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Item 1. Business

2026-02-25 compared with 2025-02-27 · 376 added, 402 removed, 328 unchanged (70% of the section changed)

We are a clinical-stage biopharmaceutical company focused on discovering and developing engineered antibody therapeutics to treat patients with cancer and autoimmune diseases, who have unmet medical needs.

We use our protein engineering capabilities to design new technologies and XmAb® drug candidates with improved properties.

We advance these candidates into clinical-stage development, where we are conducting Phase 1 and Phase 2 studies for a broad portfolio of programs, to determine which programs we advance into later stages of development and potentially commercialization, which programs we partner to access complementary resources to optimize development, and which programs we discontinue.

We use our protein engineering capabilities to design new technologies and XmAb ® drug candidates with improved properties and multi-target mechanisms of action.

We advance these candidates into clinical-stage development, where we are conducting Phase 1 and Phase 2 studies for a broad portfolio of programs, to determine which programs to advance into later stages of development and potentially commercialization, which programs we partner to optimize development, and which programs we discontinue.

Our approach to protein design includes engineering Fc domains, the parts of antibodies that interact with multiple segments of the immune system and control antibody structure.

The Fc domain is constant and interchangeable among antibodies, and our engineered XmAb Fc domains can be readily substituted for natural Fc domains.

The Fc domain is constant and interchangeable across antibodies, and our engineered Fc domains can be readily substituted for natural Fc domains.

These Fc domains provide specific features such as bispecific structure and extended half-life and serve as the scaffolds for our XmAb drug candidates.

We and our partners develop XmAb antibodies and other types of biotherapeutic drug candidates with improved properties and functionality, which can provide innovative approaches to potentially treating disease and clinical benefits over other treatment options.

Applications of our protein engineering technologies include multi-specific antibodies that bind two or more different targets simultaneously, creating entirely new biological mechanism of anti-disease activity, or enhancement of antibody performance by increasing immune inhibitory activity, improving cytotoxicity, extending circulating half-life and stabilizing novel protein structures.

Three marketed XmAb medicines have been developed with our protein engineering technologies.

Our protein engineering capabilities allow us to continually explore new functionality in the Fc region, which provides us with opportunities to:

• Engineer new drug candidates and advance them through clinical development;

• Create new technology platforms;

• Provide collaboration and licensing opportunities with partners for application of our technologies, access to our technologies, access to our drug candidates, or combinations of each.

Our goal is to become a leading biopharmaceutical company that develops and commercializes engineered biologic medicines to treat patients with severe and life-threatening diseases with unmet medical needs.

Key elements of our strategy are to:

Advance the development of our XmAb antibody programs for oncology and autoimmune diseases.

Our modular bispecific technology and protein engineering capabilities enable us to rapidly advance multiple drug candidates into clinical development.

We and our partners are enrolling patients in multiple clinical studies to evaluate XmAb drug candidates.

Build and manage a pipeline of XmAb drug candidates.

We advance multiple XmAb drug candidates into early stages of clinical development and evaluate data from studies in managing our pipeline of candidates.

Based on the evaluation of emerging data and the competitive environment for such programs, we make additional investments in those candidates that demonstrate encouraging proof of concept, partner certain drug candidates to third-party biotechnology and pharmaceutical companies, and stop development of some candidates due to emerging data and resource allocation across our pipeline.

Leverage our protein engineering capabilities, XmAb Fc domains, and XmAb drug candidates with partnerships, collaborations, and licenses to generate revenue streams, create new drug candidates and combination treatments, and identify new indications for our pipeline of drug candidates.

Generate revenue streams.

The plug-and-play nature of our Fc technologies and our ability to generate multiple drug candidates efficiently provides us opportunities to generate revenue from licensing and collaboration arrangements.

Create new XmAb drug candidates and investigate novel combination therapies .

We seek to leverage our XmAb Fc domains and protein engineering capabilities with partners to create novel XmAb drug candidates, and to evaluate our XmAb drug candidates in combination with other therapeutic agents, when applicable.

Identify new indications for our pipeline of drug candidates.

Broaden the functionality of our XmAb Fc technology platforms.

We are conducting further research into the function and application of antibody Fc domains in order to expand the scope of our XmAb Fc technology platforms.

We use the modularity of our XmAb bispecific Fc domains to engineer XmAb drug candidates in a variety of structural formats.

Continue to expand our patent portfolio protecting our Fc technologies and XmAb drug candidates.

We seek to expand our intellectual property estate and protect our proprietary Fc technologies, our development programs, and XmAb drug candidates by filing and prosecuting patents in the United States (U.S.) and other countries.

Where appropriate, we will seek expansion and extension of patents issued for our product candidates and for partnered product candidates that incorporate our Fc technologies.

Applications of our protein engineering technologies include multi-specific antibodies that engage two or more targets simultaneously, creating entirely new biological mechanisms of anti-disease activity, or enhancement of antibody performance by increasing immune inhibitory activity, improving cytotoxicity, extending circulating half-life and stabilizing novel protein structures.

Three marketed medicines have been developed with our XmAb protein engineering technologies.

XmAb Bispecific Fc Domain and Multi-Specific Antibody Formats

Our modular approach to protein engineering is a distinguishing feature of our Fc technologies.

This inherent flexibility enables us to design multiple XmAb drug candidates with distinct and novel mechanisms-of-action and to seek out new applications of the XmAb Bispecific Fc Domain.

Our business, research, and clinical efforts are to develop and advance our Fc technologies and our portfolio of XmAb drug candidates in oncology and autoimmune diseases.

CD3 candidates:

CD3 T-cell engaging bispecific antibodies are designed to redirect T cells to target cells through the engagement of an antigen on target cells and CD3, an activating receptor on T cells.

We have significantly expanded the potential of our CD3 T-cell engagers with the multi-specific XmAb 2+1 bispecific antibody format, utilizing two identical antigen binding domains and one CD3 targeting domain.

The affinities for antigen binding are engineered to enable selective engagement and killing of high antigen-expressing target cells over low antigen-expressing normal cells.

In preclinical cancer models, XmAb 2+1 bispecific antibodies bound preferentially to tumor cells compared to normal cells and effectively recruited T cells to kill tumor cells selectively.

We believe that these properties will be particularly important when developing bispecific antibodies against many solid tumor targets, where standard monovalent targeting of tumor antigens could lead to poor tolerability because such targets are often expressed on a range of normal tissues, including critical organs.

Our XmAb819 and XmAb541 CD3 candidates, which are being developed for patients with solid tumors, have been designed using our CD3 2+1 format.

We have leveraged our XmAb protein engineering platforms to create XmAb657, a potent, potentially long-acting CD19 x CD3 bispecific antibody, utilizing the XmAb 2+1 bispecific antibody format and Xtend Fc technology.

In non-human primate studies, a single dose of XmAb657 deeply reduced B cells by over 99.98% in the peripheral compartment, bone marrow and lymph nodes, which was sustained for at least 28 days.

Half-life was estimated to be 15 days, which indicates a potential for durable B-cell depletion in clinical studies.

XmAb657 was well tolerated preclinically, with no clinical signs of cytokine release syndrome.

We plan to initiate a first-in-human study during the second half of 2025.

TL1A x IL-23:

We believe a drug candidate to potentially emerge from our TL1A x IL-23 program could address significant unmet medical needs for patients with inflammatory bowel diseases (IBD), such as Crohn’s disease and ulcerative colitis, the two most common forms of IBD.

An engineered XmAb TL1A x IL-23p19 bispecific antibody could potentially provide dual targeting of important inflammatory pathways for autoimmune and inflammatory disease, while avoiding the complexities of dosing and formulary access for two separate TL1A and IL23 targeted drugs.

We anticipate selecting a lead candidate in 2025 and initiating first-in-human studies during 2026.

CD28 candidates:

T cells in the tumor microenvironment require both T-cell receptor (TCR) and co-stimulatory receptor engagement to achieve full activation.

CD28 is a key immune co-stimulatory receptor on T cells;

however, the ligands that activate T cells through CD28 are often not expressed on tumor cells.

Targeted CD28 T-cell engaging bispecific antibodies may provide conditional co-stimulation of T cells, for example, to T cells recognizing neoantigens or

in concert with CD3 T-cell engaging bispecific antibodies.

Our XmAb808 CD28 candidate has been engineered to provide selective CD28 co-stimulation of T cells, activating them when bound to tumor cells.

We continue to invest in our protein engineering efforts to identify novel technologies and drug candidates.

Other XmAb Fc Domains

We have also created additional XmAb Fc domains, and we have successfully entered partnerships for these technologies and for XmAb drug candidates that incorporate them.

We continue to seek additional partnering and licensing opportunities for these Fc domains.

Additional XmAb Fc domains include:

Immune Inhibitor Fc Domain – selective immune inhibition and rapid target clearance, targeting the receptor FcγRIIb;

Cytotoxic Fc Domain – increased cytotoxicity, targeting the receptors FcγRIIIa on natural killer (NK) cells and FcγRIIa on other immune system cells;

Xtend™ Fc Domain – extended antibody half-life, targeting the receptor FcRn on endothelial cells.

Drug Candidates in Clinical Development

This flexibility enables us to design multiple XmAb drug candidates with distinct and novel mechanisms of action and to explore new applications of the XmAb Bispecific Fc Domain.

Our business, research, and clinical efforts focus on developing and advancing a portfolio of XmAb drug candidates in oncology and autoimmune diseases.

• CD3 bispecific antibodies :

CD3 T-cell engaging bispecific antibodies are designed to redirect T cells to target cells by engaging an antigen on the target cell and CD3, an activating receptor on T cells.

We have expanded the potential of our CD3 T-cell engagers through the development of the multi-specific XmAb 2+1 bispecific antibody format, which incorporates two identical target-binding domains and one CD3-binding domain.

Target-binding affinities are engineered to enable selective engagement and killing of cells with high target expression while minimizing activity against normal cells with low target expression.

In preclinical cancer models, XmAb 2+1 bispecific antibodies preferentially bound to tumor cells over normal cells and effectively recruited T cells to selectively kill tumor cells.

These properties may be particularly important for solid tumor targets, where conventional monovalent targeting can result in limited tolerability due to target expression on normal tissues, including critical organs.

XmAb819 and XmAb541 are examples of our CD3 candidates in clinical development for solid tumors that were designed using this 2+1 format.

Plamotamab and XmAb657, which uses a 2+1 format, are examples of our CD3 candidates in clinical development for autoimmune diseases.

• CD28 bispecific antibodies :

T cells in the tumor microenvironment require both T-cell receptor engagement and co-stimulatory signaling to achieve full activation.

CD28 is a key co-stimulatory receptor on T cells;

however, its natural ligands are often not expressed on tumor cells.

Targeted CD28 T-cell engaging bispecific antibodies may enable conditional co-stimulation of T cells, such as in the presence of tumor-associated antigens or in combination with CD3 T-cell engaging bispecific antibodies.

XmAb808, our clinical-stage CD28 candidate, has been engineered to provide selective CD28 co-stimulation, activating T cells upon binding to B7-H3 expressed on tumor cells.

• XmAb412 (TL1A x IL23p19) :

XmAb412 is a bispecific antibody that inhibits both TL1A and IL23p19, two important inflammatory pathways for autoimmune and inflammatory disease, while avoiding the complexities of development, dosing and formulary access for two separate TL1A and IL23 monospecific drugs.

In vitro studies show that XmAb412 matches the target inhibition potency of monospecific antibodies to these targets, but in a

bispecific format.

XmAb412 could address significant unmet medical needs for patients with inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis.

We anticipate initiating first-in-human studies during 2026.

Additional XmAb Fc domains that we have developed include:

• Immune Inhibitor Fc Domain :

Designed to provide selective immune inhibition and rapid target clearance through engagement of the FcγRIIb receptor.

• Cytotoxic Fc Domain :

Engineered to enhance cytotoxic activity through engagement of FcγRIIIa receptors on natural killer cells and FcγRIIa receptors on other immune system cells.

• Xtend™ Fc Domain :

Designed to extend antibody half-life through engagement of the FcRn receptor on endothelial cells.

XmAb942 is an antibody that targets TL1A and is in clinical development for inflammatory bowel diseases that uses our Xtend Fc domain.

Our goal is to become a leading biopharmaceutical company that develops and commercializes engineered biologic medicines to advance the standard of care for patients with severe and life-threatening diseases.

Key elements of our strategy include the following:

Advance XmAb antibody programs in oncology and autoimmune diseases

We seek to advance multiple XmAb drug candidates into clinical development by leveraging protein engineering capabilities and our modular bispecific technologies.

We have aligned our portfolio to prioritize T cell-engaging bispecific antibody programs in oncology, which we believe represent an important emerging class of drugs that holds significant potential for the treatment of patients beyond current standard of care.

We employ a number of XmAb protein engineering technologies for our current portfolio of drug candidates to treat patients with cancer and with autoimmune and inflammatory diseases.

Build and actively manage a pipeline of XmAb drug candidates

We advance multiple XmAb drug candidates into early stages of clinical development and evaluate data generated from ongoing studies to inform further development decisions.

Based on emerging clinical data, competitive dynamics, and resource considerations, we may increase investment in certain programs, enter into partnerships with third-party biotechnology or pharmaceutical companies, or discontinue development of certain drug candidates.

Leverage protein engineering capabilities through partnerships and collaborations

We seek to utilize our protein engineering capabilities, XmAb Fc domains, XmAb multi-specific antibodies, and XmAb drug candidates in collaboration, licensing, and partnership arrangements to generate revenue while selectively retaining rights to advance certain prioritized programs internally, create new drug candidates, explore combination therapies, and identify additional indications for our pipeline programs.

Generate revenue through licensing and collaboration arrangements

The modular nature of our Fc technologies and our ability to efficiently generate multiple drug candidates provide opportunities to generate revenue from licensing and collaboration agreements with third parties.

Create new XmAb drug candidates and evaluate combination therapies

We aim to leverage our XmAb Fc domains and protein engineering technologies, independently and with partners, to create novel XmAb drug candidates and, where appropriate, to evaluate our candidates in combination with other therapeutic agents.

Expand the functionality of XmAb technology platforms

We continue to conduct research into the function and application of multi-specific antibodies to broaden the scope of our XmAb technology platforms.

Our modular designs allow us to engineer XmAb drug candidates across a range of structural formats and biological functions.

We are engineering new molecular formats based on our Fc domains to develop novel molecules for engaging three targets simultaneously, called trispecific antibodies, to create highly specific cancer therapies, while overcoming the inherent structural and stability problems for standard trispecific molecules.

Protect and expand our intellectual property portfolio

We seek to protect our proprietary XmAb technologies and XmAb drug candidates by filing and prosecuting patents in the United States and other jurisdictions.

Where appropriate, we pursue the expansion and extension of patent coverage for our proprietary and partnered programs incorporating our XmAb technologies.

XmAb Drug Candidates in Clinical Development

Wholly Owned Developed by Partners Marketed by Partners

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Novartis antibody

Xpro1595/INB03

Zaltenibart (OMS906)

* Alexion and Incyte are conducting additional Phase 3 studies in new indications.

We regularly evaluate our portfolio of candidates and make additional investments in candidates with promising early-stage clinical data, partner out other candidates, and stop development of candidates where early clinical data does not support further investment by us.

• We reacquired exclusive worldwide rights to plamotamab and subsequently announced new Phase 1b/2a clinical development plans for plamotamab in rheumatoid arthritis (RA);

• We announced new XmAb drug candidates, XmAb942 and XmAb657, to be evaluated for the treatment of patients with autoimmune and inflammatory diseases;

• We initiated first-in-human studies for our XmAb541 and XmAb942 programs;

• We presented early data from the Phase 2 monotherapy study of vudalimab in patients with clinically defined high-risk metastatic castration-resistant prostate cancer (mCRPC);

• We concluded the Phase 1 development programs evaluating our internally developed cytokine programs, XmAb564 and XmAb662, and paused further development.

• We presented initial results from the ongoing Phase 1 dose-escalation study of XmAb819 in advanced clear cell renal cell carcinoma and presented early efficacy data from a cohort in the ongoing Phase 1 dose-escalation study of XmAb541 in advanced gynecologic and germ cell tumors;

• We presented initial data from a Phase 1 study of XmAb942 in healthy volunteers and initiated a global Phase 2b study of XmAb942 in ulcerative colitis (XENITH-UC);

• We initiated a Phase 1b proof-of-concept study of plamotamab for patients with rheumatoid arthritis who have progressed through prior standard-of-care treatment;

• We initiated a Phase 1 proof-of-concept study of XmAb657 for patients with idiopathic inflammatory myopathies;

• We selected XmAb412 as our lead TL1A x IL23p19 bispecific antibody drug candidate;

• We paused further development of vudalimab, a PD-1 x CTLA-4 bispecific antibody, and decided not to initiate expansion cohorts of XmAb808 in combination with pembrolizumab.

Wholly Owned Clinical-Stage XmAb Drug Candidates

Our modular XmAb technologies and protein engineering capabilities enable us to rapidly advance multiple drug candidates into clinical development.

We are currently enrolling Phase 1 studies for three wholly-owned candidates to treat patients with many different types of serious diseases:

XmAb819, XmAb541 and XmAb942.

Two additional drug candidates are planned to enter clinical development in 2025:

plamotamab and XmAb657.

We are currently enrolling Phase 1 or Phase 2 studies for five wholly-owned candidates to treat patients with many different types of serious diseases:

XmAb819, XmAb541, XmAb942, plamotamab and XmAb657.

Oncology Programs

XmAb819 (ENPP3 x CD3) :

XmAb819 is a first-in-class, tumor-targeted, T-cell engaging XmAb 2+1 bispecific antibody in development for patients with clear cell renal cell carcinoma (ccRCC).

XmAb819 engages the immune system and activates T cells for highly potent and targeted lysis of tumor cells expressing ENPP3, an antigen highly expressed on kidney cancers.

ENPP3 is a differentially expressed target, with high level expression in renal cell carcinoma (RCC) and low level expression on normal tissues.

With two tumor-antigen binding domains and one T-cell binding domain, our XmAb 2+1 format enables antibodies to bind more avidly and selectively kill tumor cells with higher antigen density, potentially sparing normal cells.

XmAb819 is a novel, potential first-in-class, tumor-targeted, T-cell engaging XmAb 2+1 bispecific antibody in development for patients with clear cell renal cell carcinoma (ccRCC).

XmAb819 is designed to engage the immune system and activate T cells for highly potent and targeted lysis of tumor cells expressing ENPP3, an antigen highly expressed on kidney cancers.

ENPP3 is a differentially expressed target, with high level expression in RCC and low level expression on normal tissues.

With two tumor-antigen binding domains and one T-cell binding domain, our XmAb 2+1 format is designed to enable antibodies to bind more avidly and selectively kill tumor cells with higher antigen density, potentially sparing normal cells.

We are conducting a Phase 1 study to evaluate XmAb819 in patients with advanced ccRCC.

In September 2024, we announced that initial evidence of anti-tumor activity had been observed in dose-escalation cohorts in the ongoing Phase 1 study, including RECIST responses, and the duration of treatment for several patients in earlier dose cohorts has extended beyond one year.

Cytokine release syndrome remained manageable, and the tolerability profile from recent dose cohorts, including no maximum tolerated dose being reached, supported continued dose escalation toward target dose levels.

At the AACR-NCI-EORTC Conference on Molecular Targets and Cancer Therapeutics in October 2025, we presented initial results from the Phase 1 dose-escalation study.

As of the data cut-off, 69 patients had received XmAb819 across 15 dose cohorts;

patients were heavily pre-treated, having received a median of 4 prior lines of therapy.

All patients received prior anti-PD1 therapy and prior VEGF-TKI therapy, and 36% of patients were previously treated with a HIF2α inhibitor.

XmAb819 demonstrated evidence of anti-tumor activity and an acceptable safety profile that was generally well tolerated across dose levels.

Of the 20 efficacy-evaluable patients treated at the dose levels that were preclinically predicted to be within the target dose range, 25% achieved a partial response (4 confirmed PR and 1 unconfirmed PR, per RECIST v1.1) as best response with a 70% disease control rate.

The most common treatment-emergent adverse events (AEs) were

cytokine release syndrome, rash and gastrointestinal-related toxicities that were primarily Grade 1 or 2 in severity and predominantly associated with prime-step dosing in the first four weeks of treatment.

No cases of treatment-related immune effector cell-associated neurotoxicity syndrome (ICANS) were observed.

No Grade 5 events were reported.

Four patients (6%) were dose-reduced due to treatment-related AEs, and three patients (4%) discontinued treatment due to treatment-related AEs.

The dose-expansion portion of the current Phase 1 study is enrolling patients and dose-escalation continues in RCC.

We have initiated tumor expansion cohorts in colorectal cancer (CRC), non-small cell lung cancer (NSCLC) and papillary renal cell carcinoma (pRCC).

XmAb541 (CLDN6 x CD3) :

XmAb541 is a first-in-class, tumor-targeted, T-cell engaging XmAb 2+1 bispecific antibody in development for patients with Claudin-6 (CLDN6) expressing tumor types including ovarian cancer.

XmAb541 targets CLDN6, a tumor-associated antigen in ovarian cancer and other solid tumors, and CD3.

XmAb541 is a novel, potential first-in-class, tumor-targeted, T-cell engaging XmAb 2+1 bispecific antibody in development for patients with CLDN6 expressing tumor types including ovarian cancer.

XmAb541 is designed to engage the immune system and activate T cells for highly potent and targeted lysis of tumor cells expressing CLDN6, a tumor-associated antigen in ovarian cancer, germ cell tumors and other solid tumors.

The XmAb 2+1 multivalent format used in XmAb541 enables greater selectivity for CLDN6 over similar Claudin family members, such as CLDN9, CLDN3 and CLDN4.

We are conducting a Phase 1 study to evaluate XmAb541 in patients with ovarian cancer and other CLDN6 expressing tumor types.

The first patient was dosed in April 2024.

The Phase 1 dose-escalation study is ongoing, with characterization of target dose levels anticipated to begin during 2025.

We are conducting a Phase 1 dose-escalation study to evaluate XmAb541 in patients with advanced gynecologic and germ cell tumors.

In October 2025 we presented early efficacy data from a cohort in the ongoing Phase 1 dose-escalation study.

As of the data cut-off, nine patients received XmAb541 in the most recently completed escalation cohort.

Confirmed partial responses per RECIST v1.1 were observed in three patients:

one patient with ovarian cancer and two patients with germ cell tumors.

XmAb808 (B7-H3 x CD28) :

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Co-stimulation is required for T cells to achieve full activation, and targeted CD28 bispecific antibodies may provide conditional co-stimulation of T cells when the antibodies are bound to tumor cells.

We are conducting a Phase 1 study to evaluate XmAb808 in combination with pembrolizumab in patients with advanced solid tumors.

In September 2024, we presented a clinical update on the ongoing Phase 1 study.

The majority of patients enrolled into the study were men with mCRPC.

In this group of patients, prostate specific antigen (PSA) declines were observed during the four-week monotherapy safety run-in period.

In November 2024, we announced that within the range of expected active doses, two patients experienced dose-limiting toxicities as defined in the study protocol.

The maximum tolerated dose was not defined per protocol.

As the data were analyzed, back-fill enrollment proceeded in the next lower dose cohort, a dose within the range of target doses which was determined to be tolerable.

Dose escalation resumed late in the fourth quarter of 2024, and enrollment in the final dose-escalation cohort is complete.

Data from the study are expected to inform future development decisions for the program.

Data from completed cohorts in a Phase 1 dose-escalation study of XmAb808 in combination with pembrolizumab, an anti-PD1 antibody, are expected to inform future development decisions for the program.

Potential combination with CD3 T-cell engaging bispecific antibodies is being evaluated.

Vudalimab (PD-1 x CTLA-4):

Vudalimab is a bispecific antibody that targets PD-1 and CTLA-4, two immune checkpoint receptors, to selectively activate the tumor microenvironment.

In the fourth quarter of 2024, we completed enrollment in two studies of vudalimab in patients with mCRPC and in Part 1 of a study in patients with locally advanced or metastatic non-small cell lung cancer.

We have paused further development of vudalimab and have prioritized resources to advance other pipeline programs.

Safety data from the three studies of vudalimab remain consistent with prior data disclosures.

Autoimmune Disease Programs

In September 2024, we announced new clinical development plans for plamotamab and announced new XmAb drug candidates to be evaluated for the treatment of patients with autoimmune and inflammatory diseases.

We believe that plamotamab and XmAb657 could address significant unmet needs for patients with a wide-range of autoimmune diseases that could be responsive to targeted B-cell depletion, such as RA, multiple sclerosis, advanced systemic lupus erythematosus, anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis, idiopathic inflammatory myopathy, myasthenia gravis, neuromyelitis optica spectrum disorder, pemphigus vulgaris, Sjogren’s syndrome, and systemic sclerosis.

We believe that XmAb942 could address significant unmet medical needs for patients with IBD, such as Crohn’s disease and ulcerative colitis, the two most common forms of IBD.

XmAb942 (Xtend TL1A) :

XmAb924 is a monospecific anti-TL1A antibody, utilizing Xencor’s Xtend Fc domain and proprietary Fc silencing technology, with potentially class-leading potency, and is under development for people with IBD.

The two most common forms of IBD are Crohn’s disease and ulcerative colitis.

In October 2024, preclinical data were presented during United European Gastroenterology (UEG) Week.

Preclinical half-life was 23 days, potentially supporting an 8- to 12-week dosing regimen in humans.

In the fourth quarter of 2024, we initiated dosing of healthy volunteers in the first-in-human study of XmAb942, and we expect initial single-ascending dose data from a Phase 1 study in healthy volunteers during the first half of 2025.

We continue to expect data from the multiple-ascending dose portion of study and the initiation of a Phase 2 study in patients with ulcerative colitis in the second half of 2025.

XmAb942 is a high-potency, extended half-life, investigational anti-TL1A antibody in clinical development for patients with inflammatory bowel disease (IBD), such as ulcerative colitis (UC) and Crohn’s disease (CD).

The first generation of anti-TL1A antibodies, designed to block the interaction between the DR3 receptor and its ligand TL1A, have reduced disease activity in patients with UC and CD in multiple clinical studies.

We announced interim results from a Phase 1 dose-escalation study in healthy volunteers in April 2025.

The results indicate that XmAb942 was well tolerated at single and multiple doses.

Pharmacokinetic analysis of the single dose cohorts estimated a human half-life of greater than 71 days, which supports a 12-week dosing interval during maintenance treatment.

We initiated a Phase 2b study of XmAb942 in UC, the XENITH-UC Study, in the third quarter of 2025.

XENITH-UC is a randomized, double-blind, placebo-controlled trial in patients with moderate-to-severe UC, whose disease has progressed after at least one conventional or advanced therapy.

Plamotamab (CD20 x CD3) :

Plamotamab is a B-cell depleting bispecific T-cell engager that targets CD20, a target receptor on B cells, and CD3.

Results from the expansion portion of a Phase 1 study indicate that intravenous plamotamab monotherapy was well tolerated and demonstrated encouraging clinical activity in heavily pretreated patients with an advanced form of lymphoma at the recommended Phase 2 intravenous dose.

In 2023, we completed patient enrollment in subcutaneous dose escalation cohorts of the Phase 1 study.

We had been co-developing plamotamab with Johnson & Johnson (J&J), and in June 2024, we regained exclusive worldwide rights to develop and commercialize the candidate.

We plan to initiate a Phase 1b/2a proof-of-concept study for plamotamab in RA in the first half of 2025.

The Phase 1b portion of the study will select a priming and step-up dose regimen based on the regimen established in oncology, and will assess the initial safety, efficacy, and biomarkers of plamotamab in patients with RA.

The selected dose regimen will then be evaluated in the randomized Phase 2a portion, with efficacy determined at week 12.

Results from the Phase 1 study in hematologic cancers showed favorable tolerability and comparable preliminary efficacy data, when cross compared to results from studies of a competitor molecule within the class, with similar patient baseline characteristics.

Plamotamab is a B-cell depleting bispecific T-cell engager that targets CD20, a target receptor on B cells.

In the second quarter of 2025, we received regulatory authorization to initiate a Phase 1b proof-of-concept study for plamotamab in rheumatoid arthritis (RA), and we initiated the study in the third quarter of 2025.

The study will select a priming and step-up dose regimen based on the regimen established in oncology, and will assess the initial safety, efficacy and biomarkers of plamotamab in patients with RA.

Results from the previously conducted Phase 1 study in hematologic cancers showed favorable tolerability and comparable preliminary efficacy data, when cross compared to results from studies of a competitor molecule within the class, with similar patient baseline characteristics.

Data demonstrating deep peripheral B-cell depletion observed in patients with lymphoma were presented at a medical meeting in December 2024.

Based on these clinical outcomes, significant B-cell depletion, and the emergent biology supportive of B-cell targeted T cell engagers for the treatment of patients with autoimmune diseases, we plan to evaluate plamotamab in RA, in which patients progressed through prior standard of care treatment.

Additional Clinical-Stage XmAb Drug Candidate

XmAb7195 (anti-IgE) :

XmAb7195 uses our XmAb Immune Inhibitor Fc Domain and is designed to reduce blood levels of IgE, which mediates allergic responses and allergic disease.

In February 2020, we licensed this drug candidate to Aimmune Therapeutics, Inc., now a wholly owned subsidiary of Nestlé S.A.

We reacquired exclusive worldwide rights to XmAb7195 in 2024 and are evaluating development opportunities.

Collaborations, Partnerships and Licensing Arrangements

A key part of our business strategy is to leverage our protein engineering capabilities, XmAb technologies, and XmAb drug candidates with partnerships, collaborations, and licenses.

Based on these clinical outcomes, significant B-cell depletion, and the emergent biology supportive of B-cell targeted T-cell engagers for the treatment of patients with autoimmune diseases, we are evaluating plamotamab in RA, in which patients progressed through prior standard-of-care treatment.

XmAb657 (CD19 x CD3) :

XmAb657 is a potent, potentially long-acting CD19 x CD3 bispecific antibody, utilizing the XmAb 2+1 bispecific antibody format and Xtend Fc technology.

In non-human primate studies, a single dose of XmAb657 deeply reduced B cells by over 99.98% in the peripheral compartment, bone marrow and lymph nodes, which was sustained for at least 42 days.

Half-life in non-human primates was estimated to be 15 days, which indicates a potential

for durable B-cell depletion in human clinical studies.

XmAb657 was well tolerated preclinically, with no clinical signs of cytokine release syndrome.

XmAb657 is in development for patients with idiopathic inflammatory myopathies (IIM).

We initiated a first-in-human, Phase 1 study in the fourth quarter of 2025.

Collaborations, Partnerships and Licensing Arrangements for Approved or Authorized Medicines and Clinical-Stage Programs Engineered with XmAb Fc Domains

A key part of our business strategy is to leverage our protein engineering capabilities, XmAb Fc domains and drug candidates with partnerships, collaborations and licenses.

Through these arrangements we generate revenues in the form of upfront payments, milestone payments and royalties.

For partnerships for our drug candidates, we aim to retain a major economic interest in these candidates through transactions that allow us to retain major geographic commercial rights, provide for profit-sharing on future sales of approved products, include co-development options, and also the right to conduct independent clinical studies with drug candidates developed in the collaboration.

Types of Arrangements

Product licenses are arrangements in which we license to third parties partial or full rights to develop and commercialize our internally developed drug candidates.

We seek partners that can provide infrastructure and resources to successfully develop our drug candidates, have a track record of successfully developing and commercializing medicines, or have a portfolio of development-stage candidates and commercialized medicines which could potentially be developed in rational combinations with our drug candidates.

Examples include Genentech, Incyte Corporation, Zenas BioPharma, Inc., and INmune Bio, Inc.

Novel bispecific antibody collaborations are arrangements in which our partner seeks to create an XmAb bispecific antibody using one or more of our bispecific technologies.

Our partners provide an antibody or an antigen against tumors, and we conduct limited research and development activities to create potential bispecific antibody candidates for further development and commercialization by our partners.

Examples include J&J, Astellas Pharma Inc.

(Astellas), and Amgen Inc.

Technology licensing agreements are arrangements in which we license access to one or more of our XmAb Fc technologies on a restricted basis, typically to our XmAb Cytotoxic Fc Domain and/or our Xtend Fc Domain.

Our partners are responsible for all research, development and commercialization activities of the drug candidates.

The plug-and-play nature of XmAb Fc domains allows us to license access to our platforms with no internal research and development activities required of us.

Examples include Alexion Pharmaceuticals, Inc., Vir Biotechnology, Inc.

(Vir), Gilead Sciences, Inc., Omeros Corporation, and Novartis Institutes for BioMedical Research, Inc.

Strategic collaborations are arrangements where we believe we can create synergies between our partners’ capabilities and assets and our own protein engineering capabilities, Fc technologies and XmAb drug candidates.

Through these arrangements we seek to create new drug candidates, investigate novel combination therapies and potentially identify additional indications for our portfolio of XmAb drug candidates.

An example is Caris Life Sciences.

Clinical-Stage Drug Candidates Advanced by Partners

Xaluritamig is a STEAP1 x CD3 2+1 bispecific T-cell engager that our partner Amgen is advancing for the treatment of patients with prostate cancer.

The XmAb 2+1 multivalent format enables higher binding capability for STEAP1 expressing cells.

Results from a Phase 1 study evaluating xaluritamig in patients with mCRPC were presented at the European Society for Medical Oncology (ESMO) Congress in September 2024.

With a median follow-up time of 27.9 months, the median overall survival (OS) was 17.7 months across all cohorts.

A PSA90 rate of 45.1% was also observed in high-dose cohorts, and PSA90 response was associated with survival (p = 0.0044), which Amgen believes could potentially serve as an early indicator for benefit in these patients.

Amgen initiated a Phase 3 study of xaluritamig in patients with mCRPC who have previously been treated with taxane-based chemotherapy.

Multiple Phase 1 or Phase 1b studies evaluating xaluritamig as a monotherapy or in combination are enrolling patients with earlier prostate cancer.

Obexelimab targets CD19 with its variable domain and uses our XmAb Immune Inhibitor Fc Domain, which is designed to inhibit the function of B cells, an important component of the immune system.

In November 2021, we licensed this drug candidate to Zenas BioPharma, Inc., which is conducting a Phase 3 study in patients with immunoglobulin G4-related disease (IgG4-RD), a Phase 2 study in patients with relapsing multiple sclerosis and a Phase 2 study in patients with systemic lupus erythematosus.

Teropavimab and zinlirvimab are broadly neutralizing antibodies that incorporate our XmAb Fc technologies.

Gilead Sciences, Inc.

is advancing teropavimab and zinlirvimab in combination with lenacapavir as a long-acting treatment for virologically suppressed people living with human immunodeficiency virus (HIV) in a Phase 2 study.

Tobevibart is a neutralizing antibody that uses our XmAb Xtend Fc Domain and our XmAb Cytotoxic Fc Domain.

Vir is advancing tobevibart as a potential treatment for patients with hepatitis Delta virus infection.

Vir is conducting a Phase 2 combination study and is advancing the combination into a Phase 3 registrational clinical program.

Novartis is conducting a Phase 2 study evaluating an undisclosed antibody drug candidate that uses one of our XmAb Fc technologies.

Xpro1595 is a proprietary tumor necrosis factor (TNF) inhibitor candidate which we licensed to INmune Bio, Inc., in October 2017.

INmune is currently advancing Xpro1595 through clinical development for patients with Alzheimer’s disease and treatment-resistant depression.

Zaltenibart (OMS906) is an antibody targeting mannan-binding lectin-associated serine protease-3 (MASP-3) that uses our XmAb Xtend Fc Domain.

Omeros Corporation is conducting multiple Phase 2 studies evaluating zaltenibart for the treatment of patients with paroxysmal nocturnal hemoglobinuria (PNH) and other alternative pathway disorders.

ASP2138 is a Claudin-18.2 x CD3 2+1 bispecific antibody that our partner Astellas is advancing for the treatment of patients with gastric, gastroesophageal junction and pancreatic cancers.

The XmAb 2+1 multivalent format enables higher binding capability for Claudin-18.2 expressing cells.

Astellas is conducting a Phase 1 study evaluating ASP2138.

JNJ-9401 is a PSMA x CD28 bispecific antibody that J&J is advancing for the treatment of patients with prostate cancer.

J&J is conducting a Phase 1 study of JNJ-9401, which was developed with J&J under our 2020 collaboration.

JNJ-1493 is a CD20 x CD28 bispecific antibody that J&J is advancing for the treatment of patients with B-cell malignancies.

J&J is conducting a Phase 1 study of JNJ-1493, which was developed with J&J under our 2021 collaboration.

Efbalropendekin alfa (XmAb306/RG6323) is a reduced-potency IL15/IL15Rα-Fc fusion protein that incorporates our Xtend extended half-life technology, and we previously co-developed this program in collaboration with Genentech, a member of the Roche Group.

In the fourth quarter of 2023, we agreed with Genentech to convert our development cost and profit-sharing arrangement into a royalty and milestone payment-based arrangement.

Pursuant to the terms of the amended agreement with Genentech, effective June 1, 2024, Genentech assumed sole responsibility over all clinical, regulatory and commercial activities.

Genentech is not currently enrolling new patients into clinical studies to evaluate efbalropendekin alfa.

Our partners are conducting preclinical studies of additional drug candidates engineered with our XmAb Fc Domains.

Approved or Authorized Medicines Engineered with XmAb Fc Domains

Currently three medicines that have been developed with our XmAb Fc domains are now marketed or made available by our partners.

• Ultomiris ® (ravulizumab-cwvz) :

Alexion’s Ultomiris is approved in the U.S., Europe, and Japan for the treatment of certain patients with PNH, certain patients with atypical hemolytic uremic syndrome (aHUS), certain patients with generalized myasthenia gravis (gMG) and certain patients with neuromyelitis optica spectrum disorder (NMOSD).

Alexion is also evaluating Ultomiris in a broad late-stage development program across additional hematology, nephrology and neurology indications.

Alexion used our Xtend™ Fc Domain to enhance the half-life of Ultomiris to allow for a longer duration of action, less frequent dosing and reduced patient burden of therapy compared to the previous generation therapy, Soliris ® .

Ultomiris and Soliris are registered trademarks of Alexion Pharmaceuticals, Inc.

• Monjuvi ® (tafasitamab-cxix) :

In 2020, the United States Food and Drug Administration (FDA) approved Monjuvi under accelerated approval.

Monjuvi is a humanized Fc-modified CD19 targeting immunotherapy indicated in combination with lenalidomide for the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) not otherwise specified, including DLBCL arising from low grade lymphoma, and who are not eligible for autologous stem cell transplant (ASCT).

For partnerships for our drug candidates, we aim to retain a major economic interest in the form of keeping major geographic commercial rights;

profit-sharing;

co-development options;

and the right to conduct studies with drug candidates developed in the collaboration.

The types of arrangements that we have entered into with partners include product licenses, novel bispecific antibody collaborations, technology licensing agreements and strategic collaborations.

Product Licenses

Product licenses are arrangements in which we have internally developed drug candidates and, based on a strategic review, licensed partial or full rights to third parties to continue development and potential commercialization.

We seek partners that can provide infrastructure and resources to successfully develop our drug candidates, have a track record of successfully developing and commercializing medicines, or have a portfolio of development-stage candidates and commercialized medicines that could potentially be developed in rational combinations with our drug candidates.

The FDA approved Monjuvi ® (tafasitamab-cxix) under accelerated approval in July 2020.

Monjuvi is a CD19-directed cytolytic antibody containing an XmAb Fc domain for improved cytotoxic potency and indicated in combination with lenalidomide for the treatment of adult patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL), including DLBCL arising from low grade lymphoma, and who are not eligible for autologous stem cell transplant (ASCT).

This indication is approved under accelerated approval based on overall response rate.

Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).

In August 2021, the European Commission granted conditional marketing authorization for Minjuvi ® (tafasitamab) in combination with lenalidomide, followed by tafasitamab monotherapy, for the treatment of adult patients with relapsed or refractory DLBCL who are not eligible for ASCT.

In addition to its approved indication, tafasitamab is being evaluated as a therapeutic option in an ongoing Phase 3 pivotal trial for first-line DLBCL.

In December 2024, Incyte announced positive full results from the pivotal study of tafasitamab in combination with lenalidomide and rituximab in relapsed or refractory follicular lymphoma and submitted a supplemental Biologics License Application.

In December 2024, Incyte announced positive full results from the pivotal study of tafasitamab in combination with lenalidomide and rituximab in relapsed or refractory follicular lymphoma (FL) and submitted a supplemental Biologics License Application, which was accepted in February 2025.

In June 2025, the FDA approved Monjuvi in combination with rituximab and lenalidomide for the treatment of adult patients with relapsed or refractory FL.

In January 2026, Incyte announced positive topline results from a pivotal study of Monjuvi as a first-line treatment for DLBCL and that they expect to file a supplemental Biologics License Application (sBLA) for the first-line treatment of adults with newly diagnosed DLBCL in the first half of 2026.

Tafasitamab was created and initially developed by us.

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and under the brand name Minjuvi ® in Europe and Canada.

Incyte has exclusive commercialization rights to tafasitamab outside the U.S.

In February 2024, Incyte acquired exclusive global development and commercialization rights to tafasitamab from MorphoSys AG.

Monjuvi ® and Minjuvi ® are registered trademarks of Incyte.

• Sotrovimab:

Vir and its partner GSK plc have made available sotrovimab, an antibody that targets the SARS-CoV-2 virus, which in May 2021 received an emergency use authorization (EUA) from the FDA for the early

treatment of mild-to-moderate COVID-19 in adults and pediatric patients (12 years of age and older weighing at least 40 kg) with positive results of direct SARS-CoV-2 viral testing, and at high risk for progression to severe COVID-19, including hospitalization or death.

In March 2022, the FDA deauthorized sotrovimab’s use in all U.S.

regions due to increases in the proportion of COVID-19 cases caused by the Omicron BA.2 subvariant.

Sotrovimab has obtained emergency authorization, temporary authorization or marketing approval (under the brand name Xevudy ® ) for early treatment of COVID-19 in more than 30 countries.

Sotrovimab incorporates our Xtend Fc domain for longer duration of action.

Xevudy is a registered trademark of GSK.

We are eligible to receive up to $195.0 million in future milestone payments and tiered royalties on net sales of Monjuvi that range from high-single-digit to low-double-digit percentages.

We earned $10.2 million in estimated non-cash royalties from Incyte for the year ended December 31, 2025.

Zenas BioPharma (“Zenas”) is advancing obexelimab, an antibody that targets CD19 with its variable domain, for the treatment of patients with autoimmune diseases.

Obexelimab uses an XmAb Fc domain that was designed to inhibit the function of B cells, an important component of the immune system.

Obexelimab was created and initially developed by us and was licensed to Zenas in November 2021.

Zenas’ partner, Bristol Myers Squibb, holds exclusive development and commercialization rights for obexelimab in Japan, South Korea, Taiwan, Hong Kong, Singapore, and Australia.

In October 2025, Zenas announced positive results from the Phase 2 MoonStone trial of obexelimab in patients with relapsing multiple sclerosis, in which the primary endpoint was met.

In January 2026, Zenas announced positive results from the Phase 3 INDIGO trial of obexelimab in patients with immunoglobulin G4-related disease (IgG4-RD), in which the primary endpoint was met.

Zenas announced that it anticipates submitting a biologics license application (BLA) to the U.S.

Food and Drug Administration for the treatment of IgG4-RD in the second quarter of 2026 and a Marketing Authorization Application (MAA) to the European Medicines Agency in the second half of 2026.

Zenas is also conducting a Phase 2 study of obexelimab in patients with systemic lupus erythematosus.

We are eligible to receive up to $460.0 million in future milestone payments and tiered royalties on net sales of obexelimab that range from mid-single-digit to mid-teen percentages, dependent on geography.

As of December 31, 2025, we own 3,098,380 shares of common stock in Zenas.

Novel Bispecific Antibody Collaborations

Novel bispecific antibody collaborations are arrangements in which our partner seeks to create a bispecific antibody using one or more of our XmAb bispecific technologies.

Our partners provide an antibody or a tumor-associated antigen, and we conduct limited research and development to create potential bispecific antibody candidates for further development and commercialization by our partners.

Xaluritamig is a STEAP1 x CD3 2+1 XmAb bispecific T-cell engager that our partner Amgen is advancing for the treatment of patients with prostate cancer.

The XmAb 2+1 multivalent format enables higher binding capability for STEAP1-expressing cells.

Results from a Phase 1 study evaluating xaluritamig in patients with metastatic castration-resistant prostate cancer (mCRPC) were presented in September 2024.

With a median follow-up of 27.9 months, median overall survival was 17.7 months across all cohorts.

A PSA90 response rate of 45.1% was observed in high-dose cohorts, and PSA90 response was associated with improved survival (p = 0.0044), which Amgen believes could potentially serve as an early indicator of clinical benefit in these patients.

In the third quarter of 2025, Amgen initiated the Phase 3 XALience study evaluating xaluritamig in combination with abiraterone versus investigator’s choice therapy in patients with chemotherapy-naïve mCRPC.

In addition, the Phase 3 XALute monotherapy study of xaluritamig in patients with mCRPC previously treated with taxane-based chemotherapy is ongoing.

Multiple Phase 1 and Phase 1b studies evaluating xaluritamig as a monotherapy or in combination are also enrolling patients with earlier prostate cancer.

We are eligible to receive up to $225.0 million in regulatory and sales milestone payments related to the xaluritamig program and tiered royalties on global net sales of approved products that range from mid- to high-single digit percentages.

ASP2138 is a bispecific Claudin 18.2 x CD3 bispecific antibody that Astellas is advancing for the treatment of patients with gastric, gastroesophageal junction or pancreatic cancers.

ASP2138 utilizes the XmAb 2+1 multivalent format to enable activation of T cells against CLDN18.2-expressing tumor cells.

In October 2025, the first clinical data from ASP2138, both as a monotherapy and in combination with standard-of-care therapies in gastric or gastroesophageal junction adenocarcinomas, were presented during the European Society for Medical Oncology (ESMO) congress in Berlin.

We are eligible to receive $232.5 million in future milestone payments and tiered royalties on net sales of ASP2138 that range from high-single to low-double digit percentages.

Janssen Biotech, a Johnson & Johnson Company :

JNJ-9401 is a PSMA x CD28 bispecific antibody that J&J is advancing for the treatment of patients with mCRPC.

In November 2020, we entered into an agreement with J&J (the J&J Agreement) to develop XmAb bispecific antibodies against CD28 and a prostate tumor target, for the potential treatment of patients with prostate cancer, and from the collaboration, J&J selected JNJ-9401, which is currently in a Phase 1 clinical study.

We are eligible to receive a total of $640.0 million in future milestone payments and tiered royalties on net sales that range from high-single-digit to low-double-digit percentages for products developed under the J&J Agreement.

JNJ-1493 is a CD20 x CD28 bispecific antibody that J&J is advancing for the treatment of patients with B-cell malignancies.

In October 2021, we entered into a second collaboration agreement with J&J (the Second J&J Agreement) to create and characterize CD28 bispecific antibody candidates against B-cell targets, and from the collaboration, J&J selected JNJ-1493, which is currently in a Phase 1 clinical study.

In 2023, J&J also selected two additional CD28 bispecific antibody candidates under the second agreement.

We are eligible to receive a total of $636.3 million in future milestone payments and tiered royalties on net sales that range from high-single-digit to low-double-digit percentages for products developed under the Second J&J Agreement.

Technology License Agreements

We enter into technology licensing agreements in which we license access to one or more of our XmAb Fc domains on a restricted basis.

Our partners are responsible for all research, development and commercialization activities of the drug candidates.

The plug-and-play nature of XmAb technologies allows us to license access to our platforms with limited or no internal research and development activities.

Alexion’s Ultomiris® uses Xtend Fc technology to enhance the half-life of Ultomiris to allow for a longer duration of action, less frequent dosing and reduced patient burden of therapy compared to the previous generation therapy, Soliris ® .

Ultomiris has received marketing authorizations in global markets for the treatment of patients with paroxysmal nocturnal hemoglobinuria (PNH), for certain patients with atypical hemolytic uremic syndrome (aHUS), for certain patients with generalized myasthenia gravis (gMG) and for certain patients with neuromyelitis optica spectrum disorder (NMOSD).

Alexion is also evaluating Ultomiris in a broad development program across additional hematology, nephrology and neurology indications.

Ultomiris and Soliris are registered trademarks of Alexion Pharmaceuticals, Inc.

We are eligible to receive a low-single-digit percentage royalty on net sales of Ultomiris.

We earned $70.1 million in estimated non-cash royalties from Alexion for the year ended December 31, 2025.

Vir Biotechnology, Inc.

(“Vir Bio”) is advancing tobevibart, a neutralizing antibody that incorporates an XmAb Fc domain with multiple enhanced features, as a potential treatment for patients with chronic hepatitis Delta (CHD).

In August 2019, we entered into an agreement with Vir Bio pursuant to which we granted Vir Bio a non-exclusive license to our Xtend technology for two infectious disease targets.

Vir Bio initiated a Phase 3 registrational study of tobevibart in combination with a small interfering ribonucleic acid (siRNA) in people living with CHD in March 2025, triggering a $2.0 million milestone payment to the Company, which was paid in the second quarter of 2025.

We are eligible to receive up to $65.0 million in future milestone payments and tiered royalties on net sales of tobevibart that range from low-single-digit to mid-single-digit percentages.

Novo Nordisk :

Zaltenibart is an antibody targeting mannan-binding lectin-associated serine protease-3 (MASP-3) that uses our XmAb Xtend Fc Domain.

In December 2025, Novo Nordisk acquired exclusive global development and commercialization rights to zaltenibart from Omeros Corporation.

Omeros conducted multiple Phase 2 studies evaluating zaltenibart for the treatment of patients with paroxysmal nocturnal hemoglobinuria (PNH) and other alternative pathway disorders.

We are eligible to receive up to $60.0 million in future milestone payments and royalties on net sales of zaltenibart in the mid-single-digit percentage range.

Teropavimab and zinlirvimab are broadly neutralizing antibodies that incorporate our XmAb Fc technologies.

Gilead Sciences, Inc.

For each antibody, we are eligible to receive up to $64.0 million in future milestone payments and tiered royalties on net sales of approved products in the low-single digit percentage range.

Novartis is conducting Phase 2 studies evaluating an undisclosed antibody drug candidate that uses one of our XmAb Fc technologies.

We are eligible to receive up to $69.0 million in future milestone payments and royalties on net sales in the low-single digit percentage range.

Refer to Part II, Item 8, Note 2, Collaboration and Licensing Agreements of the Notes to Consolidated Financial Statements included in this Annual Report on Form 10-K for a description of the key terms of our arrangements.

Our Research and Development Pipeline

We have used our XmAb Fc platforms and protein engineering capabilities to produce a growing pipeline of drug candidates in clinical and preclinical development.

These include multiple drug candidates using our bispecific Fc domain.

We continue to advance these candidates as additional options for clinical development by us or as out-licensing opportunities.

We also from time to time in-license antibody technologies and compounds from other companies which we believe may allow us to create potential product candidates by incorporating our own proprietary technologies.

These licenses may require us to pay upfront fees, development, and commercial milestone payments, and if commercial products are approved, royalties on net sales.

We have leveraged our XmAb Fc platforms and protein engineering capabilities to generate a growing pipeline of drug candidates in clinical and preclinical development, including multiple candidates that incorporate our bispecific Fc domain.

We continue to advance these candidates as potential programs for internal clinical development or for out-licensing to third parties.

From time to time, we also in-license antibody technologies and compounds from other companies that we believe may enable the creation of additional product candidates through the application of our proprietary technologies.

These in-licensing arrangements may require upfront payments, development and commercial milestone payments, and, if commercial products are approved, royalties based on net sales.

Market Opportunity

Oncology programs (XmAb819, XmAb541 and XmAb808)

We are actively advancing wholly owned T cell–engaging bispecific antibody drug candidates for the treatment of cancer, including XmAb819, XmAb541, and XmAb808.

Cancer is a broad group of diseases characterized by uncontrolled cell growth that can invade surrounding tissues and spread to other parts of the body, and it is the second leading cause of death in the United States.

According to the American Cancer Society, approximately 2.1 million new cancer cases and approximately 626,140 cancer-related deaths are expected in the United States in 2026.

The National Institutes of Health has estimated that, driven by population growth and aging, medical expenditures for cancer in the United States are projected to reach at least $245.6 billion in 2030.

Inflammatory bowel disease program (XmAb942)

XmAb942 is our wholly owned anti-TL1A antibody drug candidate that we are actively advancing in clinical development for the treatment of IBD.

According to the U.S.

Centers for Disease Control and Prevention, IBD affects an estimated 2.4 million to 3.1 million adults in the United States, with prevalence increasing over time.

The Crohn’s & Colitis Foundation estimates that approximately 70,000 new cases are diagnosed annually in the United States.

IBD includes ulcerative colitis, which primarily affects the colon, and Crohn’s disease, which can involve any part of the

gastrointestinal tract.

Common symptoms include abdominal pain, diarrhea, bloody stool, weight loss, bowel urgency, fatigue, and systemic complications, and the disease is associated with reduced quality of life, increased rates of hospitalization and surgery, and an elevated risk of colorectal cancer.

Despite the availability of multiple approved therapies, durable remission is achieved in only approximately 10% to 20% of patients, reflecting a substantial unmet medical need.

Many patients experience inadequate response, loss of response over time, or treatment-limiting side effects, and adherence can be challenging due to dosing frequency and administration burden.

According to GlobalData, the global market for therapies to treat Crohn’s disease and ulcerative colitis is projected to reach approximately $40 billion by 2032.

Rheumatoid arthritis program (Plamotamab)

Plamotamab is our wholly owned bispecific antibody drug candidate that we are advancing for the treatment of rheumatoid arthritis (RA).

RA is a chronic autoimmune and inflammatory disease in which the immune system attacks healthy tissues, primarily affecting the joints and leading to pain, swelling, progressive joint damage, and functional impairment.

According to the Arthritis Foundation, RA affects approximately 1.5 million adults in the United States.

Beyond joint involvement, RA can result in systemic complications affecting organs such as the heart, lungs, and eyes, and is associated with reduced quality of life, increased disability, and shortened life expectancy.

Despite the availability of multiple approved therapies, including biologic agents and targeted small molecules, many patients do not achieve sustained remission or experience loss of response over time, highlighting a continued unmet medical need, particularly among patients with moderate-to-severe or refractory disease.

According to GlobalData, the global market for rheumatoid arthritis therapies is projected to reach approximately $30 billion by 2030, reflecting the large patient population and ongoing demand for therapies that can provide durable disease control.

Idiopathic inflammatory myopathies program (XmAb657)

XmAb657 is our wholly owned bispecific antibody drug candidate that we are advancing for the treatment of idiopathic inflammatory myopathies (IIM).

IIM is a heterogeneous group of rare autoimmune disorders, including dermatomyositis, polymyositis, and inclusion body myositis, characterized by chronic muscle inflammation and progressive muscle weakness.

Estimates from patient advocacy organizations suggest that IIM affects approximately 75,000 individuals in the United States.

In addition to muscle weakness, patients with IIM may experience skin manifestations, difficulty swallowing, and serious systemic complications, including interstitial lung disease, which can be life-threatening.

Current treatment approaches rely primarily on corticosteroids and broad immunosuppressive therapies, which are often associated with significant long-term side effects and may not adequately control disease progression for many patients.

As a result, there remains a substantial unmet medical need for more targeted therapies that can improve functional outcomes and long-term disease management.

According to GlobalData, the global market for inflammatory myopathy therapies is projected to reach approximately $2.1 billion by 2031, reflecting the growing recognition of disease burden and the need for novel treatment options in this rare autoimmune indication.

We compete in an industry characterized by rapid technological advancement, intense competition, and a strong emphasis on proprietary products.

Our competitors include pharmaceutical and biotechnology companies, academic institutions, and other research organizations.

We compete for promising antibody-based therapeutic targets, technologies to optimize antibody design, and the recruitment and retention of highly qualified scientific and clinical personnel.

Many of our current and potential competitors have substantially greater scientific, research, and product development capabilities, as well as greater financial, marketing, sales, and human resources than we do.

In addition, numerous specialized biotechnology companies have formed collaborations with large, established pharmaceutical companies to support the research, development, and commercialization of competing products.

As a result, our competitors may be more successful than we are in developing, commercializing, and achieving market acceptance for products that compete with our drug candidates, which could render our product candidates obsolete or noncompetitive before we recover our development costs.

Competition in the fields of oncology and autoimmune disease drug development is intense, with hundreds of compounds in clinical development.

A number of large pharmaceutical companies and biotechnology companies are developing competing bispecific antibody platforms, many of which have advanced multiple drug candidates into clinical trials, including Amgen, Genmab A/S, Regeneron Pharmaceuticals, Inc., and Roche Holding AG.

We are developing bispecific antibody drug candidates engineered to direct cytotoxic T-cell activity against solid tumor cells by engaging either the CD3 or CD28 receptor on T cells and a target antigen on tumor cells.

Other companies conducting clinical trials of CD3- or CD28-based bispecific antibodies directed to solid tumor antigens include Amgen, Astellas, Context Therapeutics Inc., CytomX Therapeutics, Inc., Genmab A/S, Immunocore Holdings plc, Janux Therapeutics, Inc., Johnson & Johnson, Regeneron Pharmaceuticals, Inc., Roche Holding AG, Rondo Therapeutics, Inc., Takeda Pharmaceutical Co.

Ltd., Third Arc Bio, Inc., and Vir Biotechnology.

In addition, other antibodies, antibody-drug conjugates, and cell-based therapies are in development or approved for the treatment of cancer.

We are also developing bispecific antibody drug candidates designed to direct cytotoxic T-cell activity against B cells by engaging the CD3 receptor on T cells and either the CD20 or CD19 receptor on B cells.

Other companies conducting clinical trials of CD3-based bispecific antibodies directed to CD20 or CD19 for autoimmune diseases include Amgen, Candid Therapeutics, Inc., Cullinan Therapeutics, Inc., Novartis AG, and Roche Holding AG.

Additional antibodies and cell therapies are in development or approved for the treatment of autoimmune diseases.

We are developing antibody drug candidates that target the cytokine TL1A for the potential treatment of inflammatory bowel disease.

Other companies conducting clinical trials of anti-TL1A monospecific or bispecific antibodies include Absci Corp., Caldera Therapeutics, Inc., Merck & Co., Inc., Roche Holding AG, Sanofi S.A., Spyre Therapeutics, Inc., and Teva Pharmaceutical Industries Limited.

In addition, we are aware of other companies with development-stage programs that may compete with our drug candidates or those of our licensees in the future.

We expect competition to intensify as new therapies are approved and emerging technologies continue to evolve.

Human Capital Management

Our Employees and Commitment to Diversity, Equity, and Inclusion

Our Employees

Our ability to develop XmAb technologies, advance our programs into late-stage development, position our programs for commercialization and identify successful business partnerships is dependent on attracting, retaining, and developing our employees.

We seek and support a diverse population of employees without regard to race, gender or sexual orientation.

We seek to attract and support a diverse population of employees without regard to race, gender or sexual orientation.

As of December 31, 2025, we had 260 full-time employees, of which 212 were engaged in research and development activities, and 48 were engaged in business development, information systems, facilities, human resources, or administrative support.

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None of our employees are represented by any collective bargaining unit.

We believe we maintain good relations with our employees.

We are an equal opportunity employer and maintain policies that prohibit unlawful discrimination based on race, color, religion, gender, sexual orientation, gender identity/expression, national origin/ancestry, age, disability, marital and veteran status.

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In addition, as of December 31, 2025, women made up 25% of our senior leadership team.

We strive to build and nurture a culture where all employees feel empowered to be their authentic selves.

In January 2024, in connection with re-prioritization of our development programs, we completed a reduction in force (RIF) affecting approximately 10% of the total employee headcount.

The RIF was applied across all functional areas.

Compensation, Benefits, and Development

We provide compensation packages designed to attract, retain, and motivate high-quality employees.

All of our employees are eligible for cash bonuses and grants of equity awards.

We regularly evaluate our compensation programs with an independent compensation consultant and utilize industry benchmarking in an effort to ensure they are competitive compared to similar biotechnology and biopharmaceutical companies with which we compete for talent and that they are fair and equitable across our workforce with respect to gender, race, and other personal characteristics.

All employees are eligible for cash bonuses and grants of equity awards.

We regularly evaluate our compensation programs with an independent compensation consultant and utilize industry benchmarking in an effort to ensure that such programs are competitive compared to similar biotechnology and biopharmaceutical companies with which we compete for talent and are intended to be fair and equitable across the workforce with respect to gender, race, and other personal characteristics.

All employees are eligible to participate in our Employee Stock Purchase Plan through which they can purchase shares of our common stock at a discounted price.

This plan and our other equity compensation plans assist us in building long-term relationships with our employees and aligns the interests of employees with stockholders.

This plan and our other equity compensation plans assist us in building long-term relationships with our employees and align the interests of employees with stockholders.

We also provide retirement benefits along with a health and well-being program that is designed to keep our employees and their families healthy and includes paid time off and medical, dental and vision benefits, along with dependent care, mental health, and other wellness benefits.

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We regularly conduct employee surveys to assess employee engagement and identify areas for focus.

Market Opportunity

Our wholly owned drug candidates that we are actively advancing in clinical development in oncology indications, including XmAb819, XmAb541 and XmAb808 :

We are developing these T-cell engaging bispecific antibody drug candidates to treat cancer.

Cancer is a broad group of diseases in which cells divide and grow in an uncontrolled fashion, forming malignancies that can invade other parts of the body, and it is the second leading cause of death in the U.S.

The American Cancer Society estimates that in 2025 there will be approximately 2.0 million new cases of cancer and approximately 618,120 deaths from cancer.

The National Institutes of Health (NIH) has estimated that based on growth and aging of the U.S.

population, medical expenditures for cancer in the year 2030 are projected to reach at least $245.6 billion.

XmAb942, our wholly owned anti-TL1A antibody drug candidate that we are actively advancing in clinical development to treat IBD:

IBD is a chronic condition affecting an estimated 2.4 to 3.1 million adults in the United States, according to the U.S.

Centers for Disease Control and Prevention, with increasing prevalence.

The Crohn's and Colitis Foundation estimates that 70,000 new cases are diagnosed annually.

IBD includes ulcerative colitis, which inflames the colon’s lining, and Crohn’s disease, which can affect any part of the gastrointestinal tract.

Symptoms include abdominal pain, diarrhea, bloody stool, weight loss, bowel urgency, bloating, nausea, joint pain, fatigue, fever, reduced appetite and mental health impact.

Both conditions significantly impact patients’ quality of life, with lower life expectancy, surgeries and hospitalizations, and increased risk for both intestinal resection and colorectal cancer.

Despite available therapies, only 10% to 20% of patients achieve durable remission, highlighting a major unmet need.

Many experience inadequate response, loss of efficacy, or side effects.

Treatment adherence is also challenging due to frequent dosing and administration burdens.

GlobalData has estimated that the market size for the treatment of Crohn's disease and ulcerative colitis, the two most common forms of IBD, will reach $40 billion worldwide by the year 2032.

Intellectual Property

The foundation for our XmAb technology and our product candidates and partnering is the generation and protection of intellectual property for novel antibody therapeutics.

We combine proprietary computational methods for amino acid sequence design with laboratory generation and testing of new antibody compositions.

Our design and engineering team prospectively assesses, with patent counsel, the competitive landscape with the goal of building broad patent positions and avoiding third-party intellectual property.

As a pioneer in Fc domain engineering, we systematically scanned the structure of the Fc domain to discover Fc variants.

We have filed patent applications relating to thousands of specific Fc domain variants with experimental data on specific improvements of immune function, pharmacokinetics, structural stability, and novel structural constructs.

We have filed additional patent applications derived from these applications as we discover new properties of the Fc variants and as new business opportunities arise.

We continually seek to expand the intellectual property coverage of our technology and candidates and invest in discovering new Fc domain technologies and antibody product candidates.

Our patent estate, on a worldwide basis, includes issued patents and pending patent applications, with claims directed to XmAb Fc domains, all of our clinical and preclinical stage product candidates and our computational protein design methods and platforms.

The patent expiration in the U.S.

and major foreign countries (ex-U.S.) for our key technologies and drug candidates is set forth below.

We have pending applications filed that may extend the exclusivity of some of our technology and products:

Technology Patent Expiry

The foundation of our XmAb technology, product candidates, and partnering strategy is the generation and protection of intellectual property for novel antibody therapeutics.

We combine proprietary computational methods for amino acid sequence design with laboratory-based generation and testing of new antibody compositions.

Our design and engineering team evaluates the competitive intellectual property landscape in collaboration with patent counsel with the objective of building broad patent protection while minimizing the risk of third-party intellectual property infringement.

As a pioneer in Fc domain engineering, we have systematically analyzed the structure of the Fc domain to identify Fc variants with differentiated properties.

We have filed patent applications covering thousands of specific Fc domain variants supported by experimental data demonstrating improvements in immune function, pharmacokinetics, structural stability, and novel structural constructs.

As we identify new properties of these Fc variants and pursue additional business opportunities, we continue to file additional patent applications derived from our existing intellectual property.

We also invest in the discovery of new Fc domain technologies and antibody product candidates to expand our intellectual property portfolio.

Our worldwide patent estate includes issued patents and pending patent applications with claims directed to XmAb Fc domains, our clinical- and preclinical-stage product candidates, and our computational protein design methods and platforms.

The patent expiration dates or projected patent expiration dates for pending patent applications in the United States and major foreign jurisdictions for our key technologies and drug candidates are set forth below.

We also have pending patent applications that, if granted, may extend the exclusivity of certain technologies and products.

Technology Patent or Projected Patent Expiry*

Cytotoxic 2025 U.S.

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CD28 T-Cell Engagers

Company Products Patent Expiry

XmAb808 2041 U.S, and Ex-U.S.

Company Products Patent or Projected Patent Expiry*

XmAb808 2041 U.S.

Partnered Products Patent Expiry

XmAb819 2040 U.S.

Partnered Products Patent or Projected Patent Expiry*

Ultomiris 2028 U.S.

Sotrovimab 2025 U.S.;

The Hatch-Waxman Act permits a patent term extension for FDA-approved drugs, including biological products, of up to five years beyond the expiration of the patent.

The length of the patent term extension is related to the length of time the drug is under regulatory review.

Patent extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval, and only one patent applicable to an approved drug may be extended.

Similar provisions are available in Europe and other jurisdictions to extend the term of a patent that covers an approved drug.

In the future, if and when our pharmaceutical product candidates receive FDA approval, we expect to apply for patent term extensions on patents covering those products.

We intend to seek patent term extensions to any of our issued patents in any jurisdiction where these are available;

however, there is no guarantee that the applicable authorities, including the FDA in the United States, will agree with our assessment of whether such extensions should be granted, and even if granted, the length of such extensions.

The Patient Protection and Affordable Care Act, as amended by the Healthcare and Education Affordability Reconciliation Act (collectively the ACA) created a regulatory scheme authorizing the FDA to approve biosimilars via an abbreviated licensure pathway.

In many cases, this allows biosimilars to be brought to market without conducting the full suite of clinical trials typically required of originators.

Under the ACA, a manufacturer may submit an application for licensure of a biologic product that is "biosimilar to" or "interchangeable with" a previously approved biological product or "reference product." The "biosimilar" application must include specific information demonstrating biosimilarity based on data derived from:

(1) analytical studies, (2) animal studies, and (3) a clinical study or studies that are sufficient to demonstrate safety, purity, and potency in one or more appropriate conditions of use for which the reference product is licensed, except that FDA may waive some of these requirements for a given application.

Under this new statutory scheme, an application for a biosimilar product may not be submitted to the FDA until four years after the date of first licensure.

The FDA may not approve a biosimilar product until 12 years from the date on which the reference product was first licensed.

The law does not change the duration of patents granted on biological products.

Even if a product is considered to be a reference product eligible for exclusivity, another company could market a competing version of that product if the FDA approves a full Biologics License Application (BLA) for such 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.

There have been recent proposals to repeal or modify the ACA, and it is uncertain how any of those proposals, if approved, would affect these provisions.

In addition to patent protection, we rely on trade secret protection and know-how to expand our proprietary position around our technology and other discoveries and inventions that we consider important to our business.

We seek to protect this intellectual property in part by entering into confidentiality agreements with our employees, consultants, scientific advisors, clinical investigators, and other contractors and also by requiring our employees, commercial contractors, and certain consultants and investigators, to enter into invention assignment agreements that grant us ownership of certain discoveries or inventions made by them.

Further, we seek trademark protection in the United States and in certain other jurisdictions where available and when we deem appropriate.

We have obtained registrations for the Xencor trademark, as well as certain other trademarks, which we use in connection with our pharmaceutical research and development services and our clinical-stage products, including XmAb.

We currently have registrations for Xencor and XmAb in the United States, Australia, Canada, the

European Union, the United Kingdom, and Japan, and for Proteins by Design in the United States, Australia, Canada, and the European Union and the United Kingdom.

patent expiry includes any patent term adjustment and/or patent term extension;

patent expiry may be subject to further extension via supplementary protection certificates.

Under the Hatch-Waxman Act, patent term extensions may be available for FDA-approved drugs, including biological products, for up to five years beyond the expiration of a patent.

The length of any extension is generally based on the duration of regulatory review, subject to a maximum remaining patent term of 14 years from the date of product approval, and only one patent per approved product may be extended.

Similar patent term extension mechanisms exist in Europe and other jurisdictions.

If and when our product candidates receive regulatory approval, we expect to seek patent term extensions where available;

however, there can be no assurance that such extensions will be granted or, if granted, of their duration.

The Patient Protection and Affordable Care Act, as amended by the Healthcare and Education Affordability Reconciliation Act (collectively, the ACA), established an abbreviated licensure pathway for biosimilar and interchangeable biological products.

Under this framework, a biosimilar application generally may not be submitted to the FDA until four years after the date of first licensure of the reference product, and the FDA may not approve a biosimilar until 12 years after such first licensure.

The ACA does not alter the duration of patent protection for biological products.

In addition, even if a product qualifies for regulatory exclusivity as a reference product, a competing product could be approved through a full Biologics License Application supported by independent preclinical and clinical data.

Legislative proposals have been introduced from time to time to modify or repeal aspects of the ACA, and it is uncertain how any such changes, if enacted, would affect these provisions.

In addition to patents, we rely on trade secrets and proprietary know-how to protect aspects of our technologies and discoveries that are not subject to patent protection.

We seek to safeguard these assets through confidentiality agreements with employees, consultants, scientific advisors, clinical investigators, and other third parties, as well as invention assignment agreements that provide us with ownership of certain discoveries and inventions.

We also pursue trademark protection in the United States and selected foreign jurisdictions where appropriate.

We hold trademark registrations for Xencor and XmAb in the United States, Australia, Canada, the European Union, the United Kingdom, and Japan, and for Proteins by Design in the United States, Australia, Canada, the European Union, and the United Kingdom.

Third-Party Vendors and Suppliers

Our internal research activities are focused on early research stage and preclinical activities and studies.

We rely on third-party vendors, suppliers and contractors for all other research, development and clinical activities.

We are able to internally manufacture the quantities of our product candidates required for relatively short preclinical animal studies.

We believe that this allows us to accelerate the drug development process by not relying on third parties for all of our manufacturing needs.

We have adopted a manufacturing strategy of contracting with third parties in accordance with current good manufacturing practices (cGMPs) for the manufacture of drug substance and product, including our pipeline of antibody development candidates.

We have used third-party manufacturers for all our antibody candidates which include XmAb819, XmAb541, XmAb808, plamotamab, XmAb942 and XmAb657.

Additional contract manufacturers are used to fill, label, package and distribute investigational drug products.

This allows us to maintain a more flexible infrastructure while focusing our expertise on developing our products.

We do not have any long-term manufacturing agreements in place and will ultimately depend on contract manufacturers for the manufacture of our products for commercial sale, as well as for process development.

KBI Biopharma, Inc.

In July 2014, we entered into a master services agreement (KBI Agreement) with KBI Biopharma, Inc.

We have engaged KBI under the KBI Agreement for process development, clinical scale-up, analytical method development, formulation development, and other services related to drug substance and drug product for our antibody development candidates, XmAb541 and plamotamab, in accordance with cGMP regulations.

For each bispecific program, we have entered into a separate agreement with the terms and conditions of services and payment.

The KBI Agreement is for a three-year term but is automatically extended on an annual basis until the services are completed.

The KBI Agreement may be terminated by either party for a breach that is not remedied within 30 days after notice or 60 days after notice of the existence of an incurable scientific or technical issue that renders KBI unable to render services under the KBI Agreement, by after 60-day notice, or in the event of a bankruptcy of a party.

For termination other than a material breach by KBI, we must pay for all services conducted prior to the termination and to wind down the activities.

Cell Line Agreements with Selexis

In December 2015, we entered into a master service agreement (Selexis Agreement) with Selexis SA (Selexis) for the manufacture of Selexis cell lines.

Under the terms of the Selexis Agreement, Selexis will manufacture cell lines for the antibody candidates provided by us and upon completion of the cell lines, we have the option to take an unrestricted commercial license to the cell line.

The terms of each commercial license require us to make payments upon achievement of certain development and regulatory milestones and we will also pay royalties based on a percentage of net sales for products that are derived from or utilize the Selexis cell line.

The royalty is less than 1%.

Selexis has manufactured cell lines for certain of our bispecific antibody drug candidates, and we currently have rights to obtain commercial licenses to the Selexis cell line for antibody candidates including XmAb819 and plamotamab.

Our internal research activities are primarily focused on early-stage research and preclinical studies.

We rely on third-party vendors, suppliers, and contractors for the majority of our research, development, manufacturing, and clinical activities.

We are able to internally manufacture limited quantities of product candidates for short-duration preclinical animal studies, which we believe allows us to accelerate certain aspects of development.

For all other manufacturing needs, we rely on third-party manufacturers operating in compliance with current good manufacturing practices (cGMPs).

We use third-party manufacturers for all of our antibody drug candidates, including XmAb819, XmAb541, XmAb808, plamotamab, XmAb942, XmAb657 and XmAb412.

Additional contract manufacturers perform fill, finish, labeling, packaging, and distribution of investigational drug products.

This outsourced manufacturing strategy allows us to maintain operational flexibility while focusing internal resources on product discovery and development.

We do not have long-term manufacturing commitments in place and expect to continue to rely on third-party manufacturers for clinical and commercial supply, as well as for process development.

Master Services Agreement with Alimentiv Inc.

In February 2025, we entered into a master services agreement with Alimentiv Inc.

for contract research organizations (“CROs”) services supporting clinical trial management and development (including site selection, study design, site monitoring, management and training, and patient selection).

The agreement includes customary termination rights and payment obligations for costs incurred and non-cancellable commitments.

Alimentiv conducts clinical study activities for our XmAb942 program.

Master Services Agreement with Kapadi (formerly OncoBay Clinical, Inc.)

In August 2023, we entered into a master services agreement with OncoBay Clinical, Inc., now known as Kapadi, for CROs services supporting clinical trial management and development (including site selection, study design, site monitoring, management and training, and patient selection).

The agreement includes customary termination rights and payment obligations for costs incurred and non-cancellable commitments.

Kapadi conducts clinical studies for our XmAb541 program.

License Agreement with BIO-TECHNE

In April 2021, we entered into an agreement with BIO-TECHNE for a non-exclusive license to a certain recombinant monoclonal antibody reactive with human CLDN6.

We are using this protein in our XmAb541 drug candidate.

Under the terms of this agreement, we made an upfront payment and are obligated to make payments upon the achievement of certain development, regulatory and sales milestones, and royalties based on a percentage of net sales from products that are derived from the CLDN6 antibody.

The royalty is less than 1%.

Umbrella Development Services Agreement with Patheon Biologics LLC

In September 2018, we entered into an Umbrella Development Services Agreement (Patheon Agreement) with Patheon Biologics LLC (Patheon).

Under the terms of the Patheon Agreement, any of the affiliates within the global network of service sites in Thermo Fisher Scientific Inc.’s Pharma Services Group may perform clinical manufacturing and development services for us in accordance with cGMP regulations.

The Patheon Agreement may be terminated by either party for a breach or default that is not remedied within 30 days, or such other time period as may be reasonably necessary

to remedy such breach after receiving notice of the breach from the non-breaching party or if the other party is subject to an insolvency event.

We have the unilateral right to terminate the Patheon Agreement upon 30 days written notice to Patheon for any business reason, subject to cancellation fees.

Patheon has the unilateral right to terminate the Patheon Agreement if we request to reschedule work beyond 120 days, if project work is not progressing according to our expectations and we cannot agree on appropriate changes, if after six months of inactivity on a project at our request or if Patheon determines it is unable to perform its obligations in a safe and effective way in compliance with applicable regulatory requirements.

Patheon manufactures drug substance material for our XmAb819 program and drug product for our plamotamab program.

In April 2021, we entered into a non-exclusive license agreement with BIO-TECHNE for a recombinant monoclonal antibody reactive with human CLDN6, which is used in our XmAb541 program.

The agreement requires an upfront payment, milestone payments upon achievement of development, regulatory, and sales milestones, and royalties of less than 1% on net sales of products derived from the licensed antibody.

Master Services Agreement with WuXi Biologics (Hong Kong) Limited

In February 2021, we entered into a Master Services Agreement (WuXi Agreement) with WuXi Biologics (Hong Kong) Limited (WuXi).

Under the terms of the WuXi Agreement, WuXi and its affiliates will perform manufacturing, analytical, development and other services for Xencor in accordance with applicable regulations.

The WuXi Agreement includes customary rights to replacement of non-conforming products.

The WuXi Agreement may be terminated by either party for a breach by the other party that is not remedied within 45 days (or 10 days for a non-payment breach), or if the other party is subject to an insolvency event.

We have the unilateral right to terminate the WuXi Agreement upon 90 days’ prior written notice to WuXi for any reason, subject to applicable cancellation fees.

WuXi has the unilateral right to terminate the WuXi Agreement only if the services cannot be performed due to technical difficulties or the performance of the services is not permitted under applicable law.

WuXi manufactures drug substance and drug product for our XmAb808, XmAb657 and XmAb942 programs.

In February 2021, we entered into a master services agreement with WuXi Biologics (Hong Kong) Limited, under which WuXi and its affiliates provide manufacturing, analytical, and development services in compliance with applicable regulations.

The agreement includes customary remedies for non-conforming products and termination rights for breach,

insolvency, or convenience, subject to notice requirements and cancellation fees.

WuXi currently manufactures drug substance and drug product for our XmAb808, XmAb657, XmAb942 and XmAb412 programs.

Master Services Agreement with Vetter Pharma International GmbH

In October 2020, we entered into a master services agreement with Vetter Pharma International GmbH for clinical scale-up, analytical method development, formulation development, and manufacturing of drug product for certain bispecific antibody candidates, including vudalimab and XmAb541.

Services are governed by separate program-specific agreements.

The agreement is for an eight-year term and renews annually, which includes customary termination provisions for breach or technical inability to perform.

Vetter Pharma International GmbH currently manufactures drug products for our XmAb819 and XmAb541 programs.

Master Clinical Services Agreement with ICON Clinical Research Limited

In April 2016, we entered into a Master Clinical Services Agreement (ICON Agreement) with ICON Clinical Research Limited (ICON) which was amended in April 2021.

Under the terms of the ICON Agreement, ICON and its affiliates will perform clinical trial services (including site selection, study design, site monitoring, management and training, and patient selection) for Xencor in accordance with applicable regulations.

The ICON Agreement may be terminated by either party for a breach by the other party that is not remedied within 30 days, or if the other party is subject to an insolvency event.

Each party may terminate the ICON Agreement upon 30 days’ prior written notice to the other party for any reason;

however, such termination would not affect any ongoing project under the ICON Agreement.

We may unilaterally terminate any project under the ICON Agreement upon 30 days’ prior written notice to ICON for any reason, subject to applicable close-out costs.

ICON provides services to us in connection with ongoing Xencor-sponsored clinical trials in oncology indications.

In April 2016, as amended in April 2021, we entered into a master clinical services agreement with ICON Clinical Research Limited for clinical trial services, including site selection, study design, monitoring, and trial management.

The agreement may be terminated by either party for breach, insolvency, or convenience, subject to notice provisions, and individual projects may be terminated separately.

ICON Clinical Research Limited provides clinical services for our Xencor-sponsored oncology trials.

Cell Line Agreements with Selexis SA

In December 2015, we entered into a master services agreement with Selexis SA for the manufacture of proprietary cell lines.

Upon completion of a cell line, we have the option to obtain an unrestricted commercial license.

These licenses require milestone payments and royalties on net sales of products derived from the cell line, with royalties of less than 1%.

Selexis SA has manufactured cell lines for certain of our bispecific antibody candidates, and we currently have rights to obtain commercial licenses for cell lines used in XmAb819 and plamotamab.

Master Services Agreement with PPD Development, L.P.

In June 2015, we entered into a Master Services Agreement (PPD Agreement) with PPD Development, L.P.(PPD).

Under the terms of the PPD Agreement, PPD will perform clinical trial management and clinical development services (including site selection, study design, site monitoring, management and training, and patient selection) for Xencor in accordance with applicable regulations.

The PPD Agreement may be terminated by either party for a breach upon 30 days' written notice, if such breach is not cured within 30 days.

We may terminate the PPD Agreement upon 30 days' written notice to PPD for any reason;

however, we will be obligated for any costs incurred through the cancellation date and any non-refundable and non-cancellable commitments incurred by PPD.

PPD conducts clinical studies for our vudalimab program.

Master Services Agreement with Vetter Pharma International GmbH

In October 2020, we entered into a master services agreement (Vetter Agreement) with Vetter Pharma International GmbH (Vetter).

We have engaged Vetter under the Vetter Agreement for clinical scale-up, analytical method development, formulation development, and other services related to manufacturing drug product for our bispecific antibody candidates, vudalimab and XmAb541, in accordance with cGMP regulations.

For each bispecific program, we have entered into a separate agreement with the terms and conditions of services and payment.

The Vetter Agreement is for an eight-year term but is automatically extended on an annual basis until the services are completed.

The Vetter Agreement

may be terminated by either party for a breach that is not remedied within 60 days after notice or 60 days after notice of the existence of an incurable scientific or technical issue that renders Vetter unable to render services under the Vetter Agreement.

For termination other than a material breach by Vetter, we must pay for all services conducted prior to the termination and to wind down the activities.

Vetter manufactures drug product for our XmAb541 program.

Master Services Agreement with Kapadi (formerly OncoBay Clinical, Inc.)

In August 2023, we entered into a Master Services Agreement (Kapadi Agreement) with OncoBay Clinical, Inc., now Kapadi.

Under the terms of the Kapadi Agreement, Kapadi will perform Contract Research Organization (CRO) services including clinical trial management and clinical development services (including site selection, study design, site monitoring, management and training, and patient selection) for Xencor in accordance with applicable regulations.

The Kapadi Agreement may be terminated by either party for a breach upon 30 days' written notice, if such breach is not cured within thirty (30) days.

We may terminate the Kapadi Agreement upon 60 days' written notice to Kapadi for any reason;

however, we will be obligated for any costs incurred through the cancellation date and any non-refundable and non-cancellable commitments incurred by Kapadi.

Kapadi conducts clinical studies for our XmAb541 program.

We compete in an industry that is characterized by rapidly advancing technologies, intense competition, and a strong emphasis on proprietary products.

Our competitors include pharmaceutical companies, biotechnology companies, academic institutions, and other research organizations.

We compete with these parties for promising targets for antibody-based therapeutics, new technology for optimizing antibodies, and in recruiting highly qualified personnel.

Many competitors and potential competitors have substantially greater scientific, research, and product development capabilities as well as greater financial, marketing and sales, and human resources than we do.

In addition, many specialized biotechnology firms have formed collaborations with large, established companies to support the research, development, and commercialization of products that may be competitive with ours.

Accordingly, our competitors may be more successful than we may be in developing, commercializing, and achieving widespread market acceptance.

In addition, our competitors’ products may be more effective, more effectively developed, or more effectively marketed and sold than any treatment we or our development partners may commercialize, which may render our product candidates obsolete or noncompetitive before we can recover the expenses related to developing and commercializing any of our product candidates.

Competition in the field of cancer and autoimmune drug development is intense, with hundreds of compounds in clinical trials.

Many large pharmaceutical companies and other smaller biotechnology companies are developing competing bispecific antibody platforms, and many of these companies have advanced multiple drug candidates into clinical development, including Amgen;

Macrogenics, Inc.;

Regeneron Pharmaceuticals, Inc.;

and Roche Holding AG.

We are developing bispecific antibody drug candidates engineered to direct cytotoxic T-cell killing of solid tumor cells, by engaging the CD3 or CD28 receptor on T cells and an antigen on tumor cells.

Other companies conducting clinical trials to evaluate CD3 or CD28 bispecific antibodies directed to antigens expressed on solid tumors include Amgen;

BioAtla, Inc.;

Context Therapeutics Inc.;

CytomX Therapeutics, Inc.;

Immunocore Holdings plc;

Janux Therapeutics, Inc.;

Johnson & Johnson;

Regeneron Pharmaceuticals, Inc.;

Roche Holding AG;

Takeda Pharmaceutical Co.

Other antibodies, antibody drug conjugates and cell therapies are in development or approved to treat patients with cancer.

We are also developing bispecific antibody drug candidates engineered to direct cytotoxic T-cell killing of B cells, by engaging the CD3 receptor on T cells and either the CD20 or CD19 receptor on B cells.

Other companies currently conducting clinical trials to evaluate CD3 bispecific antibodies directed to CD20 or CD19 for the treatment of autoimmune disease include Amgen;

Cullinan Therapeutics, Inc.;

and Roche Holding AG.

Other antibodies and cell therapies are in development or approved to treat patients with autoimmune diseases.

We are developing antibody drug candidates that target the cytokine TL1A for the potential treatment of IBD.

Other companies currently conducting clinical trials to evaluate anti-TL1A antibodies include:

Merck & Co., Inc;

Roche Holding AG;

Spyre Therapeutics, Inc.;

and Teva Pharmaceutical Industries Limited.

In addition, we are aware of a number of other companies with development-stage programs that may compete with the drug candidates we and our licensees are developing in the future.

We anticipate that we will face intense and increasing competition as new treatments enter the market and advanced technologies become available.

In June 2015, we entered into a master services agreement with PPD Development, L.P.

for clinical trial management and development services (including site selection, study design, site monitoring, management and training, and patient selection).

The agreement includes customary termination rights and requires us to pay costs incurred through termination and certain non-cancellable commitments.

PPD Development, L.P.

conducts clinical studies for our vudalimab program.

Master Service Agreement with KBI Biopharma, Inc.

In July 2014, we entered into a master services agreement with KBI Biopharma, Inc.

for process development, clinical scale-up, analytical method development, formulation development, and related drug substance and drug product services for certain antibody candidates, including XmAb541 and plamotamab.

Services and payment terms for each program are governed by separate statements of work.

The agreement renews annually unless terminated and may be terminated by either party for uncured breach, specified technical issues, or insolvency.

Upon termination other than for material breach by KBI Biopharma, Inc., we are required to pay for services performed and wind-down costs.

Master Service Agreement with PAREXEL International, LLC

We entered into a master services agreement with PAREXEL International, LLC in April 2014, as amended from time to time, most recently in April 2025, for CROs services supporting clinical trial management and development (including site selection, study design, site monitoring, management and training, and patient selection).

The agreement includes customary termination rights and payment obligations for costs incurred and non-cancellable commitments.

PAREXEL conducts clinical studies for our plamotamab program.

Regulatory Overview

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Generally, our activities in other countries will be subject to regulation that is similar in nature and scope as that imposed in the U.S., although there can be important differences.

We, along with our contract manufacturers (CMOs), contract research organizations (CROs), and third-party vendors, will be required to satisfy these requirements in each of the countries in which we wish to conduct studies or seek approval of our product candidates.

We, along with our contract manufacturing organizations (“CMOs”), CROs, and third-party vendors, will be required to satisfy these requirements in each of the countries in which we wish to conduct studies or seek approval of our product candidates.

The process of obtaining these approvals and the subsequent compliance with appropriate federal and state statutes and regulations require the expenditure of substantial time and financial resources.

Various federal and state statutes and regulation also govern or influence testing, manufacturing, safety, labeling, storage, tracking, tracing and record-keeping of drugs and biologic products and their marketing.

Various federal and state statutes and regulations also govern or influence testing, manufacturing, safety, labeling, storage, tracking, tracing and record-keeping of drugs and biologic products and their marketing.

Drug Development Process

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These products are also subject to other federal, state and local statutes and regulations.

Our product candidates are subject to regulation by the FDA as a biologic.

Our product candidates are subject to regulation by the FDA as biologics.

Biologics require the submission of a Biologics License Application (BLA) to the FDA and approval of the BLA by the FDA before marketing in the United States.

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completion of preclinical laboratory tests, animal studies, and formulation studies performed in accordance with applicable regulations, including the FDA’s current Good Laboratory Practices (GLP) regulations;

submission to and acceptance by the FDA of an IND which must become effective before human clinical trials in the United States may begin and must be updated annually;

submission to and acceptance by the FDA of an Investigational New Drug (IND) application which must become effective before human clinical trials in the United States may begin and must be updated annually;

approval by an independent institutional review board (IRB) or ethics committee representing each clinical site before each clinical trial may be initiated;

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An IND will automatically become effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns or questions related to the proposed clinical trials.

In such a case, the IND may be placed on clinical hold, and the IND sponsor and the FDA must resolve any outstanding concerns or questions before clinical trials can begin.

In such a case, the IND may be placed on a full clinical hold or partial clinical hold.

Under a full clinical hold, the IND sponsor must resolve any outstanding concerns before the clinical trial can begin.

Under a partial clinical hold, there may be a delay or suspension of only part of the clinical work requested under the IND.

Accordingly, submission of an IND may or may not result in the FDA allowing clinical trials to commence.

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A separate submission to an existing IND must also be made for each successive clinical trial to be conducted, and the FDA must grant permission, either explicitly or implicitly by not objecting, before each clinical trial can begin.

Accordingly, we cannot be sure that

submission of an IND will result in the FDA allowing clinical trials to begin, or that, once begun, issues will not arise that could cause the trial to be suspended or terminated.

Accordingly, we cannot be sure that submission of an IND will result in the FDA allowing clinical trials to begin, or that, once begun, issues will not arise that could cause the trial to be suspended or terminated.

Clinical trials involve the administration of the product candidate to human patients under the supervision of qualified investigators, generally physicians not employed by or under the clinical trial sponsor’s control, in accordance with GCPs, which include the requirement that all research subjects provide their informed consent for their participation in any clinical trial.

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When a foreign clinical trial is conducted under an IND, all FDA IND requirements must be met unless waived.

When the foreign clinical trial is not conducted under an IND, the sponsor must ensure that the study is conducted in accordance with GCP, including review and approval by an independent ethics committee (IEC) and informed consent from subjects.

When the foreign clinical trial is not conducted under an IND, the sponsor must ensure that the study is conducted in accordance with GCP, including

review and approval by an independent ethics committee (IEC) and informed consent from subjects.

The GCP requirements are intended to help ensure the protection of human subjects enrolled in non-IND foreign clinical trials, as well as the quality and integrity of the resulting data.

FDA must also be able to validate the data from the study through an on-site inspection if necessary.

There are also requirements governing the reporting of ongoing clinical trials and clinical trial results to public registries, including on clinicaltrials.gov.

There are also requirements governing the reporting of ongoing clinical trials and clinical trial results to public registries, including on ClinicaTtrials.gov.

A sponsor of an investigational biological product for a serious disease or condition is required to make available, such as by posting on its website, its policy on evaluating and responding to requests for individual patient access to such investigational biological product.

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Such post-approval trials are sometimes referred to as Phase 4 clinical trials.

In the case of drugs approved under Accelerated

Approval, post-approval trials are intended to confirm clinical benefit seen with a surrogate endpoint using a long-term clinical outcome endpoint.

In the case of drugs approved under Accelerated Approval, post-approval trials are intended to confirm clinical benefit seen with a surrogate endpoint using a long-term clinical outcome endpoint.

Failure to exhibit due diligence with regard to conducting such Phase 4 clinical trials could result in withdrawal of approval for products or other consequences.

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The results of product development, preclinical studies and clinical trials, along with descriptions of the manufacturing process, analytical tests, proposed labeling, and other relevant information are submitted to the FDA in the form of a BLA requesting approval to market the product for one or more specified indications.

Data can come from company-sponsored clinical trials intended to test the safety and effectiveness of a use of a product, or from a number of alternative sources, including trials initiated by investigators.

Data can come from company-sponsored clinical trials intended to test the safety and effectiveness of a use of a product, or from a number of

alternative sources, including trials initiated by investigators.

To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety and effectiveness of the investigational product to the satisfaction of the FDA.

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The FDA conducts its own analysis of the clinical trial data, which could result in extensive discussions between the FDA and us during the review process.

The review and evaluation of an BLA by the FDA is extensive and time-consuming and may take longer than originally planned to complete, and we may not receive a timely approval, if at all.

The review and evaluation of a BLA by the FDA is extensive and time-consuming and may take longer than originally planned to complete, and we may not receive a timely approval, if at all.

The FDA is required to refer an application for a novel biological product to an advisory committee or explain why such referral was not made.

An advisory committee is a panel of independent experts, including clinicians and other scientific experts, that reviews, evaluates and provides a recommendation as to whether the application should be approved

and under what conditions.

The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

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Product approvals may be withdrawn for non-compliance with regulatory standards or based on the results of post-market studies or surveillance programs.

Additionally, post-approval, many types of changes to the approved product, such as adding new indications, changing manufacturing processes and adding labeling claims, are subject to further testing requirements and FDA review and approval.

Additionally, post-approval, many types of changes to the approved product, such as adding new indications, changing manufacturing processes and adding labeling claims, are subject to further testing

requirements and FDA review and approval.

Such post-approval requirements can be costly and time-consuming and can affect the potential market and profitability of the product.

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As a condition of accelerated approval, the FDA will generally require the sponsor to perform adequate and well-controlled post-marketing clinical studies to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefit.

Under the Food and Drug Omnibus Reform Act of 2022 (FDORA), the FDA may require, as appropriate, that such trials be underway prior to approval or within a specific time period after the date of approval for a product granted accelerated

Under FDORA, the FDA has increased authority for expedited procedures to withdraw approval of a biologic or indication approved under accelerated approval if, for example, the sponsor fails to conduct the required post-marketing studies or if such studies fail to verify the predicted clinical benefit.

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Post-Approval Requirements

Any biologic products for which we or our collaborators receive FDA approvals are subject comprehensive and to continuing regulation by the FDA, including, among other things, cGMP compliance for product manufacture, record-keeping requirements, periodic reporting, reporting of adverse experiences with the product, providing the FDA with updated safety and efficacy information, product sampling and distribution requirements, tracking and tracing requirements, complying with certain electronic records and signature requirements, and complying with FDA promotion and advertising requirements, which include, among others, restrictions on direct-to-consumer advertising, promoting biologics for uses or in patient populations that are not described in the product’s approved labeling (known as “off-label use”), industry-sponsored scientific and educational activities, and promotional activities involving the internet.

Any biologic products for which we or our collaborators receive FDA approvals are subject to comprehensive and to continuing regulation by the FDA, including, among other things, cGMP compliance for product manufacture, record-keeping requirements, periodic reporting, reporting of adverse experiences with the product, providing the FDA with updated safety and efficacy information, product sampling and distribution requirements, tracking and tracing requirements, complying with certain electronic records and signature requirements, and complying with FDA promotion and advertising requirements, which include, among others, restrictions on direct-to-consumer advertising, promoting biologics for uses or in patient populations that are not described in the product’s approved labeling (known as “off-label use”), industry-sponsored scientific and educational activities, and promotional activities involving the internet.

Although physicians may prescribe legally available drugs and biologics for off-label uses, manufacturers may not market or promote such off-label uses.

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Until we establish our own cGMP manufacturing facility, we expect to continue to rely on third parties for the production of clinical quantities of our product candidates, and expect to rely in the future on third parties for the production of commercial quantities.

Future FDA and state inspections may identify compliance issues at our facilities or at the facilities of our contract manufacturers that may disrupt production, or distribution, or may require substantial resources to correct.

Future FDA and state inspections may identify compliance issues at our facilities or at

the facilities of our contract manufacturers that may disrupt production, or distribution, or may require substantial resources to correct.

In addition, discovery of previously unknown problems with a product or the failure to comply with applicable requirements may result in restrictions on a product, manufacturer or holder of an approved BLA, including withdrawal or recall of the product from the market or other voluntary, FDA-initiated or judicial action that could delay or prohibit further marketing.

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FDA has authority to require post-market studies, in certain circumstances, on reduced effectiveness of a biological product and FDA may require labeling changes related to new reduced effectiveness information.

Failure to comply with FDA requirements can subject a manufacturer to possible legal or regulatory action, such as product recalls, untitled or warning letters, restrictions on the marketing or manufacturing of the product, issuance of safety alerts/ Dear Healthcare Provider letters / press releases / or other communications containing warnings or other safety information about the product, suspension of manufacturing, imposition of clinical holds on ongoing clinical trials, refusal of FDA to approve pending BLAs or supplements to approved BLAs, product seizure or detention, refusal to permit import or export of product, injunctive action, mandated corrective advertising or communications with healthcare professionals, fines, possible civil or criminal penalties, consent decrees, corporate integrity agreements, debarment, or exclusion from federal healthcare programs, total or partial suspension of production, denial or withdrawal of product approvals or refusal to allow a firm to enter into supply contracts, including government contracts, or other negative

consequences, including adverse publicity.

In addition, even if a firm complies with FDA and other requirements, new information regarding the safety or efficacy of a product could lead the FDA to modify or withdraw product approval.

Prohibitions or restrictions on sales or withdrawal of future products marketed by us could materially affect our business in an adverse way.

Changes in regulations, statutes or the interpretation of existing regulations could impact our business in the future by requiring, for example:

(i) changes to our manufacturing arrangements;

(ii) additions or modifications to product labeling;

(iii) the recall or discontinuation of our products;

or (iv) additional record-keeping requirements.

If any such changes were to be imposed, they could adversely affect the operation of our business.

Patent Term Restoration and Marketing Exclusivity

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Third-party payors are increasingly challenging the prices charged, examining the medical necessity, and reviewing the cost-effectiveness of medical products and services and imposing controls to manage costs.

Third-party payors may limit coverage to specific products on an approved list, also known as a formulary, which might not include all of the approved products for a particular indication.

Third-party payors may limit

coverage to specific products on an approved list, also known as a formulary, which might not include all of the approved products for a particular indication.

In order to secure coverage and reimbursement for any drug product candidate that might be approved for sale, we may need to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of the drug product candidate, in addition to the costs required to obtain FDA or other comparable regulatory approvals.

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Anti-Kickback, False Claims, and Other Healthcare Laws and Compliance Requirements

In the United States, the research, manufacturing, distribution, sale and promotion of drug products and medical devices are potentially subject to regulation by various federal, state and local authorities in addition to the FDA, including the Centers for Medicare & Medicaid Services (CMS), other divisions of Health and Human Services (e.g., the Office of Inspector General), the U.S.

Inspector General), the U.S.

Department of Justice, the Federal Trade Commission, the Drug Enforcement Administration, the Consumer Product Safety Commission, the Environmental Protection Agency, the Occupational Safety and Health Administration, state Attorneys General, and other state and local government agencies.

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Violations of this law are punishable by up to ten years in prison, criminal fines, administrative civil money penalties and exclusion from participation in federal healthcare programs.

While this Statute has a number of exceptions and regulatory safe harbors that safeguard certain common, industry practices from prosecution, these exceptions and safe harbors are narrowly defined, and parties must satisfy all elements of an available exception or safe harbor to avoid

Further, a person or entity does not need to have actual knowledge of these statutes or specific intent to violate them to have committed a violation.

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Although we would not submit claims directly to payors, biopharmaceutical companies can be held liable under these laws if they are deemed to “cause” the submission of false or fraudulent claims by, for example, providing inaccurate billing or coding information or promoting a product off-label.

Penalties for a federal False Claims Act violation include three times the actual damages sustained by the government, plus mandatory civil penalties effective as of January 15, 2025 of between $14,308 and $28,619 for each separate false claim (each of which is subject to adjustment for inflation) and the potential for exclusion from participation in federal healthcare programs.

Penalties for a federal False Claims Act violation include civil penalties for each separate false claim and the potential for exclusion from participation in federal healthcare programs.

Although the federal False Claims Act is a civil statute, conduct that results in a federal False Claims Act violation may also implicate various federal criminal statutes, such as the federal Anti-Kickback Statute described above.

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HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act (HITECH) and their implementing regulations, also imposes requirements relating to the privacy, security and transmission of protected health information on HIPAA covered entities, which include certain healthcare providers, health plans and healthcare clearinghouses, and their business associates who conduct certain activities for or on their behalf involving protected health information on their behalf.

Entities that are found to be in violation of HIPAA as the result of a breach of unsecured protected health information, a complaint about privacy practices or an audit by Health and Human Services may be subject to significant civil, criminal and administrative fines and penalties and/or additional reporting and oversight obligations if required to enter into a

resolution agreement and corrective action plan with HHS to settle allegations of HIPAA non-compliance.

Further, entities that knowingly receive individually identifiable health information from a HIPAA-covered entity in a manner that is not authorized or permitted by HIPAA may be subject to criminal penalties.

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The failure to comply with these laws and regulatory requirements subjects companies to possible legal or regulatory action.

As discussed above, depending on the circumstances, failure to meet applicable laws and regulatory requirements can result in criminal prosecution, fines or other penalties, injunctions, recall or seizure of products, total or partial suspension of production, denial or withdrawal of product approvals or refusal to allow a company to enter into supply contracts, including government contracts.

As discussed above, depending on the circumstances, failure to meet applicable laws and regulatory requirements can result in criminal prosecution, fines or other penalties or damages, disgorgement, reputational harm, diminished profits or future earnings, exclusion of products from government-funded healthcare programs, such as Medicare or Medicaid, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our financial results.

Ensuring business arrangements comply with applicable laws, as well as responding to possible investigations by government authorities can be time- and resource-consuming, and can divert a company’s attention from the business.

Europe / Rest of World Government Regulation

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Our website address is www.xencor.com.

Our website and the information contained on, or that can be accessed through, the website will not be deemed to be incorporated by reference in and are not considered part of this Annual Report.

Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to reports filed or furnished pursuant to Section 13(a) and 15(d) of the Exchange Act are available free of charge on the Investor Relations portion of our website at www.xencor.com as soon as reasonably practical after we electronically file such material with, or furnish it to, the Securities and Exchange Commission (SEC).

The SEC maintains an internet site at www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC.

The information contained on, or accessible through, our website is not incorporated by reference into, and does not form a part of, this Annual Report on Form 10-K.

Our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) and 15(d) of the Securities Exchange Act of 1934 are available free of charge on the Investor Relations portion of our website as soon as reasonably practical after we electronically file such material with, or furnish it to, the Securities and Exchange

Commission (SEC).

The SEC maintains an internet website at www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC.

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