody linked to the tubulin-disrupting antimitotic agent, MMAE, via a cleavable linker.

Other pharmaceutical companies are developing TF-targeted ADCs for the treatment of a broad range of advanced or metastatic cancers, including the indications we may select for STRO-004 development.

Many of our competitors, either alone or with strategic partners, have substantially greater financial, technical, manufacturing, marketing, sales, supply and human resources or experience than we have.

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These patents and patent applications include claims relating to:

• bacterial strains, and extracts prepared therefrom, comprising an engineered Release Factor 1 protein, which facilitates incorporation of non-natural amino acids into proteins;

• bacterial strains, and extracts prepared therefrom, comprising combinations of chaperone proteins, which facilitate expression of complex eukaryotic proteins in bacterial extracts;

• bacterial strains having an oxidative cytoplasm;

• Release Factor 1-deficient E.

coli cells, and methods of expressing proteins therewith;

• cells encoding T7 RNA polymerase, and methods of producing thereof;

• spray-dried extracts for cell-free protein synthesis and methods of producing thereof;

• large scale production of antibody using pre-fabricated light chain;

• non-natural amino acid tRNA synthetases;

• antibodies with engineered CH2 domains;

• antibodies with site-specific glutamine tags;

• antibodies and antibody fragments containing one or more non-natural amino acids at defined positions in their amino acid sequences;

• antibodies targeting receptors of interest, including FolRα, BCMA, ROR1, Tissue Factor, CD3 and EpCAM, and methods of treating therewith;

• ADCs targeting receptors of interest, including FolRα, ROR1, Tissue Factor and BCMA, and methods of treating therewith;

• combination therapies with anti-Folα ADCs, and methods of treating therewith;

• iADCs, and TLR7, TLR7/8, and STING agonists, and methods of treating therewith;

• ADC 2 , and methods of treating therewith;

• an exatecan linker-warhead that is used in our STRO-003 and STRO-004 product candidates;

• hemiasterlin, both as a cytotoxin and as a linker-warhead, which is used in our STRO-002 product candidate;

• para-azidomethylphenylalanine, or pAMF, and proteins comprising pAMF, our workhorse non-natural amino acid which is primarily used when we conjugate molecules to proteins produced with our XpressCF+ ® platform.

Our issued patents, and any patents that may issue from our pending patent applications, in our solely owned patent portfolio are expected to expire between January 2030 and October 2044, absent any patent term adjustments or extensions.

Our patent portfolio includes the following families and/or groups of families:

• XpressCF ® Platform .

We have approximately 9 patent families related to our XpressCF ® platform, which include claims directed to certain bacterial strains and extracts prepared therefrom and methods of producing thereof, extract formulations and methods of making thereof, methods of producing antibodies using prefabricated light chain, and methods of producing high cell density fermentations and extracts prepared therewith.

Our issued patents, and any patents that may issue from our pending patent applications, related to our XpressCF ® platform are expected to remain in force until various times between October 2033 and December 2045, absent any patent term adjustments or extensions.

• XpressCF+ ® Platform and ADC Platform .

We have approximately 12 patent families related to our XpressCF+ ® platform and ADC platform, which include claims directed to para-azidomethylphenylalanine (pAMF) and proteins comprising pAMF, non-natural amino acid tRNA

synthetases, antibodies with engineered CH2 domains, antibodies with site-specific glutamine tags, antibodies and antibody fragments containing one or more non-natural amino acids at defined positions in their amino acid sequences, dual conjugates (including iADC and ADC 2 ), and high drug antibody ratio (DAR) conjugates and methods of treating therewith.

Our issued patents, and any patents that may issue from our pending patent applications, related to our XpressCF+ ® platform and ADC platform are expected to remain in force until various times between June 2033 and October 2045, absent any patent term adjustments or extensions.

We have approximately 2 patent families related to STRO-004, which include composition of matter and methods of treatment claims directed to our lead product candidate, STRO-004, and composition of matter, methods of treatment, and methods of making claims to exatecan linker-payloads and conjugates.

Any patents that issue from these patent applications will expire between June 2043 and October 2044, absent any patent term adjustments or extensions.

We have approximately 2 patent families related to STRO-003, which include composition of matter and methods of treatment claims directed to our lead product candidate, STRO-003, and composition of matter, methods of treatment, and methods of making claims to exatecan linker-payloads and conjugates.

Our issued patent, and any patents that may issue from our pending patent applications, related to our STRO-003 are expected to remain in force until 2043, absent any patent term adjustments or extensions.

In addition, we have exclusively licensed the following patent portfolio from Stanford:

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This patent portfolio includes claims relating to methods related to in vitro protein synthesis that we use in our XpressCF ® platform and XpressCF+ ® platform when discovering, developing and manufacturing our product candidates.

Remaining patents in our patent portfolio licensed from Stanford are expected to expire between July 2024 and January 2028, absent any patent term adjustments or extensions.

Remaining patents in our patent portfolio licensed from Stanford are expected to expire between March 2025 and January 2028, absent any patent term adjustments or extensions.

As for the XpressCF ® platform, XpressCF+ ® platform, product candidates and processes we develop and commercialize, in the normal course of business, we intend to pursue, where appropriate, patent protection or trade secret protection relating to compositions, methods of manufacture, assay methods, methods of use, treatment of indications, dosing and formulations.

We may also pursue patent protection with respect to product development processes and technology.

The following table describes the potentially material patents and patent applications owned or licensed by us.

Patent Relevance

Expiration or

(Absent patent

term extension

or adjustment)

Jurisdictions

XpressCF ® platform

Owned by Sutro

US, AU, CA, CN, EP, IL, IN, JP, KR, SG

XpressCF ® platform

Owned by Sutro

US, AU, CA, CN, EP, HK, IL, IN, JP, KR

XpressCF ® platform

Owned by Sutro

XpressCF ® platform

Owned by Sutro

XpressCF ® platform

Owned by Sutro

US, AU, BR, CA, CN, EP, IL, IN, JP, KR, SG, TW

XpressCF ® platform

Owned by Sutro

XpressCF ® platform

Owned by Sutro

US, AU, CN, EP, HK, IL, IN, JP, KR, SG

Owned by Sutro

US, AU, BR, CA, CN, EP, HK, IL, IN, JP, KR, SG

Owned by Sutro

US, AU, BR, CA, CN, EP, HK, IL, IN, JP, KR, MX, NZ, SG, ZA

Owned by Sutro

US, CA, EP, HK, KR

US, AU, BR, CN, EP, IL, IN, JP, SG

Owned by Sutro

US, EP, HK, JP

Owned by Sutro

Co-owned by Sutro

Owned by Sutro

STRO-003 and STRO-004

Owned by Sutro

We continually assess and refine our intellectual property strategy as we develop new platform technologies and product candidates.

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For this and more comprehensive risks related to our proprietary technology, inventions, improvements, platforms, and product candidates, please see the section entitled “Risk Factors—Risks Related to Intellectual Property.”

We intend to file applications for trademark registrations in connection with our product candidates in various jurisdictions, including the United States.

We have filed for trademark protection of the Sutro Biopharma marks, the XpressCF ® mark and the XpressCF+ ® mark with the USPTO.

Additionally, we filed for trademark protection of the XpressPDF ® mark, XpressRNAP ® mark, XpressRS ® mark, XpresstRNA ® mark and XtractCF ® mark with the USPTO.

We also filed for trademark protection of the clinical trial marks.

XpressCF ® refers to our cell-free protein synthesis technology as a whole, and XpressCF+ ® refers specifically to cell-free protein synthesis incorporating one or more non-natural amino acids.

The Sutro Biopharma marks were registered by the USPTO in 2014 and 2018, the XpressCF ® mark was registered by the USPTO in 2017, and XpressCF+ ® mark was registered by the USPTO in 2017.

The XpressRNAP ® mark, the XpressRS ® mark, and the XpresstRNA ® mark were registered in the USPTO in 2021.

The XpressPDF ® mark and the XtractCF ® mark were registered in the USPTO in 2022.

We also rely on trade secret protection for our confidential and proprietary information.

Although we take steps to protect our confidential and proprietary information as trade secrets, including through contractual means with our employees and consultants, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or disclose our technology.

In addition to patent protection, we also rely on trademark registration, trade secrets, know how, other proprietary information and continuing technological innovation to develop and maintain our competitive position.

We seek to protect and maintain the confidentiality of proprietary information to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

Although we take steps to

protect our confidential and proprietary information as trade secrets, including through contractual means with our employees, consultants, partners, and contractors, third parties may independently develop substantially equivalent proprietary information and techniques or otherwise gain access to our trade secrets or disclose our technology.

Thus, we may not be able to meaningfully protect our trade secrets.

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We conduct regular audits of our information security systems, including our on-site and cloud-based information systems and strive to continuously improve the robustness of our security and information recovery systems in the event of, for example, a cyberattack or natural disaster that compromises our data integrity.

As part of our security framework, we review publicly available cybersecurity assessments of our third-party partners and vendors to evaluate potential risks.

In addition, we conduct regular training and testing of our employees to identify, and report cyberattacks, including phishing and other forms of social engineering.

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Failure to comply with applicable U.S.

requirements may subject a company to a variety of administrative or judicial sanctions, such as clinical hold, FDA refusal to approve pending BLAs, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, civil penalties, and criminal prosecution.

may subject a company to a variety of administrative or judicial sanctions, such as clinical hold, FDA refusal to approve pending BLAs, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, civil penalties, and criminal prosecution.

Biological product development for a new product or certain changes to an approved product in the United States typically involves preclinical laboratory and animal tests, the submission to the FDA of an IND, which must become effective before clinical testing may commence, and adequate and well-controlled clinical trials to establish the safety and effectiveness of the biologic for each indication for which FDA approval is sought.

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A 30-day waiting period after the submission of each IND is required prior to the commencement of clinical testing in humans.

If the FDA has neither commented on nor questioned the IND within this 30-day period, the clinical trial proposed in the IND may begin.

If the FDA has neither commented on nor questioned the IND and placed the IND on clinical hold within this 30-day period, the clinical trial proposed in the IND may begin.

Clinical trials involve the administration of the investigational biologic to healthy volunteers or patients under the supervision of a qualified investigator.

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In most cases, the FDA requires two adequate and well-controlled Phase 3 clinical trials to demonstrate the efficacy of the biologic.

A single Phase 3 trial with other confirmatory evidence may be sufficient in certain oncological conditions where the trial is a large multicenter trial demonstrating internal consistency and a statistically very persuasive finding of a clinically meaningful effect on mortality, irreversible morbidity or prevention of a disease with a potentially serious outcome and confirmation of the result in a second trial would be practically or ethically impossible.

A single Phase 3 trial may be sufficient in certain oncological conditions, including (i) where the trial is a large multicenter trial demonstrating internal consistency and a statistically very persuasive finding of a clinically meaningful effect on mortality, irreversible morbidity or prevention of a disease with a potentially serious outcome and confirmation of the result in a second trial would be practically or ethically impossible or (ii) when in conjunction with confirmatory evidence.

The manufacturer of an investigational drug in a Phase 2 or 3 clinical trial for a serious or life-threatening disease is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for expanded access.

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The FDA has 60 days from its receipt of a BLA to determine whether the application will be filed based on the agency’s threshold determination that it is sufficiently complete to permit substantive review.

The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission and may request additional information.

In that event, the BLA must be resubmitted with the additional information.

The resubmitted application also is subject to review before the FDA files it.

Once the submission is filed, the FDA begins an in-depth review.

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In addition to other benefits, such as the ability to engage in more frequent interactions with the FDA, the FDA may initiate review of sections of a fast track product’s BLA before the application is complete.

This rolling review is available if the applicant provides, and the FDA approves, a schedule for the submission of the remaining information and the applicant pays applicable user fees.

This rolling review is available if the applicant provides, and the FDA approves, a schedule for the submission of the remaining information, the FDA determines after preliminary evaluation of clinical data submitted by the sponsor that the product may be effective, and the applicant pays applicable user fees.

However, the FDA’s time period goal for reviewing an application does not begin until the last section of the BLA is submitted.

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Failure to conduct required post-approval trials, or confirm a clinical benefit during post-marketing trials, will allow the FDA to withdraw the biologic from the market on an expedited basis.

All promotional materials for biologic candidates approved under accelerated

regulations are subject to prior review by the FDA.

The Food and Drug Omnibus Reform Act, or FDORA, was recently enacted, which included provisions related to the accelerated approval pathway.

All promotional materials for biologic candidates approved under accelerated regulations are subject to prior review by the FDA.

The Food and Drug Omnibus Reform Act, or FDORA, included provisions related to the accelerated approval pathway.

Pursuant to FDORA, the FDA is authorized to require a post-approval study to be underway prior to approval or within a specified time period following approval.

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Orphan Drug Designation

Under the Orphan Drug Act, the FDA may grant orphan drug designation to biological products intended to treat a rare disease or condition—generally a disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States, there is no reasonable expectation that the cost of developing and making a product available in the United States for such disease or condition will be recovered from sales of the product.

Under the Orphan Drug Act, the FDA may grant orphan drug designation to biological products intended to treat a rare disease or condition—generally a disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States and there is no reasonable expectation that the cost of developing and making a product available in the United States for such disease or condition will be recovered from sales of the product.

Orphan drug designation must be requested before submitting a BLA.

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A product is clinically superior if it is safer, more effective or makes a major contribution to patient care.

In the case of a biological product, the same drug is a drug that contains the same principal molecular features.

In the case of a biological product, the same drug is a drug that contains the same principal molecular structural features.

Orphan drug exclusivity does not prevent the FDA from approving a different drug or biological product for the same disease or condition, or the same biological product for a different disease or condition.

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The Best Pharmaceuticals for Children Act, or BPCA, provides a six-month extension of any non-patent exclusivity for a biologic if certain conditions are met.

Conditions for exclusivity include the FDA’s determination that information relating to the use of a new biologic in the pediatric population may produce health benefits in that population, FDA making a written request for pediatric studies, and the applicant agreeing to perform, and

reporting on, the requested studies within the statutory timeframe.

Applications under the BPCA are treated as priority applications, with all of the benefits that designation confers.

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This includes claims made to programs where the federal government reimburses, such as Medicaid, as well as programs where the federal government is a direct purchaser, such as when it purchases off the Federal Supply Schedule.

pharmaceutical and other healthcare companies have been prosecuted under these laws for allegedly inflating drug prices they report to pricing services, which in turn were used by the government to set Medicare and Medicaid reimbursement rates, and for allegedly providing free product to customers with the expectation that the customers would bill federal programs for the product.

Several pharmaceutical and other healthcare companies have been prosecuted under these laws for allegedly inflating drug prices they report to pricing services, which in turn were used by the government to set Medicare and Medicaid reimbursement rates, and for allegedly providing free product to customers with the expectation that the customers would bill federal programs for the product.

In addition, certain marketing practices, including off-label promotion, may also violate false claims laws.

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In addition, HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009, or HITECH, imposes obligations on certain healthcare providers, health plans, and healthcare clearinghouses, known as covered entities, as well as their business associates that perform certain services involving the storage, use or disclosure of individually identifiable health information, including mandatory contractual terms, with respect to safeguarding the privacy, security, and transmission of individually identifiable health information, and require notification to affected individuals and regulatory authorities of certain breaches of security of individually identifiable health information.

In addition, many state laws govern the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may not have the same effect, and often are not preempted by HIPAA.

In addition, many state laws govern the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may

not have the same effect, and often are not preempted by HIPAA.

For example, the California Consumer Privacy Act (“CCPA”), which went into effect on January 1, 2020, creates new data privacy obligations for covered companies and provides new privacy rights to California residents.

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Interim reimbursement levels, if applicable, may also be insufficient to cover a pharmaceutical company’s costs and may not be made permanent.

Moreover, eligibility for reimbursement does not imply that any pharmaceutical product will be reimbursed in all cases or at a rate that covers a pharmaceutical

company’s costs, including research, development, manufacture, sale and distribution.

Moreover, eligibility for reimbursement does not imply that any pharmaceutical product will be reimbursed in all cases or at a rate that covers a pharmaceutical company’s costs, including research, development, manufacture, sale and distribution.

In addition, coverage policies and third-party reimbursement rates may change at any time.

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government rebate programs and additional downward pressure on pharmaceutical product prices.

Several healthcare reform proposals recently culminated in the enactment of Inflation Reduction Act, or IRA, which among other things, allows the Department of Health and Human Services, or HHS, to directly negotiate the selling price of a statutorily specified number of drugs and biologics each year that CMS reimburses under Medicare Part B and Part D.

Several healthcare reform proposals culminated in the enactment of Inflation Reduction Act, or IRA, which among other things, allows the Department of Health and Human Services, or HHS, to directly negotiate the selling price of a statutorily specified number of drugs and biologics each year that CMS reimburses under Medicare Part B and Part D.

The negotiated price may not exceed a statutory ceiling price.

Only high-expenditure single-source biologics that have been approved for at least 11 years (7 years for drugs) can be selected by CMS for negotiation, with the negotiated price taking effect two years after the selection year.

Negotiations for Medicare Part D products take place in 2024 with the negotiated price taking effect in 2026, and negotiations for Medicare Part B products will begin in 2026 with the negotiated price taking effect in 2028.

In August 2023, HHS announced the ten Medicare Part D drugs and biologics that it selected for negotiations.

HHS will announce the negotiated maximum fair prices by September 1, 2024, and this price cap, which cannot exceed a statutory ceiling price, will go into effect on January 1, 2026.

A drug or biological product that has an orphan drug designation for only one rare disease or condition will be excluded from the IRA’s price negotiation requirements, but will lose that exclusion if it receives designations for more than one rare disease or condition, or if is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation.

The IRA also impose rebates on Medicare Part D and Part B drugs whose prices have increased at a rate greater than the rate of inflation.

For 2026, the first year in which negotiated prices become effective, CMS selected 10 high-cost Medicare Part D products in 2024, and the negotiated maximum fair price for each product has been announced.

CMS has selected 15 additional Medicare Part D drugs for negotiated maximum fair pricing in 2027.

For 2028, an additional 15 drugs, which may be covered under either Medicare Part B or Part D, will be selected, and for 2029 and subsequent years, 20 Part B or Part D drugs will be selected.

A drug or biological product that has an orphan drug designation for only one rare disease or condition will be excluded from the IRA’s price negotiation requirements, but will lose that exclusion if it receives designations for more than one rare disease or condition, or if it is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation.

The IRA also impose rebates on Medicare Part D and Part B drugs whose prices have increased at a rate greater than the rate of inflation, and in November 2024, CMS finalized regulations for the Medicare Part B and Part D inflation rebates.

The IRA also extends enhanced subsidies for individuals purchasing health insurance coverage in ACA marketplaces through plan year 2025.

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Thus, while it is unclear how the IRA will be implemented, it will likely have a significant impact on the biopharmaceutical industry and the pricing of prescription drug products.

We expect additional statutory, regulatory, and administrative healthcare reform initiatives to be enacted and implemented in the future.

At the state level, legislatures have increasingly passed legislation and implemented regulations designed to control pharmaceutical product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access, and marketing cost disclosure and transparency measures, and in some cases, designed to encourage importation from other countries and bulk purchasing.

Human Capital Resources

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None of our employees are represented by a labor union or covered by collective bargaining agreements, and we believe our relationship with our employees is good.

However, in March 2025, we executed a significant reduction in workforce, which may negatively impact our relationship with our employees going forward.

We recognize that attracting, motivating, and retaining talent at all levels is vital to continuing our success.

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We embarked upon a Company-wide leadership development program which offered the opportunity for every employee to continue to build upon their learning.

For our talent pipeline assessment and development, we work closely with individual scientific and business functional leaders to identify our high-performing and high-potential employees, by conducting a company-wide talent assessment

and calibration.

This assessment is completed annually to ensure we tie together our incentives, development, and recognition to retain and attract the people we need to drive our success.

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To this end, we have prepared a formal written succession plan for our senior executives and to provide guidance for the next generation of our leaders to ensure an orderly and smooth transition in the event of an executive departure.

While senior management is primarily responsible for developing our succession plan, our Nominating and Corporate Governance Committee of our Board of Directors (with respect to the CEO) and Compensation Committee of our Board of Directors (with respect to other executives) oversee and guide our process and thinking.

While senior management is primarily responsible for developing our succession plan, our Nominating and Corporate

Governance Committee of our Board of Directors (with respect to the CEO) and Compensation Committee of our Board of Directors (with respect to other executives) oversee and guide our process and thinking.

Corporate Information

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Risks Related to Our Business

We are a clinical stage biopharmaceutical company with no products approved for commercial sale.

We are an early stage biopharmaceutical company with no products approved for commercial sale.

We have a history of significant losses, expect to continue to incur significant losses for the foreseeable future and may never achieve or maintain profitability, which could result in a decline in the market value of our common stock.

We are a clinical stage biopharmaceutical company.

We are an early stage biopharmaceutical company.

Biotechnology product development is a highly speculative undertaking and involves a substantial degree of risk.

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Furthermore, we do not expect to generate any revenue from commercial product sales for the foreseeable future, and we expect to continue to incur significant operating losses for the foreseeable future due to the cost of research and development, preclinical studies and clinical trials and the regulatory approval process for our product candidates and manufacturing clinical and early commercial supply of our product candidates.

We expect our net losses to increase substantially as we progress further into clinical development of our lead programs and create additional infrastructure to support operations as a public company.

We expect our net losses to increase substantially as we progress further into development of our lead programs and create additional infrastructure to support operations as a public company.

However, the amount of our future losses is uncertain.

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In addition, we expect to continue to incur additional costs associated with operating as a public company.

Since our inception, we have invested a significant portion of our efforts and financial resources in research and development activities for our clinical-stage product candidates and the development of our technology platform, including our in-house manufacturing capabilities.

Clinical trials for our product candidates have required substantial funds to date and will continue to require substantial funds to complete.

Since our inception, we have invested a significant portion of our efforts and financial resources in research and development activities for our preclinical and clinical-stage product candidates and the development of our technology platform, including our in-house manufacturing capabilities.

Preclinical studies and clinical trials for our product candidates have required substantial funds to date and will continue to require substantial funds to complete.

As of December 31, 2024, we had $316.9 million in cash, cash equivalents and marketable securities.

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• our efforts to enhance operational systems and hire and retain key personnel, including personnel to support development of our product candidates and satisfy our obligations as a public company;

• general economic, industry and market conditions, including market volatility, high levels of inflation, changes in interest rates, uncertainty with respect to the federal debt ceiling and budget and potential government shutdowns related thereto.

• general economic, industry and market conditions, including market volatility, high levels of inflation, changes in interest rates, changes in tariffs and trade restrictions, uncertainty with respect to the federal debt ceiling and budget and potential government shutdowns related thereto.

If we are unable to obtain funding on a timely basis or on acceptable terms, we may have to delay, reduce or terminate our research and development programs and preclinical studies or clinical trials, limit strategic opportunities or undergo reductions in our workforce or other corporate restructuring activities.

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If we or our collaborators are unable to complete development of or commercialize our product candidates or experience significant delays in doing so, our business will be materially harmed.

We have no products on the market and all of our product candidates for cancer therapy are in clinical development.

Our most advanced product candidate, luvelta, is being evaluated in REFRαME-O1, a Phase 2/3 pivotal trial for treatment of women with platinum resistant ovarian cancer, as well as in additional clinical studies underway, including for treatment of women with endometrial cancer and children with pediatric AML.

We have no products on the market and all of our internal product candidates for cancer therapy are in preclinical development, including our most advanced candidate, STRO-004.

Additionally, we have programs that are being evaluated by partners in clinical trials and by us in earlier stages of discovery and preclinical development and may never advance to clinical-stage development.

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We have limited experience in conducting and managing the clinical trials necessary to obtain regulatory approvals, including approval by the FDA.

Before obtaining regulatory approval for the commercial distribution of our product candidates, we or an existing or future collaborator must

conduct extensive preclinical tests and clinical trials to demonstrate the safety and efficacy in humans of our product candidates.

Before obtaining regulatory approval for the commercial distribution of our product candidates, we or an existing or future collaborator must conduct extensive preclinical tests and clinical trials to demonstrate the safety and efficacy in humans of our product candidates.

We may not have the financial resources to continue development of, or to modify existing or enter into new collaborations for, a product candidate if we experience any issues that delay or prevent regulatory approval of, or our ability to commercialize, product candidates, including:

• negative or inconclusive results from our clinical trials or the clinical trials of others for product candidates similar to ours, leading to a decision or requirement to conduct additional preclinical testing or clinical trials or abandon a program;

• negative or inconclusive results from our, or our licensees’ clinical trials, or the clinical trials of others for product candidates similar to ours, leading to a decision or requirement to conduct additional preclinical testing or clinical trials or abandon a program;

• product-related side effects experienced by patients in our clinical trials or by individuals using drugs or therapeutic biologics similar to our product candidates;

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• occurrence of epidemics, pandemics or contagious diseases and potential effects on our business, clinical trial sites, highly complex supply chain and manufacturing facilities;

• greater than anticipated costs of our clinical programs;

• greater than anticipated costs of our preclinical studies and clinical programs;

• harmful side effects or inability of our product candidates to meet efficacy endpoints during clinical trials, which can be unpredictable even in light of earlier non-clinical and clinical data;

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We or our collaborators’ inability to complete development of or commercialize our product candidates or significant delays in doing so due to one or more of these factors, could have a material and adverse effect on our business, financial condition, results of operations and prospects.

Our business is dependent on the success of our product candidates, including luvelta, which is generated from our proprietary XpressCF ® and XpressCF+ ® platforms.

Our business is dependent on the success of our product candidates, including STRO-004, which are generated from our proprietary XpressCF ® and XpressCF+ ® platforms.

Existing and future preclinical studies and clinical trials of our product candidates may not be successful.

If we are unable to commercialize our product candidates or experience significant delays in doing so, our business will be materially harmed.

We have invested a significant portion of our efforts and financial resources in the development of our proprietary XpressCF ® and XpressCF+ ® platforms and our proprietary product candidates, luvelta, STRO-003 and STRO-004.

Our ability to generate commercial product revenues, which we do not expect will occur for many years, if ever, will depend heavily on the successful development and eventual commercialization of our product candidates.

We have not previously submitted a new drug application, or NDA, or a biologics license application, or BLA, to the FDA, or similar regulatory approval filings to comparable foreign authorities, for any product candidate, and we cannot be certain that our product candidates will be successful in clinical trials or receive regulatory approval.

In addition, although we believe that our REFRαME-O1 Phase 2/3 pivotal trial of luvelta for the treatment of women with platinum resistant ovarian cancer will provide a sufficient dataset to support submission of a BLA to the FDA or equivalent to regulatory agencies, we cannot assure you that the FDA will agree with our conclusions or require data prior to approval.

Further, our product candidates may not receive regulatory approval even if they are successful in clinical trials.

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Other countries also have their own regulations governing, among other things, clinical trials and commercial sales, as well as pricing and distribution of our product candidates, and we may be required to expend significant resources to obtain regulatory approval and to comply with ongoing regulations in these jurisdictions.

The success of luvelta, STRO-003 and STRO-004 and our other future product candidates will depend on many factors, including the following:

The success of STRO-004 and our other future proprietary product candidates will depend on many factors, including the following:

• successful enrollment of patients in, and the completion of, our clinical trials;

• receiving required regulatory approvals for the development and commercialization of our product candidates;

• receiving required regulatory approvals for the development, manufacturing, and commercialization of our product candidates;

• establishing our commercial manufacturing capabilities or making arrangements with third-party manufacturers;

• establishing successful technology transfers and collaborations to develop our product candidates with licensees, including our licensees with rights to luvelta in Greater China;

• establishing successful technology transfers and collaborations to develop our product candidates with potential licensees,

• obtaining and maintaining patent, trademark and trade secret protection and non-patent exclusivity for our product candidates and their components;

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Additionally, we have in the past and may in the future create benchmark molecules for comparative purposes.

For example, we have created a benchmark FolRα targeting antibody-drug conjugate, or ADC, using conventional technology that results in a heterogeneous ADC mixture.

We have compared luvelta to this benchmark molecule in multiple preclinical models.

We believe the results of these tests help us understand how the therapeutic index of luvelta compares to competitors’ product candidates.

For example, we have created a benchmark FRα targeting antibody-drug conjugate, or ADC, using conventional technology that results in a heterogeneous ADC mixture.

However, we cannot be certain that any benchmark molecule that we create is the same as the molecule we are attempting to recreate, and the results of the tests comparing any such benchmark molecule to any other potential or current product candidate may be different than the actual results of a head-to-head test of any such other potential or current product candidate against a competitor molecule.

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The actual timing of these milestones can vary dramatically compared to our estimates, in some cases for reasons beyond our control, such as health epidemics and pandemics, global instability and geopolitical conflicts within regions where our clinical trials are conducted.

For example, we intend to open a clinical trial site in Israel, which may face enrollment, operational or other difficulties due to conflicts within the region, including, for example, difficulties importing clinical study drug through Israeli customs, difficulties with patient enrollment, or difficulties with patients

or medical personnel accessing appropriate medical facilities.

For example, we may open clinical trial sites in jurisdictions that may face enrollment, operational or other difficulties due to conflicts within the region.

In addition, we rely on third party vendors, contractors and consultants to provide services in connection with our clinical trials.

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Further, the scientific evidence to support the feasibility of developing therapeutic treatments based on our XpressCF ® and XpressCF+ ® platforms is both preliminary and limited.

To date, our clinical stage product candidates have been tested in a limited number of clinical trial patients.

Our current and prior product candidates have been tested in a relatively limited number of clinical trial patients.

We may ultimately discover that our XpressCF ® and XpressCF+ ® platforms and any product candidates resulting therefrom do not possess certain properties required for therapeutic effectiveness.

XpressCF ® product candidates may also be unable to remain stable in the human body for the period of time required for the drug to reach the target tissue or they may trigger immune responses that inhibit the ability of the product candidate to reach the target tissue or that cause adverse side effects in humans.

XpressCF ® and XpressCF+ ® product candidates may also be unable to remain stable in the human body for the period of time required for the drug to reach the target tissue or they may trigger immune responses that inhibit the ability of the product candidate to reach the target tissue or that cause adverse side effects in humans.

We currently have only limited data, and no conclusive evidence, to suggest that we can introduce these necessary properties into these product candidates derived from our XpressCF ® and XpressCF+ ® platforms.

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Although our XpressCF ® and XpressCF+ ® platforms and certain product candidates have produced successful results in animal studies, they may not demonstrate the same chemical and pharmacological properties in humans and may interact with human biological systems in unforeseen, ineffective or harmful ways.

Further, in our oncology clinical trials to date, we have used achievement of stable disease as evidence for disease control (stable disease, partial response or complete response) by our product candidates;

however, the FDA does not view stable disease as an objective response for the purposes of FDA approval.

Results of our clinical trials could reveal a high and unacceptable severity and prevalence of side effects or unexpected characteristics.

Undesirable side effects could result in the delay, suspension or termination of clinical trials by us or regulatory authorities for a number of reasons.

In our clinical trials to date, our product candidates have been generally well tolerated, and the most common treatment-emergent adverse events, or TEAEs, that resulted in a treatment delay or dose reduction was reversible neutropenia.

We have also observed arthralgia as a TEAE.

It is possible that, as we test our product candidates in larger, longer and more extensive clinical trials or as the use of our product candidates becomes more widespread following any regulatory approval, illnesses, injuries, discomforts and other adverse events that were observed in earlier trials, as well as conditions that did not occur or went undetected in previous trials, will be reported by patients.

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We believe the FDA has limited experience with therapeutics in oncology or other disease areas developed in cell-free-based synthesis systems, which may increase the complexity, uncertainty and length of the regulatory approval process for our product candidates.

For example, our XpressCF ® ADC product candidates contain cleavable or non-cleavable linker-warhead

combinations or novel warheads that may result in unforeseen events when administered in a human.

For example, our ADC product candidates contain cleavable or non-cleavable linker-warhead combinations or novel warheads that may result in unforeseen events when administered in a human.

We and our existing or future collaborators may never receive approval to market and commercialize any product candidate.

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We or an existing or future collaborator may be required to perform additional or unanticipated clinical trials to obtain approval or be subject to post-marketing testing requirements to maintain regulatory approval.

If the products resulting from our XpressCF ® platform prove to be ineffective, unsafe or commercially unviable, our entire platform and pipeline would have little, if any, value, which would have a material and adverse effect on our business, financial condition, results of operations and prospects.

If the products resulting from our XpressCF ® and XpressCF+ ® platform prove to be ineffective, unsafe or commercially unviable, our entire platform and pipeline

would have little, if any, value, which would have a material and adverse effect on our business, financial condition, results of operations and prospects.

Results of preclinical studies and early clinical trials may not be predictive of results of future clinical trials.

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In some instances, there can be significant variability in safety or efficacy results between different clinical trials of the same product candidate due to numerous factors, including changes in trial procedures set forth in protocols, differences in the size and type of the patient populations, changes in and adherence to the dosing regimen and other clinical trial protocols and the rate of dropout among clinical trial patients.

In addition, results from compassionate use of our product candidates, such as luvelta to treat pediatric CFB/GLIS AML, may not be confirmed in Company-sponsored trials and/or may negatively impact the prospects for marketing approval for our product candidates.

however, the FDA does not view stable disease as an objective response for the purposes of FDA approval.

If we fail to receive positive results in clinical trials of our product candidates, the development timeline and regulatory approval and commercialization prospects for our most advanced product candidates, and, correspondingly, our business and financial prospects would be negatively impacted.

Interim, top-line, or preliminary data from our clinical trials that we announce may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we have publicly disclosed, and in the future will disclose, preliminary or top-line data from our preclinical studies and clinical trials, which are based on preliminary analyses of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review of the data related to the particular study or trial.

From time to time, we have publicly disclosed, and in the future will disclose, interim, top-line, or preliminary data from our preclinical studies and clinical trials, which are based on preliminary analyses of then-available data, and the results and related findings and conclusions are subject to change following a more comprehensive review and/or maturation of the data related to the particular study or trial.

We also make assumptions, estimations, calculations, and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data.

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If the final results differ from the interim, top-line, or preliminary data, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and to commercialize, our product candidates may be harmed, which may negatively affect our business, financial condition, results of operations, and prospects.

Moreover, from time to time, we have publicly disclosed, and in the future may disclose, interim data from our preclinical studies and clinical trials.

Interim data from clinical trials that we may complete are subject to the risk that one or more of the outcomes may materially change as patient enrollment continues and more data become available.

Adverse differences between top-line, preliminary, or interim data, on the one hand, and final data, on the other, could significantly harm our business prospects.

Further, disclosure of interim data by us or by our competitors could result in volatility in the price of our common stock.

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Additionally, the product candidates that we are developing are based on our proprietary XpressCF ® and XpressCF+ ® platforms, which are new technologies.

Market participants with significant influence over acceptance of new treatments, such as physicians and third-party payors, may not adopt an ADC product, or a product or treatment based on our novel cell-free production technologies, and we may not be able to convince the medical community and third-party payors to accept and use, or to provide favorable reimbursement for, any product candidates developed by us or our existing or future collaborators.

Market participants with significant influence over acceptance of new treatments, such as physicians and third-party payors, may not adopt an ADC product, or a product or treatment based on our novel cell-free production technologies, and the medical community and third-party payors may not be compelled to accept and use, or to provide favorable reimbursement for, any product candidates developed by us or our existing or future collaborators.

Market acceptance of our product candidates will depend on the following, among other factors:

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• the availability of coverage and adequate reimbursement from government and third-party payors;

• the availability of a commercially approved companion diagnostic or assay or biomarker to appropriately identify patients that will benefit from treatment;

• the pricing of our products, particularly as compared to alternative treatments;

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Because our product candidates are based on new technology, we expect that they will require extensive research and development and have substantial manufacturing and processing costs.

In addition, our estimates regarding potential market size for any indication may be materially different from what we discover to exist at the time we commence commercialization, if any, for a product, which could result in significant changes in our business plan and have a material adverse effect on our business, financial condition, results of operations and

Moreover, if any product candidate we commercialize fails to achieve market acceptance, it could have a material and adverse effect on our business, financial condition, results of operations, and prospects.

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Some of our future success depends on the successful development of this technology and products based on it.

To our knowledge, no regulatory authority has granted approval to any person or entity, including us, to market and commercialize therapeutics using our novel and unprecedented iADC or ADC 2 technology.

To our knowledge, no regulatory authority has granted approval to any person or entity, including us, to market and

commercialize therapeutics using our novel and unprecedented iADC or ADC 2 technology.

We may never receive approval to market and commercialize any potential iADC or ADC 2 product candidate.

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Since 2014, we have entered into several collaborations to develop and commercialize certain cancer and other therapeutics.

Our XpressCF ® and XpressCF+ ® platforms have also supported a spin-out company, Vaxcyte Inc., focused on discovery and development of vaccines for the treatment and prophylaxis of infectious disease.

Our XpressCF ® and XpressCF+ ® platforms have also supported a spin-out company, now known as Vaxcyte Inc., focused on discovery and development of vaccines for the treatment and prophylaxis of infectious disease.

In addition, we may in the future seek third-party collaborators for research, development and commercialization of other therapeutic technologies or product candidates.

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Any failure to successfully develop or commercialize our product candidates pursuant to our current or any future collaboration agreements could have a material and adverse effect on our business, financial condition, results of operations, and prospects.

Our existing collaborations with Astellas, Merck, Vaxcyte and Tasly are important to our business.

Our existing collaborations with Astellas, Ipsen, Vaxcyte and Tasly are important to our business.

If our collaborators cease development efforts under our existing or future collaboration agreements, fail to fulfill their contract obligations, or if any of those agreements are terminated, these collaborations may fail to lead to commercial products and we may never receive milestone payments or future royalties under these agreements.

We have entered into collaborations with other biotechnology companies to develop or commercialize several of our product candidates, and such collaborations currently represent a significant portion of our product pipeline and discovery and preclinical programs.

A substantial portion of our revenue to date has been derived from our collaborations, and a significant portion of our future revenue and cash resources is expected to be derived from some of these agreements, our royalty monetization agreement, or the Purchase Agreement, with an affiliate of Blackstone Life Sciences, or Blackstone, or other similar agreements into which we may enter in the future.

A substantial portion of our revenue to date has been derived from our collaborations, and a significant portion of our future revenue and cash resources is expected to be derived from some of these agreements, our royalty monetization agreement, or Purchase Agreement, with an affiliate of Blackstone Life Sciences, or Blackstone, or other similar agreements into which we may enter in the future.

Revenue from research and development collaborations depends upon continuation of the collaborations, payments for research and development and other services and product supply, and the achievement of milestones, contingent payments and royalties, if any, derived from future products developed from our research.

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As a result, our collaborators may elect to de-prioritize our programs, change their strategic focus or pursue alternative technologies in a manner that results in reduced, delayed or no revenue to us.

For example, each of EMD Serono and BMS elected not to continue the development of their licensed candidates based on strategic portfolio considerations.

For example, each of EMD Serono, BMS and Merck elected not to continue the development of their licensed candidates, and our existing collaborator, Astellas, decided not to nominate a third program under our collaboration;

each such decision was noted as based on strategic portfolio considerations.

Our collaborators may have other marketed products and product candidates under collaboration with other companies, including some of our competitors, and their corporate objectives may not be consistent with our best interests.

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Our collaborators may fail to live up to the terms of their agreements with us, which would require us to seek to enforce our agreements in accordance with the dispute resolution procedures set forth therein.

These procedures may require us to engage in litigation or arbitration to enforce our

rights, which can be expensive, time-consuming and distracting to our management and Board of Directors.

These procedures may require us to engage in litigation or arbitration to enforce our rights, which can be expensive, time-consuming and distracting to our management and Board of Directors.

Further, the type and timing of resolution of such disputes are difficult to predict;

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For example, such transactions may require us to incur non-recurring or other charges, increase our near- and long-term expenditures and pose significant integration or implementation challenges or disrupt our management or business.

These transactions would entail numerous operational and financial risks, including exposure to unknown liabilities, disruption of our business and diversion of our management’s time and attention in order to manage a collaboration or develop acquired products, product candidates or technologies, incurrence of substantial debt or dilutive issuances of equity securities to pay transaction consideration or costs, higher than expected collaboration, acquisition or integration costs, write-downs of assets or goodwill or impairment charges, increased amortization expenses, difficulty and cost in facilitating the collaboration or combining the operations and personnel of any acquired business, impairment of

relationships with key suppliers, manufacturers or customers of any acquired business due to changes in management and ownership and the inability to retain key employees of any acquired business.

Accordingly, although there can be no assurance that we will undertake or successfully complete any transactions of the nature described above, any transactions that we do complete may be subject to the foregoing or other risks and would have a material and adverse effect on our business, financial condition, results of operations and prospects.

Conversely, any failure to enter any additional collaboration or other strategic transaction that would be beneficial to us could delay the development and potential commercialization of our product candidates and have a negative impact on the competitiveness of any product candidate that reaches market.

Conversely, any failure to enter any additional collaboration or other strategic transaction that would be beneficial to us could delay the development and potential commercialization of our

product candidates and have a negative impact on the competitiveness of any product candidate that reaches market.

To date, no product developed on a cell-free manufacturing platform has received approval from the FDA, so the requirements for the manufacturing of products using our XpressCF ® and XpressCF+ ® platforms are uncertain.

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In this facility, we are developing and implementing novel, proprietary cell-free production technologies to supply our planned preclinical and clinical trials;

However, before we may initiate a clinical trial or commercialize any of our product candidates, we must demonstrate to the FDA that the chemistry, manufacturing and controls for our product candidates meet applicable requirements, and in the European Union, or EU, a manufacturing authorization must be obtained from the appropriate EU regulatory authorities.

The FDA has allowed clinical trial use of our product candidate luvelta, and our partner Merck’s MK-1484 product candidate, portions of which are manufactured in our San Carlos manufacturing facility;

however, we are transitioning our extract and reagent manufacturing strategy to an outsourced model and plan to wind down our manufacturing activities in our San Carlos facility no later than the end of 2025.

Before we may initiate a clinical trial or commercialize any of our product candidates, we must demonstrate to the FDA that the chemistry, manufacturing and controls for our product candidates meet applicable requirements, and in the European Union, or EU, a manufacturing authorization must be obtained from the appropriate EU regulatory authorities.

The FDA has allowed clinical trial use of our product candidates and others of our or our partners’ product candidates;

however, because no product manufactured on a cell-free manufacturing platform has yet been approved in the United States, there is no manufacturing facility that has demonstrated the ability to comply with FDA requirements for later stage clinical development or commercialization, and, therefore, the time frame for demonstrating compliance to the FDA’s satisfaction is uncertain.

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We do not have the ability to independently conduct all aspects of our preclinical testing or clinical trials ourselves.

We have accordingly relied in some cases and intend to rely in the future on third-party clinical investigators, clinical research organizations, or CROs, clinical data management organizations and consultants to assist or provide the design, conduct, supervision and monitoring of preclinical studies and clinical trials of our product candidates.

We have accordingly relied in some cases and intend to rely in the future on third-party clinical investigators, CROs, clinical data management organizations and consultants to assist or provide the design, conduct, supervision and monitoring of preclinical studies and clinical trials of our product candidates.

Because we intend to rely on these third parties and will not have the ability to conduct all preclinical studies or clinical trials independently, we will have less control over the timing, quality and other aspects of preclinical studies and clinical trials than we would have had we conducted them on our own.

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If we cannot contract with acceptable third parties on commercially reasonable terms, or at all, or if these third parties do not carry out their contractual duties, satisfy legal and regulatory requirements for the conduct of preclinical studies or clinical trials or meet expected deadlines, our clinical development programs could be delayed and otherwise adversely affected.

In all events, we will be responsible for ensuring that each of our

preclinical studies and clinical trials are conducted in accordance with the general investigational plan and protocols for the trial.

In all events, we will be responsible for ensuring that each of our preclinical studies and clinical trials are conducted in accordance with the general investigational plan and protocols for the trial.

The FDA requires preclinical studies to be conducted in accordance with good laboratory practices and clinical trials to be conducted in accordance with good clinical practices, including for designing, conducting, recording and reporting the results of preclinical studies and clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of clinical trial participants are protected.

Our reliance on third parties that we do not control will not relieve us of these responsibilities and requirements.

Our reliance on third parties that we do not control will not relieve us of these

responsibilities and requirements.

Any adverse development or delay in our preclinical studies or clinical trials as a result of our reliance on third parties could have a material and adverse effect on our business, financial condition, results of operations and prospects.

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To ensure timely and consistent product supply, we currently use a hybrid product supply approach wherein certain elements of our product candidates are manufactured internally at our manufacturing facilities in San Carlos, California, and other elements, including raw and intermediate materials, are manufactured at qualified third-party CMOs.

We intend to decommission or otherwise exit our manufacturing facility in San Carlos by the end of 2025 and rely on an external manufacturing strategy where all elements of our product candidates and platform reagents are manufactured by qualified third-party CMOs.

It is possible that our operations in the San Carlos facility will be negatively affected by the planned shutdown, impacting the amount or quality of our products made and potentially delaying our clinical trials or otherwise impacting our business.

Since our own manufacturing facilities may be limited or unable to manufacture certain of our preclinical and clinical trial product materials and supplies, we rely on third-party contract manufacturers to manufacture such clinical trial product materials and supplies for our or our collaborator’s needs.

For example, we have entered into a manufacturing agreement with EMD Millipore Corporation to perform conjugation of the applicable linker-warhead with the antibody component of our luvelta and STRO-003 product candidates.

We have also entered into agreements with Capua Bioservices, S.p.A.

and with AGC Biologics GmbH for the manufacture of certain reagents used in the manufacture of our products with our XpressCF ® and XpressCF+ ® platforms.

There can be no assurance that our preclinical and clinical development product supplies will not be limited, interrupted, or of satisfactory quality or continue to be available at acceptable prices.

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We expect to continue to rely on third-party manufacturers if we receive regulatory approval for any product candidate.

To the extent that we have existing, or enter into future, manufacturing arrangements with third parties,

we will depend on these third parties to perform their obligations in a timely manner consistent with contractual and regulatory requirements, including those related to quality control and assurance.

To the extent that we have existing, or enter into future, manufacturing arrangements with third parties, we will depend on these third parties to perform their obligations in a timely manner consistent with contractual and regulatory requirements, including those related to quality control and assurance.

If we are unable to obtain or maintain third-party manufacturing for product candidates, or to do so on commercially reasonable terms, we may not be able to develop and commercialize our product candidates successfully.

Our or a third party’s failure to execute on our manufacturing requirements and comply with cGMPs could adversely affect our business in a number of ways, including:

Our or a third party’s failure

to execute on our manufacturing requirements and comply with cGMPs could adversely affect our business in a number of ways, including:

• an inability to initiate or continue clinical trials of product candidates under development;

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For example, restrictions on travel imposed by governments, including China, or restrictions on person-in-plant permissions imposed by our contract manufacturers may limit the ability of our subject matter experts to visit our manufacturers and assist with technology transfers.

Further, legislation has been introduced in Congress to limit certain U.S.

biotechnology companies from using equipment or services produced or provided by select Chinese biotechnology companies, and others in Congress have advocated for the use of existing executive branch authorities to limit those Chinese service providers’ ability to engage in business in the U.S.

We cannot predict what actions may ultimately be taken with respect to trade relations between the United States and China or other countries, what products and services may be subject to such actions or what actions may be taken by the other countries in retaliation.

If we or our contract manufacturers were to encounter interruptions from any of these events or other unforeseen events, our ability to provide our product candidates to patients in clinical trials, or to provide product for treatment of patients once approved, would be jeopardized.

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If we are unable to adequately validate or scale-up the manufacturing process at our own manufacturing facilities or those of our current manufacturers, we will need to transfer to another manufacturer and complete the manufacturing validation process, which can be lengthy.

If we are able to adequately validate and scale-up the manufacturing process for our product candidates at our manufacturing facility or with a contract manufacturer, we will still need to negotiate with such contract manufacturer an agreement for commercial supply and it is not certain we will be able to come to agreement on terms acceptable to us.

manufacturer an agreement for commercial supply and it is not certain we will be able to come to agreement on terms acceptable to us.

The manufacture of biologics is complex and we or our third-party manufacturers may encounter difficulties in production.

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Moreover, if the FDA determines that our manufacturing facilities or those of our third-party manufacturers are not in compliance with FDA laws and regulations, including those governing cGMPs, the FDA may deny BLA approval until the deficiencies are corrected or we replace the manufacturer in our BLA with a manufacturer that is in compliance.

In addition, there are risks associated with large scale manufacturing for clinical trials or commercial scale including, among others, cost overruns, potential problems with process scale-up, process reproducibility, stability issues, compliance with cGMPs, lot consistency, timely availability of raw materials and other technical challenges.

In addition, there are risks associated with large scale manufacturing for clinical trials or commercial scale including, among others, cost overruns, potential problems with process scale-up, process reproducibility, stability issues, compliance with cGMPs and specifications, lot consistency, timely availability of raw materials and other technical challenges.

Even if we or our collaborators obtain regulatory approval for any of our product candidates, there is no assurance that manufacturers will be able to manufacture the approved product to specifications acceptable to the FDA or other regulatory authorities, to produce it in sufficient quantities to meet the requirements for the potential launch of the product or to meet potential future demand.

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As part of our process development efforts, we also may make changes to our manufacturing processes at various points during development, for various reasons, such as controlling costs, achieving scale, decreasing processing time, increasing manufacturing success rate or other reasons.

Such changes carry the risk that they will not achieve their intended objectives, and any of these changes could cause our product candidates to perform differently and affect the results of our ongoing clinical trials or future clinical trials.

Such changes carry the risk that they will not achieve their intended objectives, and any of these changes could cause our product candidates to

perform differently and affect the results of our ongoing clinical trials or future clinical trials.

In some circumstances, changes in the manufacturing process may require us to perform ex vivo comparability studies and to collect additional data from patients prior to undertaking more advanced clinical trials.

For instance, changes in our process during the course of clinical development may require us to show the comparability of the

product used in earlier clinical phases or at earlier portions of a trial to the product used in later clinical phases or later portions of the trial.

For instance, changes in our process during the course of clinical development may require us to show the comparability of the product used in earlier clinical phases or at earlier portions of a trial to the product used in later clinical phases or later portions of the trial.

We may not be successful in our efforts to use our XpressCF ® and XpressCF+ ® platforms to expand our pipeline of product candidates and develop marketable products.

The success of our business depends in large part upon our ability to identify, develop and commercialize products based on our XpressCF ® and XpressCF+ ® platforms.

Luvelta is our most advanced clinical stage program, and our preclinical and research programs may fail to identify other potential product candidates for clinical development for a number of reasons.

STRO-004 is our most advanced preclinical stage program, and our preclinical and research programs may fail to identify other potential product candidates for clinical development for a number of reasons.

Our research methodology may be unsuccessful in identifying potential product candidates or our potential product candidates may be shown to have harmful side effects or may have other characteristics that may make the products unmarketable or unlikely to receive marketing approval.

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If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

For example, in June 2023, we announced our Purchase Agreement with Blackstone.

For example, in June 2023, we announced our Purchase Agreement with Blackstone and in April 2024 we announced our License Agreement with Ipsen.

Failure to successfully validate, develop and obtain regulatory approval for companion diagnostics for our product candidates could harm our drug development strategy and operational results.

If companion diagnostics are developed in conjunction with clinical programs, the FDA may require regulatory approval of a companion diagnostic as a condition to approval of the product candidate.

For example, as we are developing luvelta for treatment of patients having ovarian cancer with elevated FolRα expression levels, we are likely to be required to obtain FDA approval or clearance of a companion diagnostic, concurrent with approval of luvelta, to test for elevated FolRα expression.

We do not have experience or capabilities in developing or commercializing diagnostics and plan to rely in large part on third parties to perform these functions.

We have entered into an agreement to develop diagnostic assays suitable for use as a companion diagnostic for luvelta.

Companion diagnostics are subject to regulation by the FDA and foreign regulatory authorities as medical devices and require separate regulatory approval or clearance prior to commercialization.

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Moreover, we also compete with current and future therapeutics developed at research-stage biotechnology companies, universities and other research institutions.

We are aware of several companies that are developing ADCs, cytokine derivatives, bispecific antibodies and cancer immunotherapies, including companies developing ADCs directed to the same target as luvelta.

For example, Immunogen recently received approval for a folate receptor α targeted ADC, mirvetuximab soravtansine (Elahere ® ).

In addition, large pharmaceutical companies and smaller biotechnology companies are developing other ADCs;

and we anticipate more FolRα-targeting ADCs and other potential FolRα-targeting modalities to be evaluated in the clinic in the coming years.

Further, other companies may develop ADCs targeting receptors other than folate receptor α for the treatment of the same indications for which we are developing luvelta.

For example, Pfizer has an approved ADC targeting TF, TIVDAK ® .

In addition, large pharmaceutical companies and smaller biotechnology companies are developing other ADCs, including TF-targeting ADCs;

and we anticipate more TF-targeting ADCs and other potential TF-targeting modalities to be evaluated in the clinic in the coming years.

Further, other companies may develop ADCs targeting receptors other than TF for the treatment of the same indications for which we are developing STRO-004.

Many of these companies are well-capitalized and, in contrast to us, have significant clinical experience, and may include our existing or future collaborators.

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In addition, numerous compounds are in clinical development for cancer treatment.

development pipeline for cancer includes small molecules, antibodies, vaccines, cell therapies and immunotherapies from a variety of companies and institutions.

The clinical development pipeline for cancer includes small molecules, antibodies, vaccines, cell therapies and immunotherapies from a variety of companies and institutions.

Further, if we successfully obtain approval for any product candidate, we will face competition based on many different factors, including the safety and effectiveness of our products, the ease with which our products can be administered and the extent to which patients accept relatively new routes of administration, the timing and scope of regulatory approvals for these products, the availability and cost of manufacturing, marketing and sales capabilities, price, reimbursement, coverage and patent position.

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Our future success will depend in large part on our continued ability to attract and retain other highly qualified scientific, technical and management personnel, as well as personnel with expertise in clinical testing, manufacturing, governmental regulation and commercialization.

We face competition for personnel from other companies, universities, public and private research institutions, government entities and other organizations.

We face competition for personnel from other companies, universities, public and private research institutions, government entities and other organizations, particularly in the San Francisco Bay Area, where we are headquartered.

Should our competitors recruit our key employees, our level of expertise and ability to execute our business plan would be negatively impacted.

Further, if we are unable to continue to attract and retain high-quality personnel, the rate and success at which we can discover and develop product candidates will be limited, which could have a material and adverse effect on our business, financial condition, results of operations and prospects.

In addition, job candidates and existing employees often consider the value of the stock awards they receive

in connection with their employment.

If the perceived benefits of our stock awards decline, either because we are a public company or for other reasons, it may harm our ability to recruit and retain highly-skilled employees.

employees may be more likely to leave us if the shares they own have significantly appreciated in value relative to

the original purchase prices of the shares, or if the exercise prices of the options that they hold are significantly

below the market price of our common stock, particularly after the expiration of the lock-up agreements described herein.

Moreover, in March 2025, management approved a restructuring plan with an associated reduction in workforce as a result of a review of current strategic priorities, resource allocation, and cost reduction intended to reduce operating costs, streamline operations and extend our cash runway.

These reductions in our workforce may also make retention of our current personnel both more important and more challenging.

These workforce reductions resulted in the loss of longer-term employees, the loss of institutional knowledge and expertise, and the reallocation and combination of certain roles and responsibilities across the organization, all of which could adversely affect our operations.

Given the complexity of our business, we must continue to implement and improve our managerial, operational and financial systems, manage our facilities and continue to recruit and retain qualified personnel.

Further, we recently underwent a leadership transition, which may be viewed negatively by employees, investors and/or our strategic partners.

Moreover, any attrition associated with this transition could significantly delay or prevent the achievement of product development and commercialization, and other business objectives, and adversely impact our stock price.

We will need to grow our organization, and we may experience difficulties in managing our growth and expanding our operations.

As of December 31, 2023, we had 302 full-time employees.

As of December 31, 2024, we had 310 full-time employees, prior to our March 2025 restructuring with an associated reduction in workforce, which resulted in a reduction of approximately 50% of our workforce.

As our development and commercialization plans and strategies develop, we expect to expand our employee base for managerial, operational, financial and other resources.

In addition, we have limited experience in product development and began our first clinical trial in 2018.

In addition, we have limited experience in product development.

As our product candidates enter and advance through preclinical studies and clinical trials, we will need to expand our development, regulatory and manufacturing capabilities or contract with other organizations to provide these capabilities for us.

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We currently have limited sales, marketing and distribution capabilities or experience.

If any of our product candidates are approved, we will need to develop additional internal sales, marketing and distribution capabilities

to commercialize such products, which would be expensive and time consuming, or enter into collaborations with third parties to perform these services.

If we decide to market our products directly, we will need to commit significant financial and managerial resources to develop a marketing and sales force with technical expertise and supporting distribution, administration and compliance capabilities.

If any of our product candidates are approved, we will need to develop additional sales, marketing and distribution capabilities to commercialize such products, which would be expensive and time consuming, or enter into collaborations with third parties to perform these services.

If we decide to market our products directly, we will need to commit significant financial and managerial resources to develop a marketing and sales force with technical expertise and support distribution, administration and compliance capabilities.

If we rely on third parties with such capabilities to market our products or decide to co-promote products with collaborators, we will need to establish and maintain marketing and distribution arrangements with third parties, and there can be no assurance that we will be able to enter into such arrangements on acceptable terms or at all.

In entering into third-party marketing or distribution arrangements, any revenue we receive will depend upon the efforts of the third parties and there can be no assurance that such third parties will establish adequate sales and distribution capabilities or be successful in gaining market acceptance of any approved product.

In entering third-party marketing or distribution arrangements, any revenue we receive will depend upon the efforts of the third parties and there can be no assurance that such third parties will establish adequate sales and distribution capabilities or be successful in gaining market acceptance or adoption of any approved product.

If we are not successful in commercializing any product approved in the future, either on our own or through third parties, our business, financial condition, results of operations and prospects could be materially and adversely affected.

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Political, economic and regulatory developments may further complicate pricing negotiations, and pricing negotiations may continue after reimbursement has been obtained.

Reference pricing used by various EU member states and parallel distribution, or arbitrage between low-priced and high-priced

member states, can further reduce prices.

Reference pricing used by various EU member states and parallel distribution, or arbitrage between low-priced and high-priced member states, can further reduce prices.

In some countries, we or current or future collaborators may be required to conduct a clinical trial or other studies that compare the cost-effectiveness of our therapeutic candidates to other available therapies in order to obtain or maintain reimbursement or pricing approval.

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Moreover, our employees are increasingly utilizing social media tools and our website as a means of communication.

Despite our efforts to monitor social media communications, there is risk that the unauthorized use of social media by our employees to communicate about our products or business, or any inadvertent disclosure of material, nonpublic information through these means, may result in violations of applicable laws and

regulations, which may give rise to liability and result in harm to our business.

In addition, there is also risk of inappropriate disclosure of sensitive information, which could result in significant legal and financial exposure and reputational damages that could potentially have a material adverse impact on our business, financial condition, results of operations and prospects.

Our employees could also inappropriately utilize artificial intelligence, or AI, in connection with their social media communications, introducing another potential source of reputational damage or other potential legal or financial exposure.

We depend on our information technology systems, and any failure of these systems, or those of our CROs, third-party vendors, or other contractors or consultants we may utilize, could harm our business.

Security breaches, cyber-attacks, loss of data, and other disruptions could compromise sensitive information related to our business or other personal information or prevent us from accessing critical information and expose us to liability, which could adversely affect our business, reputation, results of operations, financial condition and prospects.

We collect, use and store information in digital form that is necessary to conduct our business, and we are increasingly dependent on information technology systems and infrastructure to operate our business.

In the ordinary course of our business, we collect, use, store and transmit large amounts of confidential information, including intellectual property, proprietary business information health information, and personal information.

We have established physical, electronic and organizational measures designed to safeguard and secure our systems to prevent a data security incident (which may include, for example:

data breaches, viruses or other malicious code, coordinated attacks, data loss, phishing attacks, ransomware, denial of service attacks, or other security or information technology incidents caused by threat actors, technological vulnerabilities or human error), and rely on commercially available systems, software, tools, and monitoring to provide security for our information technology systems and the processing, transmission and storage of digital information.

We have also outsourced elements of our information technology infrastructure, and as a result, a number of third-party vendors may or could have access to our confidential information subject to contractual protections.

Our internal information technology systems and infrastructure, and those of our current and any future collaborators, CROs, third-party vendors, contractors and consultants and other third parties on which we rely, are vulnerable to damage from computer viruses, malware, natural disasters, terrorism, war, telecommunication and electrical failures, cyber-attacks or cyber-intrusions over the internet, attachments to emails, persons inside our organization, or persons with access to systems inside our organization.

We are increasingly dependent on information technology systems and infrastructure to operate our business.

In the ordinary course of our business, we collect, use, store and transmit large amounts of confidential and sensitive information, including intellectual property, proprietary business information and personal information (including health related information).

We have established physical, electronic and organizational measures designed to safeguard and secure our systems to prevent a security incident (which may include, for example:

data breaches, viruses or other malicious code, coordinated attacks, data loss, phishing attacks, ransomware, distributed denial of service attacks, or other security or information technology incidents caused by threat actors, technological vulnerabilities or human error), and rely on commercially available systems, software, tools, and monitoring to provide security for our information technology systems and the processing, transmission and storage of information.

We have also outsourced elements of our information technology infrastructure, and as a result, a number of third-party vendors have access to our information.

Despite the implementation of security measures, our internal information technology systems and infrastructure, and those of our current and any future collaborators, CROs, third-party vendors, contractors and consultants and other third parties on which we rely, are vulnerable to breach, breakdown, damage from computer viruses, malware, natural disasters, terrorism, war, telecommunication and electrical failures, cyber-attacks or cyber-intrusions over the internet, attachments to emails, persons inside our organization, or persons with access to systems inside our organization.

The risk of a formal security breach or disruption or data loss, particularly through cyber-attacks or cyber intrusion, including by computer hackers, foreign governments and cyber terrorists, has generally increased as the number, intensity and sophistication of attempted attacks and intrusions from around the world have increased.

For example, targeted deep fakes supported by sophisticated AI tools and other forms of impersonation of our executives are becoming increasingly prevalent.

In addition, the prevalent use of mobile devices that access confidential information increases the risk of data security breaches, which could lead to the loss of confidential information or other intellectual property.

The costs to us or our CROs or other contractors or consultants we may utilize to mitigate a data security incident and security vulnerabilities could be significant, and while we have implemented security measures designed to protect our data security and information technology systems, our efforts to address these problems may not be successful, and these problems could result in unexpected interruptions, delays, cessation of service and other harm to our business and our competitive position.

The costs to us or our collaborators, CROs, third party vendors, or contractors or consultants or other third parties on which we rely to mitigate a data security incident and security vulnerabilities could be significant, and while we have implemented security measures designed to protect our data security and information technology systems, our efforts to address these problems may not be successful, and these problems could result in unexpected interruptions, delays, cessation of service and other harm to our business and our competitive position.

We have incurred successful phishing attempts in the past, although we believe that these attempts were detected and neutralized without any compromise to our data and prior to any significant impact to our business.

We have also implemented measures to prevent such attacks, but we may still be subject to similar attacks in the future.

We are also aware of publicly disclosed security breaches at certain third parties on which we rely.

If such an event were to occur, whether to us or a third party on which we rely, and cause interruptions in our operations, it could result in a material disruption of our product development programs.

We are also aware of publicly disclosed security breaches at certain third parties on which we rely, though we believe that such security breaches did not compromise our data or materially impact our business.

Such security events, whether impacting our systems directly or impacting those of a third party on which we rely, could cause interruptions in our operations, and could result in a material disruption of our product development programs.

For example, the loss of clinical trial data from completed or ongoing or planned clinical trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data.

Further, if we are unable to generate or maintain access to essential patient samples or data for our research, development, and manufacturing activities for our programs, our business could be materially adversely affected.

Moreover, if a computer security breach affects our systems or results in the unauthorized release of personally identifiable information, our reputation could be materially damaged.

Such a breach may require formal notification to governmental agencies, the media or individuals pursuant to various federal and state privacy and security laws, such as the Health Insurance Portability and Accountability Act of 1996, or HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009, or HITECH, and its implementing rules and regulations, regulations promulgated by the Federal Trade Commission and state breach

notification laws.

We also may be subject to global privacy laws, such as Europe’s General Data Protection Regulation, or GDPR.

We would also be exposed to a risk of loss or litigation and potential liability under laws, regulations and contracts that protect the privacy and security of personal information that may result in regulatory scrutiny, fines, private right of action settlements, and other consequences.

Compliance with these and any other applicable privacy and data security laws and regulations is a rigorous and time-intensive process, and we may be required to put in place additional mechanisms ensuring compliance with the new data protection rules and possible government oversight.

Moreover, if a computer security breach affects our systems or results in the unauthorized release of personally information, our reputation could be materially damaged, we may be required to formally notify governmental agencies, the media or individuals pursuant to various federal and state privacy and security laws.

We could also be exposed to a risk of loss or litigation and potential liability under laws, regulations and contracts that protect the privacy and security of personal information that may result in regulatory scrutiny, fines, private right of action settlements, and other consequences.

Compliance with applicable privacy and data security laws and regulations is a rigorous and time-intensive process, and we may be required to put in place additional mechanisms ensuring compliance with the new data protection rules and possible government oversight.

Our failure to comply with such laws or to adequately secure the information we hold could result in significant liability or reputational harm and, in turn, a material adverse effect on our client base, member base and revenue.

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A significant disruption in the availability of our information technology and other internal infrastructure systems could cause interruptions and delays in our research and development and manufacturing work.

In addition, some of our employees work remotely from time to time, which presents certain risks to our business.

Further, some of our employees work remotely from time to time, which presents certain risks to our business.

For example, remote work presents significant demands on our information technology resources and systems and can be at risk for phishing and other malicious activity, which can result in an increase to the number of points of potential exposure, such as laptops and mobile devices, that need to be secured.

Any failure to effectively manage these risks, including to timely identify and appropriately respond to any security incidents, may adversely affect our business.

In our ongoing efforts to innovate and optimize operational efficiency, we have integrated artificial intelligence, or AI, into various aspects of our workplace.

For example, we are implementing AI machine learning for email behavioral monitoring.

In our ongoing efforts to innovate and optimize operational efficiency, we have integrated AI into various aspects of our workplace.

For example, we have implemented AI machine learning for email behavioral monitoring.

While AI presents opportunities for enhanced productivity and innovation, it also introduces inherent risks, including legal and regulatory, that could adversely impact our business and reputation.

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The rapidly evolving regulatory landscape surrounding AI also poses a risk, as new laws and regulations could impose additional compliance burdens, resulting in increased operational costs.

We are committed to implementing robust governance and control mechanisms to mitigate these risks, but there can be no assurance that such measures will adequately prevent or mitigate the adverse effects that the integration and use of AI may have on our business, financial condition, and results of operations.

We are committed to implementing robust governance and control mechanisms to mitigate these risks, but there can be

no assurance that such measures will adequately prevent or mitigate the adverse effects that the integration and use of AI may have on our business, financial condition, and results of operations.

If we do not comply with laws regulating the protection of the environment and health and human safety, our business could be affected adversely.

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We are also subject to numerous environmental, health and workplace safety laws and regulations, including those governing laboratory procedures, exposure to blood-borne pathogens and the handling of animals and biohazardous materials.

Although we maintain workers’ compensation insurance to cover

us for costs and expenses we may incur due to injuries to our employees resulting from the use of these materials or from other hazards potentially present in our workplaces, such as high voltage electricity, process steam or other hot material, liquid nitrogen or other cold material, materials stored under pressure, laboratory instruments that incorporate powerful lasers or magnets, sonic resonance, heavy machinery, and the like, this insurance may not provide adequate coverage against potential liabilities.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of these materials or from other hazards potentially present in our workplaces, such as high voltage electricity, process steam or other hot material, liquid nitrogen or other cold material, materials stored under pressure, laboratory instruments that incorporate powerful lasers or magnets, sonic resonance, heavy machinery, and the like, this insurance may not provide adequate coverage against potential liabilities.

While we maintain pollution legal liability insurance for our manufacturing facility in San Carlos, California, we do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological or hazardous materials in our other locations.

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However, in the event of an accident or incident at these facilities, we cannot assure you that the amounts of insurance will be sufficient to satisfy any damages and losses.

In addition, the long-term effects of climate change on general economic conditions and the pharmaceutical industry in particular are unclear, and

may heighten or intensify existing risk of natural disasters.

In addition, the long-term effects of climate change on general economic conditions and the pharmaceutical industry in particular are unclear, and may heighten or intensify existing risk of natural disasters.

If our facilities, or the manufacturing facilities of our third-party contract manufacturers, are unable to operate because of an accident or incident or for any other reason, even for a short period of time, any or all of our research and development programs may be harmed.

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Further, existing tax laws, statutes, rules, regulations or ordinances could be interpreted, changed, modified or applied adversely to us.

For example, legislation enacted in 2017, informally titled the Tax Cuts and Jobs Act, or the 2017 Tax Act, enacted many significant changes to the U.S.

Beginning in 2022, the 2017 Tax Act eliminates the option to currently deduct research and development expenditures and requires taxpayers to capitalize and amortize U.S.

For example, legislation enacted in 2017, informally titled the Tax Cuts and Jobs Act, or 2017 Tax Act, enacted many significant changes to the U.S.

Beginning in 2022, the 2017 Tax Act eliminated the option to currently deduct research and development expenditures and instead required taxpayers to capitalize and amortize U.S.

based and non-U.S.

based research and development expenditures over five and fifteen years, respectively, pursuant to IRC Section 174.

Although there have been legislative proposals to repeal or defer the capitalization requirement to later years, there can be no assurance that the provision will be repealed or otherwise modified.

Although there have been legislative proposals to repeal the capitalization requirement or limit it to non-U.S.

based research, there can be no assurance that the provision will be repealed or otherwise modified.

We also cannot predict whether, when, in what form, or with what effective dates, tax laws, regulations and rulings may be enacted, promulgated or issued, which could result in an increase in our or our stockholders’ tax liability or require changes in the manner in which we operate in order to minimize or mitigate any adverse effects of changes in tax law.

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Our ability to use net operating loss carryforwards to offset taxable income could be limited.

Under current law, our net operating loss carryforwards generated in tax years ending on or prior to December 31, 2017, are permitted to be carried forward for 20 years and our federal net operating losses generated in tax years beginning after December 31, 2017, may be carried forward indefinitely, but the deductibility of such federal net operating losses, is limited to 80% of taxable income (without regard to certain deductions).

generated in tax years beginning after December 31, 2017, may be carried forward indefinitely, but the deductibility of such federal net operating losses, is limited to 80% of taxable income (without regard to certain deductions).

In addition, under Section 382 of the U.S.

Internal Revenue Code of 1986, as amended, and corresponding provisions of state law, if we experience an “ownership change” which is generally defined as a greater than 50% change, by value, in its equity ownership over a three-year period, our ability to use our pre-change net operating loss carryforwards to offset our post-change income may be limited.

Based on Section 382 studies performed for certain prior periods, we experienced an ownership change on November 20, 2019 and December 31, 2022, which imposed limitations on the use of our net operating losses arising before that date.

In addition, we may have experienced other ownership changes in the past and may also experience ownership changes in the future as a result of equity offerings or other shifts in our stock ownership, some of which are outside our control.

As a result, our use of federal NOL carryforwards could be limited.

Internal Revenue Code of 1986, as amended, and corresponding provisions of state law, if we experience an “ownership change” which is generally defined as a greater than 50% change, by value, in our equity ownership over a three-year period, our ability to use our pre-change net operating loss carryforwards to offset our post-change income may be limited.

Based on Section 382 studies performed for certain prior periods, we experienced ownership change on each of November 20, 2019 and December 31, 2022, which imposed limitations on the use of our net operating losses arising before those dates.

In addition, we may have experienced other ownership changes in the past and may experience ownership changes in the future as a result of equity offerings or other shifts in our stock ownership, some of which are outside our control.

As a result, our use of federal NOL carryforwards could be further limited.

State net operating loss carryforwards may be similarly limited.

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Any such limitations may result in greater tax liabilities than we would incur in the absence of such limitations and any increased liabilities could adversely affect our business, results of operations, financial position and cash flows.

Our investment in Vaxcyte is subject to risk

As of December 31, 2023, we held Vaxcyte common stock with a fair value of $41.9 million.

Vaxcyte common stock is publicly traded and therefore subject to the various risk factors associated with any publicly traded company, including risks associated with Vaxcyte’s business, its business outlook, cash flow requirements and financial performance, the state of the market and the general economic climate, including the impact of health pandemics, regional geopolitical conflicts, changes in interest rates, inflation, potential uncertainty with respect to the debt ceiling and potential government shutdowns related thereto.

Vaxcyte common stock has been subject to substantial volatility, and the change in fair value of our interests in Vaxcyte will materially impact our reported net income or net loss in our financial statements.

Our cash and investments could be adversely affected if the financial institutions in which we hold our cash and investments fail.

We regularly maintain cash balances at third-party financial institutions in excess of the FDIC insurance limit and similar regulatory insurance limits outside the United States and governments may not guarantee all depositors if such financial institutions were to fail, as the U.S.

government did in 2023 with Silicon Valley Bank depositors, in the event of further bank closures and continued instability in the global banking system.

We regularly maintain cash balances at third-party financial institutions in excess of the FDIC insurance limit and similar regulatory insurance limits outside the United States, and governments may not guarantee all depositors if such financial institutions were to fail, in the event of bank closures and continued instability in the global banking system.

Any future adverse developments in the global banking system could directly or indirectly negatively impact our business, financial condition, results of operations and prospects.

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Generally accepted accounting principles in the United States, or U.S.

GAAP, are subject to interpretation by the Financial Accounting Standards Board, or the FASB, the American Institute of Certified Public Accountants, the SEC and various bodies formed to promulgate and interpret appropriate accounting principles.

GAAP, are subject to interpretation by the Financial Accounting Standards Board, or FASB, the American Institute of Certified Public Accountants, the SEC and various bodies formed to promulgate and interpret appropriate accounting principles.

For example, in May 2014, the FASB issued accounting standards update No.

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Additionally, the implementation of this guidance or a change in other principles or interpretations could have a significant effect on our financial results, and could affect the reporting of transactions completed before the announcement of a change.

Furthermore, we have adopted Topic 606 through the modified retrospective method.

This will impact the comparability of our financial results, which might lead investors to draw incorrect conclusions that could harm investor interest in holding or purchasing our equity.

Risks Related to Intellectual Property

If we are not able to obtain, maintain and enforce sufficient patent and other intellectual property protection for our technologies or product candidates, development and commercialization of our product candidates may be adversely affected.

Our success depends in part on our, our licensor’s and our collaborators’ ability to obtain and maintain patents and other forms of intellectual property rights, including in-licenses of intellectual property rights of others, for our product candidates, methods used to manufacture our product candidates and methods for treating patients using our product candidates, as well as our ability to preserve our trade secrets, to prevent third parties from infringing upon our proprietary rights and to operate without infringing upon the proprietary rights of others.

Our success depends in part on our, our licensor’s and our collaborators’ ability to obtain and maintain patents and other forms of intellectual property rights, including in-licenses of intellectual property rights of others that cover our product candidates, methods used to manufacture our product candidates, methods for treating patients using our product candidates, pharmaceutical formulations and dosing regimens, as well as our ability to

preserve our trade secrets, to prevent third parties from infringing upon our proprietary rights and to operate without infringing upon the proprietary rights of others.

We, our licensors and collaborators may not be able to apply for patents on certain aspects of our product candidates in a timely fashion or at all.

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If our licensors, licensees or collaborators are not fully cooperative or disagree with us as to the prosecution, maintenance or enforcement of any patent rights, such patent rights could be compromised.

Also, although we enter into non-disclosure and confidentiality agreements with parties who have access to confidential or

patentable aspects of our research and development output, such as our employees, collaborators, CROs, contract manufacturers, consultants, advisors and other third parties, any of these parties may breach the agreements and disclose such output before a patent application is filed, thereby jeopardizing our ability to seek patent protection.

Also, although we enter into non-disclosure and confidentiality agreements with parties who have access to confidential or patentable aspects of our research and development output, such as our employees, collaborators, CROs, contract manufacturers, consultants, advisors and other third parties, any of these parties may breach the agreements and disclose such output before a patent application is filed, thereby jeopardizing our ability to seek patent protection.

In addition, publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all.

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Composition of matter patents for biological and pharmaceutical therapeutic candidates often provide a strong form of intellectual property protection for those types of products, as such patents provide protection without regard to any method of use.

We cannot be certain that the claims in our pending patent applications directed to composition of matter of our therapeutic candidates will be considered patentable by the United States Patent and Trademark Office (USPTO) or by patent offices in foreign countries, or that the claims in any of our issued patents will be considered valid and enforceable by courts in the United States or foreign countries.

We cannot be certain that the claims in our pending patent applications directed to composition of matter of our therapeutic candidates will be considered patentable by the United States Patent and Trademark Office, or USPTO, or by patent offices in foreign countries, or that the claims in any of our issued patents will be considered valid and enforceable by courts in the United States or foreign countries.

Method of use patents protect the use of a product for the specified method.

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If third parties disclose or misappropriate our proprietary rights, it may materially and adversely affect our position in the market.

Patent and Trademark Office, or USPTO, and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other provisions during the patent process.

The USPTO, and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other provisions during the patent process.

There are situations in which noncompliance can result in abandonment or lapse of a patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction.

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As such, we do not know the degree of future protection that we will have on our proprietary products and technology.

While we will endeavor to try to protect our product candidates with intellectual property rights such as patents, as appropriate, the process of obtaining patents is time consuming, expensive and sometimes unpredictable.

While we will endeavor to try to protect our product candidates with

intellectual property rights such as patents, as appropriate, the process of obtaining patents is time consuming, expensive and sometimes unpredictable.

Once granted, patents may remain open to opposition, interference, re-examination, post-grant review, inter partes review, nullification or derivation action in court or before patent offices or similar proceedings for a given period after allowance or grant, during which time third parties can raise objections against such initial grant.

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These rights may permit the government to disclose our confidential information to third parties or allow third parties to use our licensed technology.

The government can also exercise its march-in rights if it determines that action is necessary because we fail to achieve practical application of the government-funded technology, because action is necessary to alleviate health or safety needs, to meet requirements of federal regulations, or to give preference to U.S.

In addition, the United States federal government retains certain rights in inventions produced with its financial assistance under the Patent and Trademark Law Amendments Act, or the Bayh-Dole Act.

The federal government retains a “nonexclusive, nontransferable, irrevocable, paid-up license” for its own benefit.

The Bayh-Dole Act also provides federal agencies with “march-in rights.” The government can exercise its march-in rights if it determines that action is necessary because we fail to achieve practical application of the government-funded technology, because action is necessary to alleviate health or safety needs, to meet requirements of federal regulations, or to give preference to U.S.

In addition, our rights in such inventions may be subject to certain requirements to manufacture products embodying such inventions in the United States.

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We have obtained grants and issuances of, and have obtained a license from a third party on an exclusive basis to, patents related to our proprietary XpressCF ® and XpressCF+ ® platforms.

The issued patents and pending patent applications in the United States and in key markets around the world that we own or license claim many different methods, compositions and processes relating to the discovery, development, manufacture and commercialization of antibody-based and other therapeutics.

As the field of antibody-based therapeutics continues to mature, patent applications are being processed by national patent offices around the world.

As the field of antibody-drug conjugate therapeutics continues to mature, patent applications are being processed by national patent offices around the world.

There is uncertainty about which patents will issue and, if they do, as to when, to whom, and with what claims.

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This could make it difficult for us or our licensors or collaborators to prevent the infringement of our or their patents or marketing of competing products in violation of our or their proprietary rights generally in certain jurisdictions.

Proceedings to enforce our patent rights in foreign jurisdictions could result in substantial cost and divert our and our licensors’ or collaborators’ efforts and attention from other aspects of our business, could put our and our licensors’ or collaborators’ patents at risk of being invalidated or interpreted narrowly and our and our licensors’ or collaborators’ patent applications at risk of not issuing and could provoke third parties to assert claims against us or our licensors or collaborators.

claims against us or our licensors or collaborators.

We or our licensors or collaborators may not prevail in any lawsuits that we or our licensors or collaborators initiate, and the damages or other remedies awarded, if any, may not be commercially meaningful.

We generally file a provisional patent application first (a priority filing) at the USPTO.

An international application under the Patent Cooperation Treaty, PCT, is usually filed within twelve months after the priority filing.

An international application under the Patent Cooperation Treaty, or PCT is usually filed within twelve months after the priority filing.

Based on the PCT filing, national and regional patent applications may be filed in the United States, EU, Japan, Australia and Canada and, depending on the individual case, also in any or all of, inter alia, Brazil, China, Hong Kong, India, Israel, Mexico, New Zealand, South Africa, South Korea and other jurisdictions.

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For example, the United States and foreign government actions related to Russia’s invasion of Ukraine may limit or prevent filing, prosecution and maintenance of patent applications in Russia.

actions may also prevent maintenance of issued patents in Russia.

Government actions may also prevent maintenance of issued patents in Russia.

These actions could result in abandonment or lapse of patents or patent applications, resulting in partial or complete loss of patent rights in Russia.

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As the UPC is a new court system, there is very limited precedent for the court, increasing the uncertainty of any litigation.

As a single court system can invalidate a European patent, we, our licensors or our collaborators, may opt out of the UPC and as such, each European patent would need to be challenged in each individual country.

Limited information is available to make judgments about advantages and disadvantages of either opting into or remaining out of UPC jurisdiction;

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Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation.

There could also be public announcements of the results

of hearings, motions, or other interim proceedings or developments.

There could also be public announcements of the results of hearings, motions, or other interim proceedings or developments.

If securities analysts or investors perceive these results to be negative, it could have a material adverse effect on the price of our common stock.

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Patent applications in the United States and elsewhere are typically published approximately 18 months after the earliest filing for which priority is claimed, with such earliest filing date being commonly referred to as the priority date.

applications that will not be filed outside the U.S.

applications that will not

be filed outside the U.S.

can remain confidential until patents issue.

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Intellectual property rights of third parties could adversely affect our ability to commercialize our product candidates, and we, our licensors or collaborators, or any future strategic partners may become subject to third party claims or litigation alleging infringement of patents or other proprietary rights or seeking to invalidate patents or other proprietary rights.

We might be required to litigate or obtain

licenses from third parties in order to develop or market our product candidates.

We might be required to litigate or obtain licenses from third parties in order to develop or market our product candidates.

Such litigation or licenses could be costly or not available on commercially reasonable terms.

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For example, one of our European patents related to technology auxiliary to our XpressCF ® platform is involved in an opposition proceeding at the European Patent Office, or EPO, and was revoked by the EPO in 2021.

In April 2022, an appeal was filed;

the process for this appeal is ongoing.

This may prevent us from asserting this patent against our competitors practicing otherwise infringing methods in relevant European countries where this patent has been granted.

In April 2022, an appeal was filed and in 2024, the Opposition Division decided to maintain our European Patent in amended form.

Absent our successful appeal, we would not be able to assert this patent against our competitors practicing otherwise infringing methods in relevant European countries where this patent has been granted.

There are many issued and pending patents that might claim aspects of our product candidates and modifications that we may need to apply to our product candidates.

There are also many issued patents that claim antibodies, portions of antibodies, cytokines, half-life extending polymers, linkers, cytotoxins, or other warheads that may be relevant for the products we wish to develop.

There are also many issued patents that claim antibodies, portions of antibodies, linkers, cytotoxins, immunostimulants, or other warheads, or combinations thereof, that may be relevant for the products we wish to develop.

Thus, it is possible that one or more organizations will hold patent rights to which we will need a license.

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Even if a license can be obtained on acceptable terms, the rights may be non-exclusive, which could give our competitors access to the same technology or intellectual property rights licensed to us.

If we fail to obtain a required license, we or our existing or future collaborators may be unable to effectively market product candidates based on our technology, which could limit our ability to generate revenue or achieve profitability and possibly prevent us from generating revenue sufficient to sustain our operations.

If we fail to obtain a required license, we or our existing or

future collaborators may be unable to effectively market product candidates based on our technology, which could limit our ability to generate revenue or achieve profitability and possibly prevent us from generating revenue sufficient to sustain our operations.

In addition, we may find it necessary to pursue claims or initiate lawsuits to protect or enforce our patent or other intellectual property rights.

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Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could delay our research and development efforts and limit our ability to continue our operations.

Because the antibody-based therapeutics landscape is still evolving, it is difficult to conclusively assess our freedom to operate without infringing on third-party rights.

Because the antibody-drug conjugate therapeutics landscape is still evolving, it is difficult to conclusively assess our freedom to operate without infringing on third-party rights.

There are numerous companies that have pending patent applications and issued patents broadly covering antibodies generally, covering antibodies directed against the same targets as, or targets similar to, those we are pursuing, or covering linkers and cytotoxic warheads similar to those that we are using in our product candidates.

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We are further aware of an issued patent, expected to expire in 2034, relating to certain conjugates comprising a genus of hemiasterlin derivatives that may be potentially relevant to products incorporating our hemiasterlin-derived linker-warhead.

If any of these patents are valid and not yet expired when, and if, we receive marketing approval for luvelta, as applicable, we may need to seek a license to one or more of these patents, each of which may not be available on commercially reasonable terms or at all.

Failure to receive a license to any of these patents, or other potentially relevant patents currently unknown to us, could delay commercialization of any or all of luvelta, STRO-003 or STRO-004.

If any of these patents are valid and not yet expired when, and if, we receive marketing approval for STRO-004, as applicable, we may need to seek a license to one or more of these patents, each of which may not be available on commercially reasonable terms or at all.

Failure to receive a license to any of these patents, or other potentially relevant patents currently unknown to us, could delay commercialization of STRO-004 or any other product candidate.

Our competitive position may suffer if patents issued to third parties or other third-party intellectual property rights cover our products or product candidates or elements thereof, or our manufacture or uses relevant to our development plans.

into a license agreement with the intellectual property right holder, if available on commercially reasonable terms.

In such cases, we may not be in a position to develop or commercialize products or product candidates until such patents expire or unless we successfully pursue litigation to nullify or invalidate the third-party intellectual property right concerned, or enter into a license agreement with the intellectual property right holder, if available on commercially reasonable terms.

There may be issued patents of which we are not aware, held by third parties that, if found to be valid and enforceable, could be alleged to be infringed by our XpressCF ® and XpressCF+ ® platforms and related technologies and product candidates.

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It is also possible that we have failed to identify relevant third-party patents or applications.

For example, U.S.

applications filed before November 29, 2000, and certain U.S.

applications filed after that date that will not be filed outside the United States remain confidential until patents issue.

Patent applications in the United States and elsewhere are published approximately 18 months after the earliest filing for which priority is claimed, with such earliest filing date being commonly referred to as the priority date.

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We might, if possible, also be forced to redesign product candidates so that we no longer infringe the third-party intellectual property rights.

Any of these events, even if we were ultimately to prevail, could require us to divert substantial financial and management resources that we would otherwise be able to devote to our business and could have a material and adverse effect on our business, financial condition, results of operations and prospects.

Any of these events, even if we

were ultimately to prevail, could require us to divert substantial financial and management resources that we would otherwise be able to devote to our business and could have a material and adverse effect on our business, financial condition, results of operations and prospects.

Intellectual property litigation could cause us to spend substantial resources and distract our personnel from their normal responsibilities.

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If we fail in defending such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel.

A loss of key research personnel or their work product

could hamper our ability to commercialize, or prevent us from commercializing, our product candidates, which could severely harm our business.

A loss of key research personnel or their work product could hamper our ability to commercialize, or prevent us from commercializing, our product candidates, which could severely harm our business.

Even if we are successful in defending against these claims, litigation could result in substantial costs and be a distraction to management.

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As a result, our revenue from applicable products could be reduced.

Further, if this occurs, our competitors may take advantage of our investment in development and trials by referencing our clinical and preclinical data and launch their product earlier than might otherwise be the case, and our competitive position, business, financial condition, results of operations and prospects could be materially harmed.

Further, if this occurs, our competitors may take advantage of our investment in

development and trials by referencing our clinical and preclinical data and launch their product earlier than might otherwise be the case, and our competitive position, business, financial condition, results of operations and prospects could be materially harmed.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

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jurisdictions could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement or defense of issued patents.

In the United States, numerous recent changes to the patent laws and

proposed changes to the rules of the USPTO that may have a significant impact on our ability to protect our technology and enforce our intellectual property rights.

In the United States, numerous recent changes to the patent laws and proposed changes to the rules of the USPTO that may have a significant impact on our ability to protect our technology and enforce our intellectual property rights.

For example, the America Invents Act, enacted within the last several years involves significant changes in patent legislation.

Supreme Court has ruled on several patent cases in recent years, some of which cases either narrow the scope of patent protection available in certain circumstances or weaken the rights of patent owners in certain situations.

For example, the decision by the U.S.

For example, the Supreme Court of the United States held in Amgen v.

Sanofi (2023) that a functionally claimed genus was invalid for failing to comply with the enablement requirement of the Patent Act.

In addition, the Federal circuit issued a decision, In re Cellect, LLC (2023) involving the interaction of patent term adjustment (PTA), terminal disclaimers, and obvious-type double patenting which may affect the patent term of any issued patents that rely on any PTA.

Depending on future actions by the U.S.

Congress, the U.S.

courts, the USPTO and the relevant law-making bodies in other countries, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future.

Also, the decision by the U.S.

Supreme Court in Association for Molecular Pathology v.

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Congress, the federal courts and the USPTO, and similar legislative and regulatory bodies in other countries in which we may pursue patent protection, the laws and regulations governing patents could change in unpredictable ways that would weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future .

We may become subject to claims challenging the inventorship or ownership of our patents and other intellectual property.

For example, the Inflation Reduction Act, or IRA, passed by Congress authorizes the Secretary of the U.S.

Department of Health and Human Services, or HHS, to negotiate prices directly with participating manufacturers for selected medicines reimbursed by Medicare Part B or Part D even if these medicines are protected by an existing patent.

In addition, we may become subject to claims challenging the inventorship or ownership of our patents and other intellectual property.

We may be subject to claims that former employees, collaborators or other third parties have an interest in our patents or other intellectual property as an inventor or co-inventor.

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Although some of our employees have experience in conducting and managing clinical trials from prior employment at other companies, we, as a company, have no prior experience in conducting and managing the clinical trials necessary to obtain regulatory approvals, including approval by the FDA.

The time required to obtain FDA and other approvals is unpredictable but typically takes many years following the commencement of clinical trials, depending upon the type, complexity and novelty of the product candidate, and may be further delayed due to one or more temporary federal government shutdowns.

The time required to obtain

FDA and other approvals is unpredictable but typically takes many years following the commencement of the initial clinical trials, depending upon the type, complexity and novelty of the product candidate and the availability of applicable government resources.

The standards that the FDA and its foreign counterparts use when regulating us require judgment and can change, which makes it difficult to predict with certainty their application.

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It is impossible to predict whether legislative changes will be enacted, or whether FDA or foreign regulations, guidance or interpretations will be changed, or the impact of such changes, if any.

For example, the Oncology Center of Excellence within the FDA has recently advanced Project Optimus, which is an initiative to reform the dose optimization and dose selection paradigm in oncology drug development to emphasize selection of an optimal dose, which is a dose or doses that maximizes not only the efficacy of a drug but the safety and tolerability as well.

For example, the Oncology Center of Excellence within the FDA has advanced Project Optimus, which is an initiative to reform the dose optimization and dose selection paradigm in oncology drug development to emphasize selection of an optimal dose, which is a dose or doses that maximizes not only the efficacy of a drug but the safety and tolerability as well.

This shift from the prior approach, which generally determined the maximum tolerated dose, may require sponsors to spend additional time and resources to further explore a product candidate’s dose-response relationship to facilitate optimum dose selection in a target population.

Other recent Oncology Center of Excellence initiatives have included Project FrontRunner, a new initiative with a goal of developing a framework for identifying candidate drugs for initial clinical development in the earlier advanced setting rather than for treatment of patients who have received numerous prior lines of therapies or have exhausted available treatment options.

Other Oncology Center of Excellence initiatives have included Project FrontRunner, an initiative with a goal of developing a framework for identifying candidate drugs for initial clinical development in the earlier advanced setting rather than for treatment of patients who have received numerous prior lines of therapies or have exhausted available treatment options.

We are considering these policy changes as they relate to our programs.

We may also be affected by ex-US regulatory requirements, given that our trials may be conducted globally;

current and unforeseen new EU-specific clinical trial conduct regulations, such as IVDR and GDPR, may delay, or increase the difficulty and expense of conducting, our clinical studies.

current and unforeseen new EU-specific clinical trial conduct regulations, such as the In Vitro Diagnostic Regulation, or IVDR, and GDPR, may delay, or increase the difficulty and expense of conducting, our clinical studies.

Given that the product candidates we are developing, either alone or with our collaborators, represent a new approach to the manufacturing and type of therapeutic biologics, the FDA and its foreign counterparts have not yet established any definitive policies, practices or guidelines in relation to these product candidates.

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Furthermore, any regulatory approval to market a product may be subject to limitations on the approved uses for which we may market the product or on the labeling or other restrictions.

In addition, the FDA has the authority to require a risk

evaluation and mitigation strategy, or REMS, as part of a BLA or after approval, which may impose further requirements or restrictions on the distribution or use of an approved biologic, such as limiting prescribing to certain physicians or medical centers that have undergone specialized training, limiting treatment to patients who meet certain safe-use criteria and requiring treated patients to enroll in a registry.

In addition, the FDA has the authority to require a risk evaluation and mitigation strategy, or REMS, as part of a BLA or after approval, which may impose further requirements or restrictions on the distribution or use of an approved biologic, such as limiting prescribing to certain physicians or medical centers that have undergone specialized training, limiting treatment to patients who meet certain safe-use criteria and requiring treated patients to enroll in a registry.

These limitations and restrictions may limit the size of the market for the product and affect reimbursement by third-party payors.

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The FDA has significant post-market authority, including the authority to require labeling changes based on new safety information and to require post-market studies or clinical trials to evaluate safety risks related to the use of a product or to require withdrawal of the product from the market.

The FDA also has the authority to require a REMS plan after approval, which may impose further requirements or restrictions on the distribution or use of an approved drug or therapeutic biologic.

The FDA also has the authority to require a REMS after approval, which may impose further requirements or restrictions on the distribution or use of an approved drug or therapeutic biologic.

The manufacturing facilities we use to make a future product, if any, will also be subject to periodic review and inspection by the FDA and other regulatory agencies, including for continued compliance with cGMP requirements.

The discovery of any new or previously unknown problems with our third-party manufacturers, manufacturing processes or facilities may result in restrictions on the product, manufacturer or facility, including withdrawal of the product from the market.

on third-party manufacturers, we will not have control over compliance with applicable rules and regulations by such manufacturers.

If we rely on third-party manufacturers, we will not have control over compliance with applicable rules and regulations by such manufacturers.

Any product promotion and advertising will also be subject to regulatory requirements and continuing regulatory review.

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If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained and we may not achieve or sustain profitability, which would adversely affect our business.

We also cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad.

The ability of the FDA to review and approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s ability to perform routine functions.

Moreover, the ability of the FDA to review and approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s ability to perform routine functions.

In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable.

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Delays in filling or replacing key positions could significantly impact the ability of the FDA and other agencies to fulfill their functions, and could greatly impact healthcare and the pharmaceutical industry.

If a prolonged government shutdown occurs, or if global health concerns prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews, or other regulatory activities, it could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

We also cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad.

Further, three decisions from the U.S.

Supreme Court in 2024 may lead to an increase in litigation against regulatory agencies that could create uncertainty and thus negatively impact our business.

The first decision overturned established precedent that required courts to defer to regulatory agencies’ interpretations of ambiguous statutory language.

The second decision overturned regulatory agencies’ ability to impose civil penalties in administrative proceedings.

The third decision extended the statute of limitations within which entities may challenge agency actions.

However, the specific, lasting effects of these decisions, which may vary within different judicial districts and circuits, is unknown.

We also cannot predict the extent to which FDA and SEC regulations, policies, and decisions may become subject to increasing legal challenges, delays, and changes.

For example, these cases may result in increased litigation by companies against the FDA, and impact the FDA’s authority, lead to uncertainties in the industry, and disrupt the FDA’s normal operations, which could impact the timely review of any regulatory filings or applications we submit to the FDA.

Further, if a prolonged government shutdown occurs, or if global health concerns prevent the FDA or other regulatory authorities from conducting their regular inspections, reviews, or other regulatory activities, it could significantly impact the ability of the FDA or other regulatory authorities to timely review and process our regulatory submissions, which could have a material adverse effect on our business.

We may face difficulties from healthcare legislative reform measures.

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In addition, other legislative changes have been proposed and adopted in the United States federal and state levels to reduce healthcare expenditures, including the Budget Control Act, which, subject to certain temporary suspension periods, imposed 2% reductions in Medicare payments to providers per fiscal year starting April 1, 2013 and, due to subsequent legislative amendments to the statute, that will remain in effect through 2032, unless additional Congressional action is taken, and the Infrastructure Investment and Jobs Act, which added a requirement for manufacturers of certain single-source drugs (including biologics and biosimilars) separately paid for under Medicare Part B for at least 18 months and marketed in single-dose containers or packages (known as refundable single-dose containers or single-use package drugs) to provide annual refunds for any portions of the dispensed drug that are unused and discarded if those unused or discarded portions exceed an applicable percentage defined by statute or regulation.

Further, in November 2020, the U.S.

Department of Health and Human Services, or HHS, finalized a regulation removing safe harbor protection for price reductions from pharmaceutical manufacturers to plan sponsors under Part D, either directly or through pharmacy benefit managers, unless the price reduction is required by law.

Further, in November 2020, the HHS finalized a regulation removing safe harbor protection for price reductions from pharmaceutical manufacturers to plan sponsors under Part D, either directly or through pharmacy benefit managers, unless the price reduction is required by law.

The rule also creates a new safe harbor for price reductions reflected at the point-of-sale, as well as a safe harbor for certain fixed fee arrangements between pharmacy benefit managers and manufacturers.

The implementation of this final rule was delayed by the Inflation Reduction Act, or IRA, until January 1, 2032.

In December 2020, CMS issued a final rule implementing significant manufacturer price reporting changes under the Medicaid Drug Rebate Program, including regulations that affect manufacturer-sponsored patient assistance programs subject to pharmacy benefit manager accumulator programs and Best Price reporting related to certain value-based purchasing arrangements.

Under the American Rescue Plan Act of 2021, effective January 1, 2024, the statutory cap on Medicaid Drug Rebate Program rebates that manufacturers pay to state Medicaid programs is eliminated.

Elimination of this cap may require pharmaceutical manufacturers to pay more in rebates than they receive on the sale of products.

The implementation of this final rule was delayed by the IRA until January 1, 2032.

Under the American Rescue Plan Act of 2021, effective January 1, 2024, the statutory cap on Medicaid Drug Rebate Program rebates that manufacturers pay to state Medicaid programs has been eliminated.

Elimination of this cap has, in some instances, required pharmaceutical manufacturers to pay more in rebates than they have received on the sale of products.

Moreover, on January 2, 2013, the American Taxpayer Relief Act of 2012 was signed into law, which, among other things, further reduced Medicare payments to several types of providers, including hospitals, imaging centers and cancer treatment centers, and increased the statute of limitations period for the government to recover overpayments to providers from three to five years.

In November 2024, CMS issued a final rule, that decreased Medicare reimbursement for physician services by 2.8%, effective January 1, 2025.

If federal spending is further reduced, anticipated budgetary shortfalls may also impact the ability of relevant agencies, such as the FDA or the National Institutes of Health to continue to function at current levels.

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Moreover, payment methodologies, including payment for companion diagnostics, may be subject to changes in healthcare legislation and regulatory initiatives.

CMS has begun bundling the Medicare payments for certain laboratory tests ordered while a patient received services in a hospital outpatient setting and, beginning in 2018, CMS will pay for clinical laboratory services based on a weighted average of reported prices that private payors, Medicare Advantage plans, and Medicaid Managed Care plans pay for laboratory services.

Further, on March 16,

2018, CMS finalized its National Coverage Determination, or NCD, for certain diagnostic laboratory tests using next generation sequencing that are approved by the FDA as a companion in vitro diagnostic and used in a cancer with an FDA-approved companion diagnostic indication.

CMS bundles the Medicare payments for certain laboratory tests ordered while a patient received services in a hospital outpatient setting and CMS pays for clinical laboratory services based on a weighted average of reported prices that private payors, Medicare Advantage plans, and Medicaid Managed Care plans pay for laboratory services.

Further, on March 16, 2018, CMS finalized its National Coverage Determination, or NCD, for certain diagnostic laboratory tests using next generation sequencing that are approved by the FDA as a companion in vitro diagnostic and used in a cancer with an FDA-approved companion diagnostic indication.

Under the NCD, diagnostic tests that gain FDA approval or clearance as an in vitro companion diagnostic will automatically receive full coverage and be available for patients with recurrent, metastatic relapsed, refractory or stages III and IV cancer.

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There has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several presidential executive orders, Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products.

The FDA released a final rule in September 2020 providing guidance for states to build and submit importation plans for drugs from Canada, and the FDA authorized the first such plan in January 2024.

Recently, several healthcare reform initiatives culminated in the enactment of the IRA in August 2022, which allows, among other things, HHS to negotiate the selling price of a statutorily specified number of drugs and biologics each year that CMS reimburses under Medicare Part B and Part D.

Only high-expenditure single-source biologics that have been approved for at least 11 years (7 years for single-source drugs) can qualify for negotiations, with the negotiated price taking effect two years after the selection year.

Negotiations for Medicare Part D products begin in 2024 with the negotiated price taking effect in 2026, and negotiations for Medicare Part B products begin in 2026 with the negotiated price taking effect in 2028.

HHS will announce the negotiated maximum fair price by September 1, 2024, and this price cap, which cannot exceed a statutory ceiling price, will come into effect on January 1, 2026.

Additionally, several healthcare reform initiatives culminated in the enactment of the IRA in August 2022, which allows, among other things, HHS to directly negotiate the selling price of a statutorily specified number of drugs and biologics each year that CMS reimburses under Medicare Part B and Part D.

The negotiated price may not exceed a statutory ceiling price.

Only high-expenditure single-source biologics that have been approved for at least 11 years (7 years for single-source small molecule therapeutics) can qualify for negotiations, with the negotiated price taking effect two years after the selection year.

For 2026, the first year in which negotiated prices become effective, CMS selected 10 high-cost Medicare Part D products in 2023, negotiations began in 2024, and the negotiated maximum fair price for each product has been announced.

These negotiations resulted in significant price reductions for the products from their 2023 list prices, ranging from 38 to 79 percent, with an average price reduction of 59.4 percent.

CMS has selected 15 additional Medicare Part D drugs for negotiated maximum fair pricing in 2027.

For 2028, an additional 15 drugs, which may be covered under either Medicare Part B or Part D, will be selected, and for 2029 and subsequent years, 20 Part B or Part D drugs will be selected.

A drug or biological product that has an orphan drug designation for only one rare disease or condition will be excluded from the IRA’s price negotiations requirements, but loses that exclusion if it has designations for more than one rare disease or condition, or if it is approved for an indication that is not within that single designated rare disease or condition, unless such additional designation or such disqualifying approvals are withdrawn by the time CMS evaluates the drug for selection for negotiation.

In August 2023, HHS announced the ten Medicare Part D drugs and biologics that it selected for negotiations, and by October 1, 2023, each manufacturer of the selected drugs signed a manufacturer agreement to participate in the negotiations.

The IRA also penalizes drug manufacturers that increase prices of Medicare Part D and Part B drugs at a rate greater than the rate of inflation.

The IRA also imposes rebates on Medicare Part D and Part B drugs whose prices have increased at a rate greater than the rate of inflation, and in November 2024, CMS finalized regulations for the Medicare Part D and Part B inflation rebates.

In addition, the law eliminates the “donut hole” under Medicare Part D beginning in 2025 by significantly lowering the enrollee maximum out-of-pocket cost and requiring manufacturers to subsidize, through a newly established manufacturer discount program, 10% of Part D enrollees’ prescription costs for brand drugs below the out-of-pocket maximum, and 20% once the out-of-pocket maximum has been reached.

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The IRA also extends enhanced subsidies for individuals purchasing health insurance coverage in ACA marketplaces through plan year 2025.

These provisions are taking effect progressively starting in 2023, although they may be subject to legal challenges.

For example, the provisions related to the negotiation of selling prices of high-expenditure single-source drugs and biologics have been challenged in multiple lawsuits.

These provisions may be subject to legal challenges.

For example, the provisions related to the negotiation of selling prices of high-expenditure single-source drugs and biologics have been challenged in multiple lawsuits brought by pharmaceutical manufacturers.

Thus, while it is unclear how the IRA will be implemented, it will likely have a significant impact on the pharmaceutical industry and our product candidates.

At the state level, legislatures are increasingly enacting laws and implementing regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing.

For example, the FDA released a final rule in September 2020 providing guidance for states to build and submit importation plans for drugs from Canada, and the FDA authorized the first such plan in January 2024, which has been extended until July 2025.

It is unclear how this program will be implemented, including which drugs will be chosen, and whether it will be subject to legal challenges in the United States or Canada.

Other states have also submitted proposals that are pending review by the FDA.

Additionally, on May 30, 2018, the Trickett Wendler, Frank Mongiello, Jordan McLinn, and Matthew Bellina Right to Try Act of 2017 was signed into law.

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Moreover, the government may assert that a claim including items and services resulting from a violation of the federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the federal False Claims Act;

• HIPAA, which imposes criminal and civil liability, prohibits, among other things, knowingly and willfully executing, or attempting to execute a scheme to defraud any healthcare benefit program, or knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services;

• the Health Insurance Portability and Accountability Act, or HIPAA, which imposes criminal and civil liability, prohibits, among other things, knowingly and willfully executing, or attempting to execute a scheme to defraud any healthcare benefit program, or knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services;

similar to the federal Anti-Kickback Statute, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation;

• HIPAA, as amended by HITECH, which impose obligations on certain healthcare providers, health plans, and healthcare clearinghouses, known as covered entities, as well as their business associates that perform certain services involving the storage, use or disclosure of individually identifiable health information, including mandatory contractual terms, with respect to safeguarding the privacy, security, and transmission of individually identifiable health information, and require notification to affected individuals and regulatory authorities of certain breaches of security of individually identifiable health information;

• the federal legislation commonly referred to as Physician Payments Sunshine Act, enacted as part of the ACA, and its implementing regulations, which requires certain manufacturers of covered drugs, devices, biologics and medical supplies that are reimbursable under Medicare, Medicaid, or the Children’s Health Insurance Program, with certain exceptions, to report annually to CMS information related to certain payments and other transfers of value to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), physician assistants, certain types of advanced practice nurses, and

teaching hospitals, as well as ownership and investment interests held by the physicians described above and their immediate family members, with the information made publicly available on a searchable website;

• HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, or HITECH, which impose obligations on certain healthcare providers, health plans, and healthcare clearinghouses, known as covered entities, as well as their business associates that perform certain

services involving the storage, use or disclosure of individually identifiable health information, including mandatory contractual terms, with respect to safeguarding the privacy, security, and transmission of individually identifiable health information, and require notification to affected individuals and regulatory authorities of certain breaches of security of individually identifiable health information;

Foreign Corrupt Practices Act of 1977, as amended, which prohibits, among other things, U.S.

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Although effective compliance programs can mitigate the risk of investigation and prosecution for violations of these laws, these risks cannot be entirely eliminated.

Any action against us for an alleged or suspected violation could cause us to incur significant legal expenses and could divert our management’s attention from the operation of our business, even if our defense is successful.

Any action against us for an alleged or suspected violation could cause us to incur significant legal expenses and could divert our

management’s attention from the operation of our business, even if our defense is successful.

In addition, achieving and sustaining compliance with applicable laws and regulations may be costly to us in terms of money, time and resources.

Our failure to comply with privacy and data security laws, regulations and standards may cause our business to be materially adversely affected.

We maintain a quantity of sensitive information, including confidential business and patient health information in connection with our clinical trials that are subject to US and international laws and regulations governing the privacy and data protection of such information.

We maintain a quantity of sensitive and confidential information, including confidential business and patient health information in connection with our clinical trials that are subject to US and international laws and regulations governing the privacy and data protection of such information.

Each of these laws is subject to varying interpretations and subject to evolving regulations.

For example, the EU and United Kingdom (“UK”) GDPR, which applies

extraterritorially, imposes several strict requirements for controllers and processors of personal information, which include higher standards for obtaining consent from individuals to process their personal information, increased requirements pertaining to the processing of special categories of personal information (such as health information) and pseudonymized (i.e., key-coded) data, and heightened transfer requirements of personal information from the European Economic Area/UK/Switzerland to countries not deemed to have adequate data protections laws.

Notably, the U.S.

is one such country as of January 1, 2024, although effective July 10, 2023, the new EU-U.S.

Data Privacy Framework (“DPF”) has been recognized as adequate under EU law to allow transfers of personal data from the EU (as well as the U.K.

and Switzerland) to certified companies in the U.S.

However, the DPF is likely to face legal challenge at the Court of Justice of the European Union which could cause the legal requirements for personal data transfers from the Europe to the U.S.

to become uncertain once again.

We will monitor these legal developments and continue to use best practices to follow established European legal standards to conduct cross-border transfer of personal data.

The GDPR also provides that countries in the European Economic Area may establish their own laws and regulations further restricting the processing of certain personal information, including genetic data, biometric data, and health data.

Companies that must comply with the GDPR face increased compliance obligations and risk, including more robust regulatory enforcement of data protection requirements and potential fines for noncompliance of up to €20 million (approximately $22.6 million) or 4 percent of the annual global revenues of the noncompliant company, whichever is greater.

For example, the EU and United Kingdom, UK respective General Data Protection Regulations, or GDPR, which apply extraterritorially, impose strict requirements for controllers and processors of personal information, which include high standards for obtaining consent from individuals to process their personal information, increased requirements pertaining to the processing of special categories of personal information (such as health information), including in pseudonymized (i.e., key-coded) form, and heightened transfer requirements of personal information from the European Economic Area/UK/Switzerland to countries not deemed to have adequate data protections laws (including the U.S.).

Companies that must comply with the GDPR face increased compliance obligations and risk, including more robust regulatory enforcement of data protection requirements and potential fines for noncompliance of up to €20 million (£17.5 million in the UK) or 4 percent of the annual global revenues of the noncompliant company, whichever is greater.

In the United States, in addition to HIPAA, various federal (for example, the Federal Trade Commission) and state regulators have adopted, or are considering adopting, laws and regulations concerning personal information and data security that may conflict or be more stringent or broader in scope, or offer greater individual rights, with respect to personal information than existing federal, international, or other state laws.

For example, California, which continues to be a critical state with respect to evolving consumer privacy laws after enacting the California Consumer Privacy Act (the “CCPA”), as amended by the California Privacy Rights Act, took effect in January 2023 and may be subject to additional regulations promulgated through a newly created enforcement agency called the California Privacy Protection Agency (“CPPA”).

Failure to comply with the CCPA may result in significant civil penalties, injunctive relief, or statutory or actual damages as determined by the CPPA and California Attorney General, the latter still retaining some CCPA enforcement authority.

Following California’s lead, several other state enacted privacy laws that took effect in 2023:

the Colorado Privacy Act, the Connecticut Personal Data Privacy and Online Monitoring Act, the Utah Consumer Privacy Act, and the Virginia Consumer Data Protection Act.

Additional state privacy laws are to take effect in 2024:

the Florida Digital Bill of Rights (July 1, 2024), Montana’s Consumer Data Privacy Act (October 1, 2024), Oregon’s protections for the personal data of consumers enacted through SB 619 (July 1, 2024), and the Texas Data Privacy and Security Act (July 1, 2024).

For example, California enacted the California Consumer Privacy Act, or as amended, the CCPA which grants individual privacy rights for California consumers and places increased privacy and data security obligations on entities handling personal information of consumers or households.

Failure to comply with the CCPA may result in significant civil penalties, injunctive relief, or statutory or actual damages.

Following California’s lead, over a third of U.S.

states have adopted comprehensive privacy and security laws and regulations, which govern the privacy, processing and protection of personal information, including certain specific requirements and laws with respect to health-related information.

For example, Washington state has passed the My Health My Data Act, which is focused on the collection of consumer health data, has a broader scope than HIPAA and includes a private right of action .

In addition, various comprehensive federal privacy bills have been proposed in Congress.

We cannot provide assurance that (i) current or future legislation will not prevent us from generating or maintaining personal information, or (ii) that patients will consent to the use of their personal information (as necessary).

Either of these circumstances may prevent us from undertaking or publishing essential research and development, manufacturing, and commercialization, which could have a material adverse effect on our business, results of operations, financial condition, and prospects.

Further, on July 26, 2023, the SEC adopted new cybersecurity disclosure rules for public companies that require disclosure regarding cybersecurity risk management (including our board’s role in overseeing cybersecurity risks, management’s role and expertise in assessing and managing cybersecurity risks and processes for assessing, identifying and managing cybersecurity risks) in annual reports on Form 10-K.

These new cybersecurity disclosure rules also require the disclosure of material cybersecurity incidents by Form 8-K.

In addition to government regulation, privacy advocates and industry groups have and may in the future propose self-regulatory standards from time to time.

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All of these evolving compliance and operational requirements impose significant costs, such as costs related to organizational changes, implementing additional protection technologies, training employees and engaging consultants, which are likely to increase over time.

In addition, such requirements may require us to modify our

data processing practices and policies, distract management or divert resources from other initiatives and projects, all of which could have a material adverse effect on our business, financial condition, results of operations and prospects.

Any failure or perceived failure by us to comply with any applicable federal, state, or similar foreign laws and regulations relating to data privacy and security could result in damage to our reputation, as well as proceedings or litigation by governmental agencies or other third parties, including class action privacy litigation in certain jurisdictions, which would subject us to significant fines, sanctions, awards, injunctions, penalties, or judgments.

In addition, such requirements may require us to modify our data processing practices and policies, distract management or divert resources from other initiatives and projects, all of which could have a material adverse effect on our business, financial condition, results of operations and prospects.

litigation in certain jurisdictions, which would subject us to significant fines, sanctions, awards, injunctions, penalties, or judgments.

Any of the foregoing could have a material adverse effect on our business, results of operations, financial condition, and prospects.

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To commercialize any product candidates after approval, we must build, on a territory-by-territory basis, marketing, sales, distribution, managerial and other non-technical capabilities or make arrangements with third parties to perform these services, and we may not be successful in doing so.

If our product candidates receive regulatory approval, we may decide to establish an internal sales or marketing team with technical expertise and supporting distribution capabilities to commercialize our product candidates, which will be expensive and time consuming and will require significant attention of our executive officers to manage.

If our product candidates receive regulatory approval, we may decide to establish a sales or marketing team with technical expertise and supporting distribution capabilities to commercialize our product candidates, which will be expensive and time consuming and will require significant attention of our executive officers to manage.

For example, some state and local jurisdictions have licensing and continuing education requirements for pharmaceutical sales representatives, which requires time and financial resources.

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Our product candidates for which we intend to seek approval as biologic products may face competition sooner than anticipated.

With the enactment of the Biologics Price Competition and Innovation Act of 2009, or BPCIA, an abbreviated pathway for the licensure of biosimilar biological products (both highly similar and interchangeable biological products) was created.

The abbreviated regulatory pathway establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as interchangeable based on its similarity to an existing reference product.

The BPCIA provides a period of exclusivity for products granted “reference product exclusivity,” under which an application for a biosimilar product referencing such products cannot be licensed by the FDA until 12 years after the first licensure date of the reference product licensed under a BLA.

With the enactment of the Biologics Price Competition and Innovation Act of 2009, or BPCIA, an abbreviated pathway for the licensure of highly similar and interchangeable biosimilar products was created.

The abbreviated regulatory pathway establishes legal authority for the FDA to review and approve a biosimilar biologic, including the possible designation of a biosimilar as interchangeable, based on its similarity to an existing reference product.

The BPCIA provides a period of reference product exclusivity for biological products during which an application for a biosimilar product referencing such products cannot be licensed by the FDA until 12 years after the first licensure date of the reference product.

Additionally, a biosimilar application referencing such exclusivity-protected biological products may not be submitted for four years after the first licensure date of the reference product.

During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA licenses a full BLA for the competing product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product.

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As a result, its ultimate impact, implementation, and meaning are subject to uncertainty.

While it is uncertain when such processes intended to implement BPCIA may be fully adopted by the FDA, any such processes could have an adverse effect on the future commercial prospects for our product candidates.

There is a risk that any product candidates we may develop that are licensed as a biological product under a BLA would not qualify for the 12-year period of exclusivity or that this exclusivity could be shortened due to congressional action or otherwise, or that the FDA will not consider any product candidates we may develop to be

reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated.

While it is uncertain when and how such processes intended to implement BPCIA may be fully adopted by the FDA, any such processes could have an adverse effect on the future commercial prospects for our product candidates.

There is a risk that any product candidates we may develop that are licensed as a biological product under a BLA would not qualify for the 12-year period of exclusivity or that this exclusivity could be shortened due to congressional action or otherwise, potentially creating the opportunity for generic competition sooner than anticipated.

Most states have enacted substitution laws that permit substitution of interchangeable biosimilars.

The extent to which a highly similar biosimilar, once licensed, will be substituted for any one of our reference products that may be approved in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

The extent to which a biosimilar, once licensed, will be substituted for any one of our reference products that may be

approved is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

If any of our product candidates receives marketing approval and we or others later identify undesirable side effects caused by the product candidates, our ability to market and derive revenue from the product candidates could be compromised.

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Further, clinical trials by their nature utilize a sample of the potential patient population.

With a limited number of patients and limited duration of exposure, rare and

With a limited number of patients and limited duration of exposure, rare and severe side effects of our product candidates may only be uncovered with a significantly larger number of patients exposed to the product candidate.

In the event that any of our product candidates receive regulatory approval and we or others identify undesirable side effects caused by one of our products, any of the following adverse events could occur:

• regulatory authorities may withdraw their approval of the product or seize the product;

• we may be required to recall the product or change the way the product is administered to patients;

• additional restrictions may be imposed on the marketing of the particular product or the manufacturing processes for the product or any component thereof;

• we may be subject to fines, injunctions or the imposition of civil or criminal penalties;

• regulatory authorities may require the addition of labeling statements, such as a boxed warning or a contraindication;

• we may be required to create a medication guide outlining the risks of such side effects for distribution to patients;

• we could be sued and held liable for harm caused to patients;

• the product may become less competitive;

• our reputation may suffer.

Any of these occurrences could have a material and adverse effect on our business, financial condition, results of operations and prospects.

If we decide to seek Fast Track Designation by the FDA for any product candidate, even if successful, it may not lead to a faster development or regulatory review or approval process.

As part of our business strategy, we may seek Fast Track Designation for our product candidates.

If a drug or biologic is intended for the treatment of a serious or life-threatening condition and the drug or biologic demonstrates the potential to address unmet medical needs for this condition, the product sponsor may apply for FDA Fast Track Designation.

The FDA has broad discretion whether or not to grant this designation, so even if we believe a particular product candidate is eligible for this designation, we cannot assure you that the FDA would

decide to grant it.

Even if we do receive Fast Track Designation, we may not experience a faster development process, review or approval compared to conventional FDA procedures.

The FDA may withdraw Fast Track Designation if it believes that the designation is no longer supported by data from our clinical development program, which may happen in connection with any product candidates if granted Fast Track Designation.

If we decide to seek Orphan Drug Designation for some of our product candidates, we may be unsuccessful or may be unable to maintain the benefits associated with Orphan Drug Designation, including the potential for orphan drug exclusivity.

As part of our business strategy, we may seek Orphan Drug Designation for our product candidates, and we may be unsuccessful.

Regulatory authorities in some jurisdictions, including the United States and Europe, may designate drugs and therapeutic biologics for relatively small patient populations as orphan drugs.

Under the Orphan Drug Act, the FDA may designate a drug or therapeutic biologic as an orphan drug if it is a drug or therapeutic biologic intended to treat a rare disease or condition, which is defined as a patient population of fewer than 200,000 individuals in the United States, or a patient population greater than 200,000 in the United States where there is no reasonable expectation that the cost of developing the drug or therapeutic biologic will be recovered from sales in the United States.

In the United States, Orphan Drug Designation entitles a party to financial incentives such as tax advantages and user fee waivers.

In addition, if a product that has Orphan Drug Designation subsequently receives the first FDA approval of the drug to treat the disease for which it has such designation, the product is entitled to orphan drug exclusivity, which means that the FDA may not approve any other applications, including a full BLA, to market the same product for the same condition for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity or where the manufacturer is unable to assure sufficient product quantity.

Even if we obtain Orphan Drug Designation for our product candidates in specific conditions, we may not be the first to obtain marketing approval of these product candidates for the orphan-designated condition due to the uncertainties associated with developing pharmaceutical products;

in such case, no orphan drug exclusivity would be available unless we could demonstrate “clinical superiority.” In addition, exclusive marketing rights in the United States may be limited if we seek approval for an indication broader than the orphan-designated condition or may be lost if the FDA later determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantities of the product to meet the needs of patients with the rare disease or condition.

Further, even if we obtain orphan drug exclusivity for a product, that exclusivity may not effectively protect the product from competition because different drugs or therapeutic biologics with different principal molecular structural features can be approved for the same condition.

Even after an orphan product is approved, the FDA can subsequently approve the same drug or therapeutic biologic with the same principal molecular structural features for the same condition if the FDA concludes that the later drug or therapeutic biologic is safer, more effective or makes a major contribution to patient care.

Orphan Drug Designation neither shortens the development time or regulatory review time of a drug or therapeutic biologic nor gives the drug or therapeutic biologic any advantage in the regulatory review or approval process.

In addition, while we may seek Orphan Drug Designation for our product candidates, we may not receive such designations.

The tax reform legislation signed into law on December 22, 2017 reduced the amount of the qualified clinical research costs for a designated orphan product that a sponsor may claim as a credit from 50% to 25%.

This may further limit the advantage and may impact our future business strategy of seeking the Orphan Drug Designation.

If we decide to pursue accelerated approval for any of our product candidates, it may not lead to a faster development or regulatory review or approval process and does not increase the likelihood that our product candidates will receive marketing approval.

In the future, we may decide to pursue accelerated approval for one or more of our product candidates.

Under the FDA’s accelerated approval program, the FDA may approve a drug or biologic for a serious or life-threatening disease or condition that provides a meaningful advantage over available therapies based upon a surrogate endpoint that is reasonably likely to predict clinical benefit, or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality that is reasonably likely to predict an effect on irreversible morbidity or mortality or other clinical benefit.

For drugs or biologics granted accelerated approval, post-marketing confirmatory trials are required to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefit.

These confirmatory trials must be completed with due diligence, and the FDA may require that the trial be designed, initiated, and/or fully enrolled prior to approval.

If we were to pursue accelerated

approval for a product candidate for a disease or condition, we would do so on the basis that there is no available therapy for that disease or condition or that our product candidate provides a benefit over available therapy.

If standard of care were to evolve or if any of our competitors were to receive full approval on the basis of a confirmatory trial for a drug or biologic for a disease or condition for which we are seeking accelerated approval before we receive accelerated approval, the disease or condition would no longer qualify as one for which there is no available therapy, and accelerated approval of our product candidate would not occur without a showing of benefit over available therapy.

Many cancer therapies rely on accelerated approval, and the treatment landscape can change quickly as the FDA converts accelerated approvals to full approvals on the basis of successful confirmatory trials.

Whether any trial is sufficient to receive FDA approval under the accelerated approval pathway will depend on the design and safety and efficacy results of such trial and will only be determined by the FDA upon review of the trial design and a submitted BLA.

Moreover, the FDA may withdraw approval of any product candidate approved under the accelerated approval pathway if, for example:

• the trial or trials required to verify the predicted clinical benefit of our product candidate fail to verify such benefit or do not demonstrate sufficient clinical benefit to justify the risks associated with such product;

• other evidence demonstrates that our product candidate is not shown to be safe or effective under the conditions of use;

• we fail to conduct any required post-approval trial of our product candidate with due diligence;

• we disseminate false or misleading promotional materials relating to the relevant product candidate.

In addition, the FDA may terminate the accelerated approval program or change the standards under which accelerated approvals are considered and granted in response to public pressure or other concerns regarding the accelerated approval program.

Changes to or termination of the accelerated approval program could prevent or limit our ability to obtain accelerated approval of any of our clinical development programs.

Recently, the accelerated approval pathway has come under scrutiny within the FDA and by Congress.

The FDA has put increased focus on ensuring that confirmatory studies are conducted with diligence and, ultimately, that such studies confirm the benefit.

For example, the FDA has convened its Oncologic Drugs Advisory Committee to review what the FDA has called “dangling” or delinquent accelerated approvals, where confirmatory studies have not been completed or where results did not confirm benefit, but for which marketing approval continues in effect, and some companies have subsequently voluntarily requested withdrawal of approval of their products.

In addition, the Oncology Center of Excellence has announced Project Confirm, which is an initiative to promote the transparency of outcomes related to accelerated approvals for oncology indications and provide a framework to foster discussion, research and innovation in approval and post-marketing processes, with the goal to enhance the balance of access and verification of benefit for therapies available to patients with cancer and hematologic malignancies.

Further, the enactment of The Food and Drug Omnibus Reform Act, or FDORA, included provisions related to the accelerated approval pathway.

Pursuant to FDORA, the FDA is authorized to require a post-approval study to be underway prior to approval or within a specified time period following approval.

FDORA also requires the FDA to specify conditions of any required post-approval study and requires sponsors to submit progress reports for required post-approval studies and any conditions required by the FDA.

FDORA enables the FDA to initiate enforcement action for the failure to conduct with due diligence a required post-approval study, including a failure to meet any required conditions specified by the FDA or to submit timely reports.

There is substantial uncertainty regarding the new Administration’s initiatives and how these might impact the FDA, its implementation of laws, regulations, policies and guidance and its personnel.

These initiatives could prevent, limit or delay development and regulatory approval, and/or impact commercialization, of our product candidates, which would impact our ability to generate revenue.

FDA-regulated industries, such as ours, face substantial uncertainty regarding the regulatory environment we will face as we proceed with research and development, and possibly in future commercialization, efforts following

the inauguration of President Trump in January 2025 (the “Administration”).

Some of these efforts have manifested to date in the form of personnel measures that could impact the FDA’s ability to hire and retain key personnel, which could result in delays in or limitations on our ability to obtain guidance from the FDA on our product candidates in development and obtaining the requisite regulatory approvals in the future.

There remains general uncertainty regarding future activities.

The new Administration could issue or promulgate executive orders, regulations, policies or guidance that adversely affect us or create a more challenging or costly environment to pursue the development and sale of new therapeutic products.

For example, on January 20, 2025, President Trump announced an executive order establishing the Department of Government Efficiency to maximize government efficiency and productivity.

Pressures on and uncertainty surrounding the U.S.

federal government’s budget and potential changes in budgetary priorities could adversely affect the funding for existing programs and grants and increase the costs to us of conducting clinical trials.

Alternatively, state governments may attempt to address or react to changes at the federal level with changes to their own regulatory frameworks in a manner that is adverse to our operations.

If we or our collaborators become negatively impacted by future governmental orders, regulations, policies or guidance as a result of the new Administration, there could be a material adverse effect on us and our operating results.

Risks Related to Our Common Stock

Our quarterly and annual operating results may fluctuate significantly or may fall below the expectations of investors or securities analysts, each of which may cause our stock price to fluctuate or decline.

We expect our operating results to be subject to quarterly and annual fluctuations.

Our net income or loss and other operating results will be affected by numerous factors, including:

• variations in the level of expense related to the ongoing development of our XpressCF ® and XpressCF+ ® platforms, our product candidates or future development programs;

• results of preclinical and clinical trials, or the addition or termination of clinical trials or funding support by us, or existing or future collaborators or licensing partners;

• our execution of any additional collaboration, licensing or similar arrangements, and the timing of payments we may make or receive under existing or future arrangements or the termination or modification of any such existing or future arrangements;

• any intellectual property infringement lawsuit or opposition, interference or cancellation proceeding in which we may become involved;

• additions and departures of key personnel;

• strategic decisions by us or our competitors, such as acquisitions, divestitures, spin-offs, joint ventures, strategic investments or changes in business strategy;

• if any of our product candidates receives regulatory approval, the terms of such approval and market acceptance and demand for such product candidates;

• regulatory developments affecting our product candidates or those of our competitors;

• the impact of accounting principles and tax laws, including as a result of recent tax law changes;

• epidemics, pandemics or contagious diseases;

• changes in general market and economic conditions;

• cybersecurity incidents

If our quarterly and annual operating results fall below the expectations of investors or securities analysts, the price of our common stock could decline substantially.

Furthermore, any quarterly and annual fluctuations in our operating results may, in turn, cause the price of our common stock to fluctuate substantially.

We believe that quarterly and annual comparisons of our financial results are not necessarily meaningful and should not be relied upon as an indication of our future performance.

Anti-takeover provisions in our charter documents and under Delaware law could make an acquisition of us, which may be beneficial to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

Our restated certificate of incorporation and our restated bylaws contain provisions that could delay or prevent a change in control of our company.

These provisions could also make it difficult for stockholders to elect directors who are not nominated by current members of our board of directors or take other corporate actions, including effecting changes in our management.

These provisions:

• establish a classified board of directors so that not all members of our board are elected at one time;

• permit only the board of directors to establish the number of directors and fill vacancies on the board;

• provide that directors may only be removed “for cause” and only with the approval of two-thirds of our stockholders;

• require super-majority voting to amend some provisions in our restated certificate of incorporation and restated bylaws;

• authorize the issuance of “blank check” preferred stock that our board could use to implement a stockholder rights plan;

• eliminate the ability of our stockholders to call special meetings of stockholders;

• prohibit stockholder action by written consent, which requires all stockholder actions to be taken at a meeting of our stockholders;

• prohibit cumulative voting;

• establish advance notice requirements for nominations for election to our board or for proposing matters that can be acted upon by stockholders at annual stockholder meetings.

In addition, our restated certificate of incorporation, to the fullest extent permitted by law, provides that the Court of Chancery of the State of Delaware is the exclusive forum for:

any derivative action or proceeding brought on our behalf;

any action asserting a breach of fiduciary duty;

any action asserting a claim against us arising pursuant to the Delaware General Corporation Law, or DGCL, our restated certificate of incorporation, or our restated bylaws;

or any action asserting a claim against us that is governed by the internal affairs doctrine.

Furthermore, our amended and restated bylaws also provide that unless we consent in writing to the selection of an alternative forum, the federal district courts of the United States shall be the exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act, or Federal Forum Provision.

While the Supreme Court of the State of Delaware has held that such provisions are facially valid under Delaware law, there can be no assurance that federal or state courts will follow the holding of the Delaware Supreme Court or determine that the Federal Forum Provision should be enforced in a particular case;

application of the Federal Forum Provision means that suits brought by our stockholders to enforce any duty or liability created by the Securities Act of 1933, as amended, or Securities Act, must be brought in federal court and cannot be brought in state court.

These choice of forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or any of our directors, officers, or other employees, which may discourage lawsuits against us and our directors, officers, employees and agents even though an action, if successful, might benefit our stockholders.

Stockholders who do bring a claim in the specified courts could face additional litigation

costs in pursuing any such claim.

The specified courts may also reach different judgments or results than would other courts, including courts where a stockholder considering an action may be located or would otherwise choose to bring the action, and such judgments or results may be more favorable to us than to our stockholders.

Alternatively, if a court were to find these provisions of our governance documents inapplicable to, or unenforceable in respect of, one or more of the specified types of actions or proceedings, we may incur additional costs associated with resolving such matters in other jurisdictions, which could have a material adverse effect on our business, financial condition, results of operations and prospects.

In addition, Section 203 of the DGCL may discourage, delay or prevent a change in control of our company.

Section 203 imposes certain restrictions on mergers, business combinations and other transactions between us and holders of 15% or more of our common stock.

The exclusive forum provision in our organizational documents may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or any of our directors, officers or other employees, or the underwriters of any offering giving rise to such claim, which may discourage lawsuits with respect to such claims.

Our amended and restated certificate of incorporation provides that, to the fullest extent permitted by law, the Court of Chancery of the State of Delaware is the exclusive forum for:

any derivative action or proceeding brought on our behalf;

any action asserting a breach of fiduciary duty;

any action asserting a claim against us arising pursuant to the DGCL, our amended and restated certificate of incorporation or our amended and restated bylaws;

or any action asserting a claim against us that is governed by the internal affairs doctrine.

This exclusive forum provision does not apply to suits brought to enforce a duty or liability created by the Securities Exchange Act of 1934, as amended, or Exchange Act.

It could apply, however, to a suit that falls within one or more of the categories enumerated in the exclusive forum provision.

This choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or any of our directors, officers, or other employees, or the underwriters of any offering giving rise to such claims, which may discourage lawsuits with respect to such claims.

Alternatively, if a court were to find the choice of forum provisions contained in our amended and restated certificate of incorporation to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could harm our business, results of operations and financial condition.

Section 22 of the Securities Act, creates concurrent jurisdiction for federal and state courts over all claims brought to enforce any duty or liability created by the Securities Act or the rules and regulations thereunder.

Our amended and restated bylaws provide that the federal district courts of the United States of America will, to the fullest extent permitted by law, be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act, or a Federal Forum Provision, including for all causes of action asserted against any defendant named in such complaint.

For the avoidance of doubt, this provision is intended to benefit and may be enforced by us, our officers and directors, the underwriters to any offering giving rise to such complaint and any other professional entity whose profession gives authority to a statement made by that person or entity and who has prepared or certified any part of the documents underlying the offering.

Our decision to adopt a Federal Forum Provision followed a decision by the Supreme Court of the State of Delaware holding that such provisions are facially valid under Delaware law.

While federal or state courts may not follow the holding of the Delaware Supreme Court or may determine that the Federal Forum Provision should be enforced in a particular case, application of the Federal Forum Provision means that suits brought by our stockholders to enforce any duty or liability created by the Securities Act must be brought in federal court and cannot be brought in state court, and our stockholders cannot waive compliance with the federal securities laws and the rules and regulations thereunder.

Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, capital appreciation, if any, will be your sole source of gain.

We have never declared or paid cash dividends on our capital stock.

We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business.

As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future.

The market price of our stock may be volatile, and you could lose all or part of your investment.

The trading price of our common stock may be highly volatile and subject to wide fluctuations in response to various factors, some of which we cannot control.

As a result of this volatility, investors may not be able to sell their common stock at or above the purchase price.

The market price for our common stock may be influenced by many factors, including the other risks described in this section and the following:

• results of preclinical studies and clinical trials of our product candidates, or those of our competitors or our existing or future collaborators;

• regulatory or legal developments in the United States and other countries, especially changes in laws or regulations applicable to our product candidates;

• the success of competitive products or technologies;

• introductions and announcements of new products by us, our future commercialization partners, or our competitors, and the timing of these introductions or announcements;

• actions taken by regulatory agencies with respect to our products, clinical studies, manufacturing process or sales and marketing terms;

• actual or anticipated variations in our financial results or those of companies that are perceived to be similar to us;

• the success of our efforts to acquire or in-license additional technologies, products or product candidates;

• developments concerning current or future collaborations, including but not limited to those with our sources of manufacturing supply and our commercialization partners;

• market conditions in the pharmaceutical and biotechnology sectors;

• general economic uncertainty and capital markets disruptions, including changes in interest rates, a new U.S.

presidential administration, rising inflation, changes in tariffs and trade restrictions, potential instability, which have been substantially impacted by regional geopolitical instability due to the impact of geopolitical tensions and the ongoing military conflicts around the world;

• any adverse impact of health pandemics, including on our clinical trials and clinical trial operations;

• announcements by us or our competitors of significant acquisitions, strategic collaborations, joint ventures or capital commitments;

• developments or disputes concerning patents or other proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our product candidates and products;

• our ability or inability to raise additional capital and the terms on which we raise it;

• the recruitment or departure of key personnel;

• changes in the structure of healthcare payment systems;

• actual or anticipated changes in earnings estimates or changes in stock market analyst recommendations regarding our common stock, other comparable companies or our industry generally;

• our failure or the failure of our competitors to meet analysts’ projections or guidance that we or our competitors may give to the market;

• fluctuations in the valuation of companies perceived by investors to be comparable to us;

• announcement and expectation of additional financing efforts;

• speculation in the press or investment community;

• trading volume of our common stock;

• sales of our common stock by us or our stockholders;

• changes in accounting principles or tax laws;

• terrorist acts, acts of war or periods of widespread civil unrest, including the ongoing armed conflicts around the world;

• natural disasters, epidemics, pandemics or contagious diseases, and other calamities;

• political instability;

• general economic, industry and market conditions.

In addition, the stock market in general, and the markets for pharmaceutical, biopharmaceutical and biotechnology stocks in particular, have experienced extreme price and volume fluctuations that have been often unrelated or disproportionate to the operating performance of the issuer.

These broad market and industry factors may seriously harm the market price of our common stock, regardless of our actual operating performance.

The realization of any of the above risks or any of a broad range of other risks, including those described in this “Risk Factors” section, could have a dramatic and adverse impact on the market price of our common stock.

The future sale and issuance of equity or of debt securities that are convertible into equity will dilute our share capital.

We may choose to raise additional capital in the future, depending on market conditions, strategic considerations and operational requirements.

To the extent that additional capital is raised through the sale and issuance of shares or other securities convertible into shares, our stockholders will be diluted.

Future issuances of our common stock or other equity securities, or the perception that such sales may occur, could adversely affect the trading price of our common stock and impair our ability to raise capital through future offerings of shares or equity securities.

No prediction can be made as to the effect, if any, that future sales of common stock or the availability of common stock for future sales will have on the trading price of our common stock.

A sale of a substantial number of shares of our common stock may cause the price of our common stock to decline.

Sales of a substantial number of shares of our common stock in the public market could occur at any time.

If our stockholders sell, or the market perceives that our stockholders intend to sell, substantial amounts of our common stock in the public market, the market price of our common stock could decline significantly.

We cannot predict what effect, if any, sales of our shares in the public market or the availability of shares for sale will have on the market price of our common stock.

However, future sales of substantial amounts of our common stock in the public market, including shares issued upon exercise of outstanding options or warrants, or the perception that such sales may occur, could adversely affect the market price of our common stock.

For example, we are party to a Sales Agreement with Jefferies, pursuant to which, from time to time, we may offer and sell through Jefferies common stock pursuant to one or more “at the market” offerings.

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 1. Business