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Item 7. Management’s Discussion and Analysis

2023-03-30 compared with 2022-03-23 · 186 added, 140 removed, 163 unchanged (67% of the section changed)

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We undertake no obligation to update any forward-looking statements in the discussion of our financial condition and results of operations to reflect events or circumstances after the date of this report or to reflect actual outcomes.

Mustang Bio, Inc.

(“Mustang,” “We,” “Us” or the “Company”) is a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for hematologic cancers, solid tumors and rare genetic diseases.

Mustang is a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for hematologic cancers, solid tumors and rare genetic diseases.

We aim to acquire rights to these technologies by licensing or otherwise acquiring an ownership interest in the technologies, funding their research and development and eventually either out-licensing or bringing the technologies to market.

Our pipeline is currently focused in three core areas:

gene therapies for rare genetic disorders, chimeric antigen receptor (“CAR”) engineered T cell (“CAR T”) therapies for hematologic malignancies and CAR T therapies for solid tumors.

CAR T therapies for hematologic malignancies, CAR T therapies for solid tumors and gene therapies for rare genetic disorders.

For each therapy we have partnered with world class research institutions.

For our CAR T therapies we have partnered with COH, Fred Hutch, Nationwide and Mayo Clinic.

For our gene therapies, we have partnered with St.

Jude Children’s Research Hospital (“St.

Jude”) in the development of a first-in-class ex vivo lentiviral treatment of X-linked severe combined immunodeficiency (“XSCID”) and with Leiden University Medical Centre (“LUMC”) for RAG1 severe combined immunodeficiency (“RAG1-SCID”).

For our CAR T therapies we have partnered with the City of Hope National Medical Center (“COH”), Fred Hutchinson Cancer Research Center (“Fred Hutch”), Nationwide Children’s Hospital (“Nationwide”) and the Mayo Foundation for Medical Education and Research (“Mayo Clinic”).

Gene Therapies

In partnership with St.

Jude, our XSCID gene therapy programs (MB-107 and MB-207) are being conducted under an exclusive license to develop a potentially curative treatment for XSCID, a rare genetic immune system condition in which affected patients do not live beyond infancy without treatment.

This first-in-class ex vivo lentiviral gene therapy is currently in two Phase 1/2 clinical trials involving two different autologous cell products:

a multicenter trial of the MB-107 product in newly diagnosed infants sponsored by St.

Jude and a single-center trial of the MB-207 product in previously transplanted patients sponsored by the National Institutes of Health (“NIH”).

In January 2021 we received approval to proceed with our Investigational New Drug (“IND”) application with the U.S.

Food and Drug Administration (“FDA”) to initiate a pivotal non-randomized multicenter Phase 2 clinical trial of MB-107 in newly diagnosed infants with XSCID who are under the age of two.

We expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial in the second half of 2022.

In January 2022, the FDA issued a hold, pending Chemistry, Manufacturing and Controls (“CMC”) clearance, on our IND application to conduct a pivotal non-randomized multicenter Phase 2 clinical trial of MB-207 in previously transplanted XSCID patients.

In order to lift this hold and receive FDA clearance for the IND, we believe the most critical activities will be to (1) perform process validation manufacturing runs using healthy donor material and (2) ensure qualification of all assays related to the product release.

We estimate that these activities will take 3-6 months to complete, and we therefore expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial in the first quarter of 2023.

Jude in the development of a first-in-class ex vivo lentiviral treatment of XSCID and with LUMC in the development of a first-in-class ex vivo lentiviral treatment of RAG1-SCID.

The Company expects to incur substantial expenses for the foreseeable future relating to research, development and commercialization of its potential products.

However, there can be no assurance that the Company will be successful in securing additional resources when needed, on terms acceptable to the Company, if at all.

Therefore, there exists substantial doubt about the Company’s ability to continue as a going concern.

The consolidated financial statements do not include any adjustments related to the recoverability of assets that might be necessary despite this uncertainty.

CAR T Therapies

Our pipeline of CAR T therapies is being developed under exclusive licenses from several world class research institutions.

Our strategy is to license these technologies, support preclinical and clinical research activities by our partners and transfer the underlying technology to our cell processing facility located in Worcester, Massachusetts, in order to conduct our own clinical trials.

Our strategy is to license these technologies, support preclinical and clinical research activities by our academic partners and transfer the underlying technology to our cell processing facility located in Worcester, Massachusetts, in order to conduct our own clinical trials.

We are developing CAR T therapies for hematologic malignancies in partnership with COH targeting CD123 (MB-102) and CS1 (MB-104) and with Fred Hutch targeting CD20 (MB-106).

Phase 1 clinical trials sponsored by COH for MB-102 and MB-104 and by Fred Hutch for MB-106 are underway.

In the third quarter of 2019 the FDA approved our IND application to initiate a multi-center Phase 1/2 clinical trial of MB-102, and our clinical trial began enrollment in 2020 for the treatment of patients with blastic plasmacytoid dendritic cell neoplasm.

In May 2021, the FDA approved our IND application to initiate a multi-center Phase 1/2 clinical trial of MB-106, and we expect to begin the treatment of patients with non-Hodgkin lymphoma and chronic lymphocytic leukemia in the first half of 2022.

In December 2022, we announced that the safety review team (SRT), after thoroughly reviewing the safety data from Dose Level 1 (100 x 10 6 CAR T cells), unanimously recommended dose escalation to Dose Level 2 (300 x 10 6 CAR T cells).

We anticipate initiation of the Does Level 2 cohort in 2023.

In May 2021, we announced that the FDA had approved our IND application allowing for initiation of a multi-center Phase 1/2 clinical study of MB-106 in patients with relapsed or refractory B cell NHL or CLL (Clinicaltrials.gov Identifier:

NCT05360238).

We plan to file an IND for a multicenter Phase 1/2 trial for MB-104 for the treatment of patients with multiple myeloma once COH has established a safe and effective dose.

We are also developing CAR T therapies for solid tumors in partnership with COH targeting IL13Rα2 (MB-101), HER2 (MB-103) and PSCA (MB-105).

In addition, we have partnered with Nationwide for the C134 oncolytic virus (MB-108) in order to enhance the activity of MB-101 for the treatment of patients with glioblastoma multiforme (“GBM”).

In addition, we have partnered with Nationwide for the C134 oncolytic virus (MB-108) in order to enhance the activity of MB-101 for the treatment of patients with glioblastoma (“GBM”).

Phase 1 clinical trials sponsored by COH for MB-101, MB-103 and MB-105 are underway.

A Phase 1 clinical trial sponsored by the University of Alabama at Birmingham (“UAB”) for MB-108 began during the third quarter of 2019 and, in the second half of 2022, we plan to file an IND for the combination of MB-101 and MB-108 – which is referred to as MB-109 – for the treatment of patients with relapsed or refractory GBM and anaplastic astrocytoma.

We also plan to file INDs and initiate our own clinical trials for MB-103 for the treatment of patients with metastatic breast cancer to brain and for MB-105 for the treatment of patients with prostate and pancreatic cancer.

A Phase 1 clinical trial sponsored by UAB for MB-108 began during the third quarter of 2019.

In the first half of 2023, we plan to file an IND for the combination of MB-101 and MB-108 – which is referred to as MB-109 – for the treatment of patients with relapsed or refractory GBM and anaplastic astrocytoma.

The Company is also collaborating with the Mayo Clinic to develop a novel technology that may be able to transform the administration of CAR T therapies and potentially be used as an off-the-shelf therapy.

Mustang plans to file an IND application for a multicenter Phase 1 clinical trial once a lead construct has been identified.

Gene Therapies

In partnership with St.

This first-in-class ex vivo lentiviral gene therapy has been evaluated in two Phase 1/2 clinical trials involving two different autologous cell products:

an ongoing multicenter trial of the MB-107 product in newly diagnosed infants sponsored by St.

Jude and a single-center trial of the MB-207 product in previously transplanted patients sponsored by the NIH.

In January 2021 we received approval to proceed with our IND application with the FDA to initiate a pivotal non-randomized multicenter Phase 2 clinical trial of MB-107 in newly diagnosed infants with XSCID who are under the age of two.

We expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial in 2023.

Our IND for MB-207 was submitted to the FDA in December 2021.

In January 2022, the FDA issued a clinical hold, pending CMC data.

In order to lift this clinical hold and receive a safe-to-proceed from the FDA for the IND, we believe the most critical activities will be to (1) perform process validation manufacturing runs using healthy donor material and (2) ensure qualification of all assays related to the product release.

Following completion of these activities and the earliest release of the clinical hold, we expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial 2023.

Recent Events

Leiden University Medical Centre License

On November 10, 2021, the Company announced that it has executed an exclusive license agreement with Leiden University Medical Centre (“LUMC”) for a first-in-class ex vivo lentiviral gene therapy for the treatment of RAG1 severe combined immunodeficiency (“RAG1-SCID”).

The therapy, which includes low-dose conditioning prior to reinfusion of the patients’ own gene-modified blood stem cells, is currently being evaluated in a Phase 1/2 multicenter clinical trial in Europe.

The ongoing clinical trial recently enrolled its first patient, and additional clinical sites are expected to be added in the near future.

The RAG1-SCID program has been granted Orphan Drug Designation by the European Medicines Agency.

The Company also established an ongoing partnership with Frank J.

Staal, Ph.D., professor of Molecular Stem Cell Biology and molecular immunologist at LUMC, whose laboratory developed the therapy.

Staal will continue the development of additional lentiviral gene therapies in his lab, to which we have rights under the agreement.

The RAG1-SCID therapy expands the pipeline of ex vivo lentiviral gene therapies we are currently developing.

The lead programs, MB-107 and MB-207, are being investigated for the treatment of XSCID.

A pivotal multicenter trial studying MB-107 is expected to enroll its first patient in the first quarter of 2022.

Combined, XSCID and RAG1-SCID make up almost 60% of all SCID cases combined.

MB-102 (CD123 CAR T Cell Program for BPDCN, AML and High-Risk MDS)

The Company anticipates initiation of the Dose Level 2 cohort in 2023.

MB-106 (CD20-targeted CAR T for Non-Hodgkin Lymphoma and Chronic Lymphocytic Leukemia)

On November 4, 2021, the Company announced that interim Phase 1/2 data on MB-106 have been selected for a poster presentation at the 63rd American Society of Hematology Annual Meeting (“ASH2021”), which was held from December 11-14, 2021.

The abstract posted on the ASH2021 website reported on 16 patients [12 follicular lymphoma (FL), 2 mantle cell lymphoma (MCL), 1 CLL and 1 diffuse large B-cell lymphoma (DLBCL)] treated following a major cell manufacturing process modification.

CAR T cells are administered at one of 4 dose levels (DL):

3.3x105, DL2:

3.3x106, DL4:

1x107 CAR T cells/kg.

All DLs were reached, with no dose-limiting toxicities observed to date.

The overall response rate (ORR) was 94% (15/16) with a complete response (CR) rate of 62% (10/16).

In patients with FL (n=12), ORR was 92% (11/12) and CR rate was 75% (9/12).

Among patients with FL who received DL 3 or 4, the CR rate was 86%.

The patient with CLL had a PET-negative CR and undetectable measurable residual disease in peripheral blood and bone marrow by flow cytometry at a sensitivity of 10-4 (uMRD4) on day 28.

The patient with DLBCL achieved a partial response (PR) on day 28, and a repeat PET on day ~90 showed deepening of the PR.

Among patients who achieved a CR, only one patient with FL relapsed after 9 months.

All other CRs are ongoing (range:

3-18 months).

CAR T persistence was lost at day 95 in one patient who had progression and proceeded to other anti-lymphoma treatment;

2 other patients lost CAR T engraftment by day 181 and 201 with B-cell recovery.

All other patients continue to have detectable CAR T cells as of last follow-up (maximum of 13 months post-infusion).

Among the 16 total patients reported in the abstract, there were seven occurrences of cytokine release syndrome (4 patients with Grade 1 and 3 patients with Grade 2) and one occurrence of Grade 2 immune effector cell-associated neurotoxicity syndrome.

One patient with CLL developed Grade 3 temporary neuropathic pain which, in the absence of other explanation, was attributed to CAR T therapy.

No patients had tumor lysis syndrome or Grade 3-4 infections.

Thrombocytopenia (Grade 3-4:

19%) and neutropenia (Grade 3-4:

94%) were common, but there were no bleeding complications, and the rate of febrile neutropenia was 19%.

NIH Grant For MB-106 CD20-Targeted CAR T Cell Therapy

On November 1, 2021, we announced that the Company was awarded a grant of approximately $2 million from the National Cancer Institute.

This two-year grant will partially fund the Phase 1, Open Label, Multicenter Trial to Assess the Safety, Tolerability and Efficacy of MB-106, a CD20-targeted, autologous CAR T cell therapy for patients with relapsed or refractory NHL or CLL.

Mayo Clinic License

In August 2021, we announced an exclusive license agreement with the Mayo Foundation for Medical Education and Research (the “Mayo Clinic”) for a novel technology that may be able to transform the administration of CAR T therapies and has the potential to be used as an off-the-shelf therapy.

The technology, developed by Larry R.

Pease, Ph.D., principal investigator and former director of the Center for Immunology and Immune Therapies at Mayo Clinic, is a new platform to administer CAR T therapy using a two-step approach.

First, a peptide is administered to the patient to drive the proliferation of the patient’s resident T cells.

This is followed by the administration of a viral CAR construct directly into the lymph nodes of the patient.

In turn, the viral construct infects the activated T cells and effectively forms CAR T cells in vivo in the patient.

Successful implementation may lead to an off-the-shelf product with no need to isolate and expand patient T cells ex vivo .

Preclinical proof-of-concept has been established, and the ongoing development of this technology will take place at Mayo Clinic.

Mustang plans to file an Investigational New Drug (“IND”) application for a multicenter Phase 1 clinical trial once a lead construct has been identified.

NCT05360238).

The phase 1 portion of the trial will enroll patients in 3 separate arms, with dose escalation planned to establish a recommended phase 2 dose for each arm:

Aggressive non-Hodgkin lymphoma, with a starting dose of 1 x 106 CAR T cells/kg

Indolent non-Hodgkin lymphoma, with a starting dose of 3.3 x 106 CAR T cells/kg

Chronic lymphocytic leukemia/small cell lymphoma, with a starting dose of 1 x 106 CAR T cells/kg

The FDA deferred approval of the phase 2 portion of this trial pending review of the results of each of the 3 phase 1 arms.

Initially we are considering conducting non-randomized phase 2 registration trials in each of the following indications:

Diffuse large B cell lymphoma relapsed from CD19-directed CAR T therapy

Relapsed/refractory Waldenstrom macroglobulinemia

Relapsed/refractory chronic lymphocytic leukemia/small cell lymphoma

In April 2022, we announced that interim Phase 1/2 data on MB-106 were presented at the 2022 Tandem Meetings | Transplantation & Cellular Therapy Meetings of the American Society of Transplantation and Cellular Therapy and Center for International Blood & Marrow Transplant Research.

Data demonstrated high efficacy and a very favorable safety profile in all patients (n=25).

Five dose levels were used

during the study, and complete responses were observed at all dose levels.

Durable responses were observed in a wide range of hematologic malignancies including follicular lymphoma (“FL”), CLL, diffuse large B-cell lymphoma (“DLBCL”) and Waldenstrom macroglobulinemia (“WM”).

An ORR of 96% and a complete response (“CR”) rate of 72% were observed in all patients across all dose levels.

Also in April 2022, MB-106 data focused on CLL were presented at the 4th International Workshop on CAR-T and Immunotherapies.

In June 2022, we announced that MB-106 data were presented in an oral session at the European Hematology Association 2022 Hybrid Congress.

Mazyar Shadman of Fred Hutch presented updated interim data from the ongoing Phase 1/2 clinical trial for B-NHL and CLL.

Data presented include a 94% ORR and 78% CR rate in patients with FL.

Overall, for the 26 patients treated on the trial, there was a 96% ORR and 73% CR, including complete responses in both DLBCL patients, both WM patients, and both patients previously treated with CD19-targeted CAR-T therapy (1 DLBCL patient and 1 FL patient).

Also in June 2022, we announced that the FDA granted Orphan Drug Designation to MB-106 for the treatment of CD20+ Waldenstrom macroglobulinemia.

In October 2022, we announced that the first patient was treated in Mustang’s multicenter, open-label, non-randomized Phase 1/2 clinical trial evaluating the safety and efficacy of MB-106.

Also in October 2022, the Company provided an update on the ongoing Phase 1/2 investigator-sponsored clinical trial at Fred Hutch.

Interim Data from 28 patients treated at Fred Hutch, all with the optimized manufacturing process, continue to support MB-106 as a viable CAR-T cell therapy for B-NHLs and CLL.

As of September 2022, the interim data show:

● An overall response rate of 96% and complete response (“CR”) rate of 75% in a wide range of hematologic malignancies including follicular lymphoma (“FL”), CLL, diffuse large B-cell lymphoma, and Waldenstrom macroglobulinemia.

● Twelve patients have experienced CR for more than 12 months (10 ongoing);

four patients have experienced CR for more than two years, and the longest patient with CR is at 33 months.

● Six patients with partial response (“PR”) at their initial 28-day assessments improved to CR, and all remain in ongoing CR.

● All three patients previously treated with CD19 CAR-T cell therapy have responded to treatment with MB-106.

● A favorable safety profile for MB-106 as an outpatient therapy remains with no cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS) ≥ Grade 3.

● None of the FL patients experienced ICANS of any Grade.

In December 2022, we announced that six patients had been enrolled in Mustang’s multicenter Phase 1/2 clinical trial, with five patients infused at the starting dose levels of their respective protocol arms.

We have since treated the first WM in the indolent lymphoma arm of the trial, and we expect to provide first safety and efficacy data from that arm in the second quarter of 2023, with a more substantial data set from all 3 arms in the fourth quarter of 2023.

Finally, we anticipate that the indication for the first pivotal Phase 2 trial will be relapsed/refractory WM, with the first patient treated on that trial in the first quarter of 2024.

In Vivo CAR T Platform Technology

In December 2022 we announced that published proof-of-concept data from murine tumor model studies are anticipated in 2023.

MB-107 and MB-207 (Ex vivo Lentiviral Therapy for X-linked Severe Combined Immunodeficiency (XSCID))

In August 2021, we announced that the European Medicines Agency (“EMA”) granted Priority Medicines (“PRIME”) designation to MB-107, a lentiviral gene therapy for the treatment of XSCID in newly diagnosed infants.

In addition to PRIME designation, the EMA granted Advanced Therapy Medicinal Product (“ATMP”) classification to MB-107 in April 2020 and Orphan Drug designation in November 2020.

MB-107 has also received Orphan Drug, Rare Pediatric Disease and Regenerative Medicine Advanced Therapy (“RMAT”) designations from the U.S.

Food and Drug Administration (“FDA”).

The FDA grants Rare Pediatric Disease Designation for serious and life-threatening diseases that primarily affect children ages 18 years or younger and affect fewer than 200,000 people in the United States.

If Mustang’s BLA for MB-107 is approved, the Company may be eligible to receive a priority review voucher, which can be redeemed to obtain priority review for any subsequent marketing application and may be sold or transferred.

This program is intended to encourage development of new drugs and biologics for the prevention and treatment of rare pediatric diseases.

The FDA has also granted Rare Pediatric Disease Designation for MB-207.

If Mustang’s BLA for MB-207 is approved, the Company may be eligible to receive a priority review voucher for this product as well, which can also be redeemed to obtain priority review for any subsequent marketing application and may be sold or transferred.

MB-207 has also received Orphan Drug designation from the FDA and has received Orphan Drug designation and ATMP classification from the EMA.

Interim Phase 1/2 data on treatment of newly diagnosed infants under the age of two with the same LV vector used in MB-107 were updated at an oral presentation at the American Society of Gene & Cell Therapy (“ASGCT”) 25 th Annual Meeting held from May 16-19, 2022.

The data included 23 infants with XSCID treated with the LV vector at a median age of 3 months (range:

2 months to 14 months) with a median follow-up of 2.4 years (range:

1.4 months to 5.4 years), making it the largest known cohort of infants treated with LV gene therapy with the longest follow-up.

Transduced autologous bone marrow CD34+ cells were generated for all patients with a median vector copy number (VCN) of 0.81/cell (range:

0.16-1.81), and a median CD34+ cell dose of 9.61x10 6 /kg (range 4.40-18.95).

Prior to the infusion of cells, patients received busulfan targeted to a cumulative area-under-the-curve (cAUC) of 22 mg*hr/L.

Severe adverse events occurred in three patients (two patients with pancytopenia and hemolytic anemia, and one patient with delayed neutrophil engraftment, and all resolved.

Seventeen of 18 patients with a follow-up of > 6 months achieved robust immune reconstitution [median CD3+ 2,545/µL, CD4+ 1,568/µL, CD4+/CCR7+/CD45R0- 1,416/µL].

In these 17 patients, T cells matured appropriately as assessed by normal T cell receptor excision circles (TRECs) and TCRvβ repertoire diversity and were functional as judged by phytohemagglutinin activation (“PHA”).

All were alive with

stable vector marking in all cell lineages.

In addition, 15 patients had discontinued intravenous immunoglobulin, and 12 patients had been successfully immunized.

No evidence of clonal expansion or malignant transformation was observed.

The MB-107 timeline has been extended due to unanticipated issues related to the materials used in manufacturing.

These issues were communicated to the FDA and the Company received a written response on August 26, 2022.

The FDA response provided additional direction enabling us to continue to work effectively with our outside suppliers.

We are working towards enrolling the first patient in a pivotal multicenter Phase 2 clinical trial under our IND in 2023.

As a result of the study stopping rules, the NIH single-center trial of the MB-207 product in previously transplanted patients was suspended in 2022 due to the presence of clonal expansion in the myeloid lineage in 10% of the treated patients, although to date there have been no observations of insertional mutagenesis or malignancies.

All patients continue to be followed and remain clinically stable with no significant hematological anomalies.

Upon review of these data, the FDA agreed that the risk-benefit ratio of both MB-107 and MB-207 remains favorable to support moving forward with Mustang-sponsored multicenter clinical trials once Mustang has appropriately addressed other items flagged by the Agency.

The IND for MB-207 was submitted to the FDA in December 2021.

In January 2022, the FDA issued a clinical hold, pending additional CMC data.

In order to lift this clinical hold and receive an FDA safe-to-procced for the IND, we believe the most critical activities will be to (1) perform process validation manufacturing runs using healthy donor material and (2) ensure qualification of all assays related to the product release.

Following completion of these activities and the earliest release of the clinical hold by FDA, we expect to enroll the first patient in a pivotal multicenter Phase 2 clinical trial in 2023.

On July 27, 2022, the Company announced that the first patient successfully received LV-RAG1 ex vivo lentiviral gene therapy to treat RAG1-SCID, in an ongoing Phase 1/2 multicenter clinical trial taking place in Europe at LUMC.

The patient was administered LV-RAG1 without any complications.

LV-RAG1 allowed the patient’s body to create a functioning immune system, and he responded well to the standard vaccinations for newborns.

The same lentiviral vector drug substance produced by LUMC will be used to transduce patients’ cells to create the MB-110 drug product produced at Mustang Bio’s Worcester, MA, cell processing facility for further clinical development and to facilitate eventual commercial launch of the product.

Registration Statements

On October 23, 2020, the Company filed a shelf registration statement No.

333-249657 on Form S-3 (the “2020 S-3”), which was declared effective on December 4, 2020.

Under the 2020 S-3, the Company may sell up to a total of $100.0 million of its securities.

As of December 31, 2022, approximately $8.0 million of the 2020 S-3 remained available for sales of securities.

On April 23, 2021, the Company filed a shelf registration statement No.

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As of December 31, 2022, there have been no sales of securities under the 2021 S-3.

On October 23, 2020, the Company filed a shelf registration statement No.

333-249657 on Form S-3 (the “2020 S-3”), which was declared effective on December 4, 2020.

Under the 2020 S-3, the Company may sell up to a total of $100.0 million of its securities.

As of December 31, 2021, approximately $14.6 million of the 2020 S-3 remains available for sales of securities.

On March 29, 2019 (the “Closing Date”), the Company entered into a $20.0 million Loan Agreement with Horizon (the “Loan Agreement”), the proceeds of which were used to provide the Company with additional working capital to continue development of its gene and cell therapies.

In accordance with the Loan Agreement, $15.0 million of the $20.0 million loan was funded on the Closing Date, with the remaining $5.0 million fundable upon the Company achieving certain predetermined milestones.

On September 30, 2020, the Company repaid in full all amounts that were outstanding under the Loan Agreement.

The amount of securities we are able to sell pursuant to the registration statements on Form S-3 is limited.

See “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources.”

On March 4, 2022 (the “Closing Date”), the Company entered into a $75.0 million long-term debt facility with Runway Growth Finance Corp.

(the “Term Loan”).

Under the Term Loan, $30.0 million of the $75.0 million loan was funded on the Closing Date, with the remaining $45.0 million fundable if the Company achieves certain predetermined milestones.

The Term Loan matures on April 15, 2027 (the “Maturity Date”).

As of March 15, 2022, the Company began making monthly payments of interest only until April 1, 2024 (the “Amortization Date”).

The Amortization Date may be extended to April 1, 2025, if the Company achieves certain predetermined milestones based on equity raises and the initiation of certain clinical trials.

After that, the Company will make monthly payments of interest and principal.

If the Amortization Date is extended to April 1, 2025, the monthly payments will be recalculated in equal amounts according to the remaining number of payment dates through the Maturity Date.

All unpaid outstanding principal and accrued and unpaid interest will be due and payable in full on the Maturity Date.

The Term Loan accrues interest at a variable annual rate equal to 8.75% plus the greater of (i) 0.50% and (ii) the three month LIBOR Rate for U.S.

dollar deposits or the rate otherwise reasonably determined by the Lender to be the rate at which U.S.

dollar deposits with a term of three months would be offered by banks in London, England to major banks in the London or other offshore interbank market (the “Applicable Rate”);

provided that the Applicable Rate will not be less than 9.25%.

On December 7, 2022, the Company entered into the First Amendment (the “First Amendment”) to the Loan Agreement by and between the Company and Runway.

The First Amendment amended certain definitions and other provisions of the Loan Agreement to replace LIBOR-based benchmark rates applicable to loans outstanding under the Loan Agreement with SOFR-based rates, subject to adjustments as specified in the First Amendment.

The Applicable Rate at December 31, 2022, was 13.40%.

For the year ended December 31, 2022, the Company made interest payments of $2.7 million recorded in interest expense in the Statements of Operations.

Pursuant to the terms of the Term Loan on the Closing Date the Company paid the Lender upfront fees out of proceeds of $0.4 million consisting of a 1% commitment fee and a deposit of $75,000.

In addition, the Company paid other cash fees directly to third parties comprising of an advisory fee and legal fees totaling $2.3 million.

Also, in connection with the Term Loan, on March 4, 2022, the Company issued a warrant to the Lender to purchase 748,036 shares of the Company’s common stock with an exercise price of $0.8021 (the “Warrant”) via a warrant agreement (the “Warrant Agreement”).

The Warrant is exercisable for ten years from the date of issuance.

The Lender may exercise the Warrant with cash or through a net issuance conversion.

The shares of the Company’s common stock will be registered at the Company’s first opportunity after the date of the exercise of the Warrant.

In addition, the provisions of the Warrant Agreement provide for additional warrants to be issued upon funding of the term loan tranches.

The fair value of the warrant at the grant date was determined utilizing a Black Scholes Model with the following assumptions:

risk free rate of return 1.74%, volatility of 57.3%, 10-year life yielding a value of approximately $0.4 million as of March 4, 2022.

The fair value of the warrant was also recorded in debt discount and will be amortized over the life of the Term Loan.

At-the-Market Offering

On July 13, 2018, the Company filed a shelf registration statement No.

333-226175 on Form S-3, as amended on July 20, 2018 (the “2018 S-3”), which was declared effective in August 2018.

Under the 2018 S-3, the Company may sell up to a total of $75.0 million of its securities.

In connection with the 2018 S-3, the Company entered into an At-the-Market Issuance Sales Agreement (the “ATM Agreement”) with B.

In July 2018, the Company entered into an At-the-Market Issuance Sales Agreement (the “Mustang ATM”) with B.

Riley Securities, Inc.

Riley FBR, Inc.), Cantor Fitzgerald & Co., National Securities Corporation, and Oppenheimer & Co.

(each an “Agent” and collectively, the “Agents”), relating to the sale of shares of common stock.

Under the ATM Agreement, the Company pays the Agents a commission rate of up to 3.0% of the gross proceeds from the sale of any shares of common stock.

On December 31, 2020, the ATM Agreement was amended to add H.C.

Riley FBR, Inc.), Cantor Fitzgerald & Co., National Securities Corporation (now B.

Riley FBR, Inc.), and Oppenheimer & Co.

(each an “Agent” and collectively, the “Agents”), relating to the sale of shares of common stock pursuant to the 2020 S-3.

Under the Mustang ATM, the Company pays the Agents a commission rate of up to 3.0% of the gross proceeds from the sale of any shares of common stock.

On December 31, 2020, the Mustang ATM was amended to add H.C.

Wainwright & Co., LLC as an Agent.

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In connection with these sales, we paid aggregate fees of approximately $1.3 million for net proceeds of approximately $70.6 million.

Pursuant to the Founders Agreement, the Company issued 196,952 shares of common stock to Fortress at a weighted average price of $0.84 per share for the year ended December 31, 2022, and recorded zero shares issuable to Fortress in connection with the shares issued under the Mustang ATM.

Pursuant to the Founders Agreement, Mustang issued 576,157 shares of common stock to Fortress at a weighted average price of $3.70 per share for the year ended December 31, 2021, in connection with the shares issued under the Mustang ATM.

The amount of securities we are able to sell pursuant to the registration statements on Form S-3 is limited.

See “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Liquidity and Capital Resources.”

Authorized Shares

On June 21, 2022, the stockholders of the Company voted at the 2022 Annual Meeting to approve an amendment to Mustang’s Amended and Restated Certificate of Incorporation to increase the number of shares of common stock authorized for issuance by 50 million shares, bringing the total number of authorized shares of common stock to 200 million shares.

To date, we have not received approval for the sale of our product candidates in any market and, therefore, have not generated any product sales from our product candidates.

In addition, we have incurred substantial operating losses since our inception, and expect to continue to incur significant operating losses for the foreseeable future and may never become profitable.

As of December 31, 2021, we have an accumulated deficit of $251.8 million.

We are a majority-controlled subsidiary of Fortress Biotech, Inc.

(“Fortress”).

We are a majority-controlled subsidiary of Fortress.

As a “Controlled Company” we rely on the exemption provided by Nasdaq Listing Rule 5615(c)(2), which permits us to maintain less than a majority of independent directors on our board.

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If the actual timing of the performance of services or the level of effort varies from the estimate, we adjust accrued expenses or prepaid expenses accordingly, which impact research and development expenses.

Although we do not expect our estimates to be materially different

from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period.

Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result in reporting amounts that are too high or too low in any particular period.

Fair Value Measurement

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Under the accounting guidance, fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability.

As such, fair value is a

market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability.

The accounting guidance requires fair value measurements be classified and disclosed in one of the following three categories:

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ASC 740 also provides guidance on de-recognition, classification, interest and penalties, accounting in interim period, disclosure and transition.

Based on the Company’s evaluation, it has been concluded that there are no significant uncertain tax positions

requiring recognition in the Company’s financial statements.

The 2018 through 2020 tax years are the only periods subject to examination upon filing of appropriate tax returns.

Based on the Company’s evaluation, it has been concluded that there are no significant uncertain tax positions requiring recognition in the Company’s financial statements.

As of December 31, 2022, the earliest federal tax year open for the assessment of income taxes under the applicable statutes of limitations is its 2019 tax year.

The Company believes that its income tax positions and deductions would be sustained on audit and does not anticipate any adjustments that would result in a material change to its financial position.

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Research and development expenses primarily consist of personnel related expenses, including salaries, benefits, travel, and other related expenses, stock-based compensation, payments made to third parties for license, sponsored research and milestone costs related to in-licensed products and technology, payments made to third party contract research organizations for preclinical and clinical studies, investigative sites for clinical trials, consultants, the cost of acquiring and manufacturing clinical trial materials, costs associated with regulatory filings, laboratory costs and other supplies.

Research and development expense increased by approximately $12.6 million from $37.2 million for the year ended December 31, 2020 to $49.8 million for the year ended December 31, 2021.

Research and development expenses increased by approximately $12.6 million from $49.9 million for the year ended December 31, 2021, to $62.5 million for the year ended December 31, 2022.

The increase in research and development expense for the year ended December 31, 2022 was primarily attributable to the following:

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● $2.7 million for increased laboratory supply costs;

● $2.3 million for increased consulting costs primarily to support Mustang-sponsored clinical trials;

● approximately $3.0 million for increased other costs including third-party contract research organizations, outside services, vector manufacturing and depreciation;

● offset by approximately $1.1 million for decreased costs for sponsored research and clinical trial agreements.

● $1.7 million for increased vector manufacturing costs;

● $2.6 million for increased clinical trial related costs;

● approximately $1.6 million for increased other costs including depreciation, software licenses, assay development and rent;

● offset by approximately $0.3 million for decreased costs for consulting and sponsored research agreements.

Research and development expenses - licenses acquired decreased by $4.4 million from $5.8 million for the year ended December 31, 2021 to $1.5 million for the year ended December 31, 2022.

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● Approximately $3.1 million for the annual stock dividend to Fortress;

● $0.8 million for increased costs related to our license with Mayo Clinic;

● $0.3 million related to our LUMC license;

● $0.2 million related to our licenses with COH.

● $0.3 million related to our CD20 license with Fred Hutch;

● $0.1 million related to our CSL Behring (Calimmune);

● $0.1 million related to our LentiBOOST TM license with SIRION;

● offset by approximately $1.1 million for increased costs related to our licenses with Mayo Clinic and Leiden University Medical Centre.

We expect our research and development activities to increase as we develop our existing product candidates and potentially acquire new product candidates, reflecting increasing costs associated with the following:

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● license fees and milestone payments related to in-licensed products and technology;

● expenses incurred under agreements with contract research organizations, investigative sites and consultants that conduct our clinical trials and our preclinical activities;

● expenses incurred under agreements with CROs, investigative sites and consultants that conduct our clinical trials and our preclinical activities;

● facility expenses, which include rent, utilities and maintenance costs;

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● $0.4 million for increased general and administrative employee compensation costs due primarily to additional headcount to support the Company’s continued growth;

● $0.8 million for increased state taxes;

● $0.3 million for increased audit and accounting fees;

● $0.9 million for increased other costs, including consulting and professional fees, outside services and insurance;

● $1.3 million for increased corporate and patent related legal costs;

● $0.4 million for increased third-party consulting;

● $0.6 million for increased other costs, including outside services;

● offset by approximately $1.3 million for decreased stock-based costs;

● $0.2 million decrease in state taxes.

We anticipate general and administrative expenses will increase in future periods, reflecting continued and increasing costs associated with:

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Other Income (Expense)

Other income (expense) consists primarily of interest income earned on cash balances and short-term investments and interest expense on the Company’s notes payable.

For the year ended December 31, 2021 and 2020, total other income (expense) were approximately $0.4 million of income and $3.2 million of expense, respectively.

The $3.6 million increase in other income (expense) for the year ended December 31, 2021 was primarily attributable to lower interest expense of $3.9 million partially offset by lower interest income of $0.3 million.

Other income (expense) consists primarily of funds received from the NIH grant, interest income earned on cash balances and short-term investments and interest expense on the Company’s notes payable.

For the year ended December 31, 2022, and 2021, total other income (expense) was approximately $1.4 million of expense and $0.4 million of income, respectively.

The $1.7 million decrease in other income (expense) for the year ended December 31, 2022 was primarily attributable to increased interest expense of $3.3 million partially offset by $1.3 million of grant income and increased interest income of $0.3 million.

We expect interest expense to remain higher so long as the Term Loan is outstanding.

The amount of our interest expense may increase if interest rates continue to increase because the Term Loan has a variable rate of interest.

Liquidity and Capital Resources

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As of December 31, 2022, the Company had an accumulated deficit of $329.4 million.

The Company has funded its operations to date primarily through the sale of equity, its Loan Agreement with Runway and its venture debt financing agreement (the "Horizon Loan Agreement") with Horizon Technology Finance Corporation ("Horizon"), herein referred to as the "Horizon Notes."

In September 2020, we repaid the Horizon Notes in full all amounts that were outstanding under the Horizon Loan Agreement, which was comprised of $15.0 million face value of the outstanding notes, $112,500 accrued and unpaid interest, a $750,000 loan termination fee and prepayment penalties of $550,000.

The Company has funded its operations to date primarily through the sale of equity and its Term Loan.

The Company expects to continue to use the proceeds from previous financing transactions primarily for general corporate purposes, including financing the Company’s growth, developing new or existing product candidates, and funding capital expenditures, acquisitions and investments .

The Company currently anticipates that its cash and cash equivalents balances at December 31, 2021, are sufficient to fund its anticipated operating cash requirements for at least one year from the date of this Form 10-K.

From January 1, 2022 through March 18, 2022, the Company issued approximately 2.4 million shares of common stock at an average price of $0.99 per share for gross proceeds of $2.4 million under the ATM Agreement.

The Company will be required to expend significant funds in order to advance the development of its product candidates.

The Company will require additional financings through equity and debt offerings, collaborations and licensing arrangements or other sources to fully develop, prepare regulatory filings, obtain regulatory approvals and commercialize its existing and any new product candidates.

If the Company is unable to arrange for such financings, or unable to arrange for them on terms acceptable to the Company, the Company’s current development plans and plans for expansion of its facility and general and administrative infrastructure will be curtailed.

The continuation of our business as a going concern is dependent upon raising additional capital and eventually attaining and maintaining profitable operations.

As of December 31, 2022, there is substantial doubt about the Company’s ability to continue as a going concern for the next 12 months from the date of issuance of these financial statements.

The financial statements included in this Annual Report on Form 10-K do not include any adjustments that might be necessary should operations discontinue.

As of the date of this Annual Report on Form 10-K, our public float was less than $75 million.

As a result, we will be limited by the baby shelf rules until such time as our public float exceeds $75 million, which means we only have the capacity to sell shares up to one-third of our public float under shelf registration statements in any twelve-month period.

If our public float decreases, the amount of securities we may sell under our Form S-3 shelf registration statements will also decrease.

We will remain constrained by the baby shelf rules under our Form S-3 registration statements until such time as our public float exceeds $75 million, at which time the amount of securities we may sell under a Form S-3 registration statement will no longer be limited by the baby shelf rules.

Contractual Obligations

We enter into contracts in the normal course of business with licensors, CROs, contract manufacturing organizations (CMOs) and other third parties for the procurement of various products and services, including without limitation biopharmaceutical development, biologic assay development, commercialization, clinical and preclinical development, clinical trials management, pharmacovigilance and manufacturing and supply.

These contracts typically do not contain minimum purchase commitments (although they may) and are generally terminable by us upon written notice.

Payments due upon termination or cancelation/delay consist of payments for services provided or expenses incurred, including non-cancelable obligations of our service providers, up to the date of cancellation;

in certain cases, our contractual arrangements with CROs and CMOs include cancelation and/or delay fees and penalties.

Cash Flows for the Years Ended December 31, 2022 and 2021

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Net cash used in operating activities was $65.1 million for the year ended December 31, 2022, compared to $53.7 million for the year ended December 31, 2021.

Net cash used in operating activities for the year ended December 31, 2022, was primarily due to approximately $77.5 million in net loss, partially offset by $4.0 million change in operating assets and liabilities, $2.7 million of depreciation expense, $2.3 million of non-cash stock compensation expenses, $1.1 million of common shares issuable for the Founders Agreement, $0.7 million equity fee to Fortress related to the Term Loan, $0.5 million of amortization of debt discount, $0.4 million of research and development-licenses acquired, $0.2 million loss on disposal of property and equipment, $0.3 million of amortization of operating lease right-of-use assets, and $0.2 million of equity fee on issuance of common shares to Fortress.

Net cash used in operating activities was $53.7 million for the year ended December 31, 2021, compared to $37.3 million for the year ended December 31, 2020.

Net cash used in operating activities for the year ended December 31, 2021, was primarily due to approximately $66.4 million in net loss, partially offset by $4.2 million of common shares issuable for Founders shares, $3.3 million of non-cash stock compensation expenses, $2.2 million of depreciation expense, $1.9 million of equity fee on issuance of common shares to Fortress and $1.6 million of research and development-licenses acquired .

Net cash used in operating activities for the year ended December 31, 2020, was primarily due to approximately $60.0 million in net loss, partially offset by $7.6 million of common shares issuable for Founders shares, $3.1 million change in operating assets and liabilities, $3.0 million of non-cash stock compensation expenses, $2.5 million of research and development-licenses acquired, $2.4 million of equity fee on issuance of common shares to Fortress, $2.3 million of accretion of debt discount and $1.7 million of depreciation expense.

Investing Activities

Net cash used in investing activities was $3.0 million for the year ended December 31, 2022, representing $2.7 million in purchases of fixed assets and $0.4 million in purchases of research and development licenses, offset by $0.1 million of proceeds from the sale of fixed assets.

Net cash used in investing activities was $5.4 million for the year ended December 31, 2021, representing $4.0 million in purchases of fixed assets and $1.4 million in purchases of research and development licenses.

Net cash provided by investing activities was $4.4 million for the year ended December 31, 2020, representing $2.5 million in purchases of research and development licenses and $1.9 million in purchases of fixed assets.

Financing Activities

Net cash provided by financing activities was $34.1 million during the year ended December 31, 2022, driven by (i) proceeds from the issuance of the Term Loan of $30.0 million, net of financing costs of $2.7 million;

(ii) gross proceeds of $6.6 million, net of offering costs of $0.1 million, from the Mustang ATM;

and (iii) $0.2 million raised from the issuance of the Company’s common shares in connection with the Employee Stock Purchase Plan (“ESPP”) .

Net cash provided by financing activities was $70.8 million during the year ended December 31, 2021, representing gross proceeds of $71.9 million, net of offering costs of $1.4 million, from the Mustang ATM and $0.3 million raised from the issuance of the Company’s common shares in connection with the ESPP.

Net cash provided by financing activities was $78.1 million during the year ended December 31, 2020, representing gross proceeds of $59.8 million, net of offering costs of $1.1 million, from the Mustang ATM;

gross proceeds of $37.2 million, net of offering costs of $2.4 million, from our June 2020 underwritten public offering and $0.3 million raised from the issuance of the Company’s common shares in connection with the ESPP, partially offset by the prepayment of the Horizon Notes of $15.7 million.

Quantitative and Qualitative Disclosures About Market Risks

Not applicable.

Financial Statements and Supplementary Data.

The information required by this Item is set forth in the financial statements and notes thereto beginning at page F-1 of this Annual Report on Form 10-K.

Changes in and Disagreements with Accountants on Accounting and Financial Disclosure.

Not applicable.

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 7. Management’s Discussion and Analysis