Asfiled with the Securities and Exchange Commission on July 19, 2024. 

Registration Statement No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Mustang Bio, Inc.

(Exact name of registrant as specified in itscharter)

377 Plantation Street

Worcester, Massachusetts 01605

(781) 652-4500

(Address, including zip code, and telephonenumber, including area code, of registrant’s principal executive offices)

Manuel Litchman, M.D.

President and Chief Executive Officer

377 Plantation Street

Worcester, Massachusetts 01605

(781) 652-4500

(Name, address, including zip code, and telephonenumber,

including area code, of agent for service)

Copies to:

Rakesh Gopalan

JosephWalsh 

TroutmanPepper Hamilton Sanders LLP 

301S. College Street, 34th Floor 

Charlotte,NC 28202 

(704)998-4050 

Approximatedate of commencement of proposed sale to the public: From time to time after this registration statement becomes effective.

Ifany of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under theSecurities Act of 1933 check the following box:  x

Ifthis Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check thefollowing box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.¨

Ifthis Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the SecuritiesAct registration statement number of the earlier effective registration statement for the same offering. ¨

Ifthis Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the SecuritiesAct registration statement number of the earlier effective registration statement for the same offering. ¨

Indicate by check mark whether the registrantis a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company.See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,”and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Ifan emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complyingwith any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ¨

The Registrant hereby amends this registrationstatement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment whichspecifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the SecuritiesAct or until this registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuantto said Section 8(a), may determine.

The information in this preliminaryprospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securitiesand Exchange Commission is effective. This preliminary prospectus is not an offer to sell these securities and is not soliciting an offerto buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECTTO COMPLETION, DATED JULY 19, 2024 

PRELIMINARY PROSPECTUS

6,497,800Shares of Common Stock

This prospectus relates to the resale by the sellingstockholders (the “Selling Stockholders”) identified in this prospectus under the section “The Selling Stockholders,”of up to 6,497,800 shares of our common stock, par value $0.0001 per share, issuable uponthe exercise of certain warrants held by the Selling Stockholders (including shares that may be issued to the holder in lieu of fractionalshares). We are registering the offer and sale of common stock on behalf of the Selling Stockholders to satisfy certain registration rightsthat we have granted to the Selling Stockholders.

The Selling Stockholders may resell or disposeof the common stock, or interests therein, at fixed prices, at prevailing market prices at the time of sale or at prices negotiated withpurchasers, to or through underwriters, broker-dealers, agents, or through any other means described in the section of this prospectustitled “Plan of Distribution.” The Selling Stockholders will bear commissions and discounts, if any, attributable tothe sale or disposition of the common stock, or interests therein, held by the Selling Stockholders. We will bear all costs, expensesand fees in connection with the registration of the offer and sale of the common stock under the Securities Act of 1933, as amended (the “Securities Act”). We will not receive any of the proceeds from the sale of the common stock by the Selling Stockholders.

Our common stock is listed on the NasdaqCapital Market under the symbol “MBIO.” On July 18, 2024, the last reported sale price of our common stock was $0.3400per share. You are urged to obtain current market quotations for our common stock.

Investing in our securities involves risks.You should review carefully the risks and uncertainties described under the heading “Risk Factors” contained in thisprospectus and under similar headings in the other documents that are incorporated by reference into this prospectus, as described onpage 19 of this prospectus.

Neither the Securities and Exchange Commission(the “SEC”) nor any state securities commission has approved or disapproved of these securities or passed upon the accuracyor adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Thedate of this prospectus is                      , 2024. 

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus provides youwith a general description of the common stock that may be resold by the Selling Stockholders. In certain circumstances, we may providea prospectus supplement that will contain specific information about the terms of a particular offering by the Selling Stockholders. Wealso may provide a prospectus supplement to add information to, or update or change information contained in, this prospectus. To theextent there is a conflict between the information contained in this prospectus and any prospectus supplement, you should rely on theinformation in the prospectus supplement, provided that if any statement in one of these documents is inconsistent with a statement inanother document having a later date — for example, a document incorporated by reference in this prospectus or anyprospectus supplement — the statement in the later-dated document modifies or supersedes the earlier statement.

This prospectus and the documentsincorporated by reference into this prospectus include important information about us, the securities being offered and other informationyou should know before investing in our securities. You should not assume that the information contained in this prospectus is accurateon any date subsequent to the date set forth on the front cover of this prospectus or that any information we have incorporated by referenceis correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus is delivered or securitiesare sold or otherwise disposed of on a later date. It is important for you to read and consider all information contained in this prospectus,including the documents incorporated by reference therein, in making your investment decision. You should also read and consider the informationin the documents to which we have referred you under “Where You Can Find More Information” and “Incorporationof Certain Information by Reference” in this prospectus.

We have not authorized anyoneto give any information or to make any representation to you other than those contained or incorporated by reference in this prospectus.We take no responsibility for, and can provide no assurances as the reliability of, any other information that others may give to you.This prospectus does not constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any personto whom it is unlawful to make such offer or solicitation in such jurisdiction.

Forinvestors outside the United States: we have not done anything that would permit this offering or possession or distributionof this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside theUnited States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, theoffering of our securities and the distribution of this prospectus outside the United States.

This prospectus contains summariesof certain provisions contained in some of the documents described herein, but reference is made to the actual documents for completeinformation. All of the summaries are qualified in their entirety by the actual documents. Copies of the documents referred to hereinhave been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectusis a part, and you may obtain copies of those documents as described in this prospectus under “Where You Can Find More Information.”

PROSPECTUS SUMMARY

This summary highlightsselected information from this prospectus and does not contain all of the information that may be important to you in making an investmentdecision. This summary is qualified in its entirety by the more detailed information included elsewhere in this prospectus and/or thedocuments incorporated by reference herein. Before making your investment decision with respect to our securities, you should carefullyread this entire prospectus, including the information in our filings with the SEC incorporated by reference into this prospectus.

References in this prospectusto the “Company,” “we,” “us,” “our” and similar words refer to Mustang Bio, Inc.

Our Business

Overview and Product Candidate Development

We are a clinical-stage biopharmaceuticalcompany focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for hematologic cancersand solid tumors. 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 currentlyfocused in two core areas: CAR T therapies for hematologic malignancies and CAR T therapies for solid tumors. For these therapies we havepartnered with world class research institutions, including the City of Hope National Medical Center (“COH” or “Cityof Hope”), Fred Hutchinson Cancer Center (“Fred Hutch”), and Nationwide Children’s Hospital (“Nationwide”).

CAR T Therapies

Our pipeline of CAR T therapiesis 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 or our contract manufacturer’scell processing facility in order to conduct our own clinical trials.

We are developing CAR T therapyfor hematologic malignancies in partnership with Fred Hutch targeting CD20 (MB-106). In May 2021, we announced that the U.S. Food andDrug Administration (“FDA”) accepted our Investigational New Drug (“IND”) Application for MB-106. As of December2023, approximately 40 patients have been treated in an ongoing phase 1 clinical trial sponsored by Fred Hutch (ClinicalTrials.gov Identifier:NCT03277729), and approximately 20 patients have been treated in an ongoing phase 1 clinical trial sponsored by us (ClinicalTrials.govIdentifier: NCT05360238). In 2023, we received Safety Review Committee approval to continue dose escalation in all three active arms ofthe ongoing Mustang-sponsored phase 1 trial. We presented the latest results, demonstrating a favorable safety profile, complete responserate, and durability, from the ongoing Mustang-sponsored phase 1 trial at the 2023 American Society of Hematology (“ASH”)Annual Meeting. As of December 31, 2023, the MB-106 Mustang-sponsored phase 1 trial is pending one patient to complete the final doselevel required to advance to phase 2 pivotal studies for treatment of patients with relapsed or refractory indolent B-cell non-Hodgkinlymphoma.

We are also developing CART therapy for solid tumors in partnership with COH targeting IL13Rα2 (MB-101). In addition, we have partnered with Nationwide fora herpes simplex virus type 1 (“HSV-1”) oncolytic virus (MB-108) in order to enhance the activity of MB-101 for the treatmentof patients with high-grade malignant brain tumors. The Phase 1 clinical trial sponsored by COH for MB-101 (ClinicalTrials.gov Identifier:NCT02208362) has completed the treatment phase and patients continue to be assessed for long-term safety. A Phase 1 clinical trial sponsoredby the University of Alabama at Birmingham (“UAB”) for MB-108 (ClinicalTrials.gov Identifier: NCT03657576) began during thethird quarter of 2019. In October 2023, we announced that the FDA accepted our IND application for the combination of MB-101 and MB-108 – which is referred to as MB-109 – for the treatment of patients with IL13Rα2+ relapsed or refractory glioblastoma (“GBM”)and high-grade astrocytoma.

On May 18, 2023, we announceda series of changes resulting from a review of our portfolio of product candidates to determine the future strategy of our programs andthe proper allocation of our resources. Following this review, we determined to discontinue development of our MB-102 (CD123), MB-103(HER2), MB-104 (CS1) and MB-105 (PSCA) programs, all of which were CAR T therapies being developed in partnership with City of Hope.

TerminatedProduct Candidates (Gene Therapies and in vivo CAR-T)

We formerly developed severalgene therapy product candidates, which included MB-117 and MB-217 (based on technologies licensed from St. Jude Children’s ResearchHospital (“St. Jude”)) and MB-110 (based on technologies licensed from Leiden University Medical Centre (“LUMC”)).In April 2024, we entered into a termination and release agreement with St. Jude, pursuant to which we agreed to terminate the licenseagreement underpinning the MB-117 and MB-217 product candidates in exchange for a mutual release of liability and forgiveness by St. Judeof all amounts previously owing to them. Also in April 2024, we delivered a termination notice to LUMC pursuant to which we terminatedthe license agreement underpinning the MB-110 product candidate; we are currently in discussions with LUMC regarding the terms that willgovern such termination. In June 2024, we also agreed with Mayo Foundation for Medical Educationand Research (“Mayo Clinic”) to terminate the license agreement underpinning our (now former) preclinical in vivo CAR-Tprogram, together with a related sponsored research agreement, in exchange for a mutual release of liability and forgiveness by Mayo Clinicof all amounts previously owed to them.

To date, we have not receivedapproval for the sale of any of our product candidates in any market and, therefore, have not generated any product sales from our productcandidates. In addition, we have incurred substantial operating losses since our inception, and expect to continue to incur significantoperating losses for the foreseeable future and may never become profitable. As of March 31, 2024, we had an accumulated deficit of $386.2million.

TherapeuticPipeline 

Therapiesfor Oncology and Hematologic Malignancies 

MB – 106: CD20 CAR T for B cell non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) 

We believe CD20 is a promisingtarget for immunotherapy of B-cell malignancies. CD20 is a B-cell lineage-specific phosphoprotein that is expressed in high, homogeneousdensity on the surface of more than 95% of B-cell NHL and CLL. CD20 is stable on the cell surface with minimal shedding, internalization,or modulation upon antibody binding and is present at only nanomolar levels as a soluble antigen. It is well established as an effectiveimmunotherapy target, with extensive studies demonstrating improved tumor responses and survival of B-NHL patients treated with rituximaband other anti-CD20 antibodies. Importantly, CD20 continues to be expressed on the lymphoma cells of most patients with relapsed B-NHLdespite repetitive rituximab treatments, and loss of CD20 expression is not a major contributor to treatment resistance. Thus, there isstrong rationale for testing CD20 CAR T cells as an immunotherapy for NHL.

More than 80,000 new casesof NHL are diagnosed each year in the United States, and over 20,000 patients die of this group of diseases annually. Most forms of NHL,including follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, lymphoplasmacytic lymphoma, and small lymphocytic lymphoma(“SLL”), which account collectively for approximately 45% of all cases of NHL, are incurable with available therapies, exceptfor allogenic stem cell transplant (“allo-SCT”). However, many NHL patients are not suitable candidates for allo-SCT, andthis treatment is also limited by significant rates of morbidity and mortality due to graft-versus-host disease. Aggressive B-cell lymphomassuch as diffuse large B-cell lymphoma, the most common subtype of lymphoma, account for an additional 30-35% of NHL. The majority of patientswith aggressive B-NHL are successfully treated with combination chemotherapy, but a significant proportion relapse or have refractorydisease, and the outcome of these patients is poor. Innovative new treatments are therefore urgently needed.

Chronic lymphocytic leukemia/smalllymphocytic lymphoma (CLL/SLL) is a mature B cell neoplasm characterized by a progressive accumulation of monoclonal B lymphocytes. CLLis considered to be identical (i.e., one disease with different manifestations) to the NHL SLL. The malignant cells seen in CLL and SLLhave identical pathologic and immunophenotypic features. The term CLL is used when the disease manifests primarily in the blood, whereasthe term SLL is used when involvement is primarily nodal.

CLLis the most common leukemia in adults in Western countries, accounting for approximately 25 to 35 percent of all leukemias in the UnitedStates. An estimated 20,700 new cases of CLL will be diagnosed in the United States in 2024. CLL is considered to be mainly a diseaseafflicting older adults, with a median age at diagnosis of approximately 70 years; however, it is not unusual to make this diagnosis inyounger individuals (e.g., from approximately 30 to 39 years of age). The incidence increases rapidly with increasing age. The naturalhistory of CLL is extremely variable, with survival times from initial diagnosis that range from approximately 2 to 20 years, and a mediansurvival of approximately 10 years. 

Mostpatients will have a complete or partial response to initial therapy. However, conventional therapy for CLL is not curative and most patientsexperience relapse. In addition, many patients will require a change in therapy due to intolerance. Since patients with CLL are generallyelderly with a median age older than 70 years, and due to the relatively benign course of the disease in the majority of patients, onlyselected patients are candidates for intensive treatments such as allo-SCT. Innovative new treatments with a favorable safety profileare therefore urgently needed for patients with relapsed and refractory disease.

Under their IND, Fred Hutchis currently conducting a Phase 1/2 clinical study to evaluate the anti-tumor activity and safety of administering CD20-directed third-generationCAR T cells incorporating both 4-1BB and CD28 co-stimulatory signaling domains (MB-106) to patients with relapsed or refractory B-cellNHL or CLL (ClinicalTrials.gov Identifier: NCT03277729). Secondary endpoints of this study include safety and toxicity, preliminary antitumoractivity as measured by overall response rate and complete remission rate, progression-free survival, and overall survival. The studyis also assessing CAR T cell persistence and the potential immunogenicity of the cells. Finally, this study was designed so that, togetherwith Fred Hutch, we could determine a recommended Phase 2 dose. Fred Hutch intends to enroll approximately 50 subjects in this study,which is being led by the Principal Investigator Mazyar Shadman, M.D., M.P.H., Associate Professor of Fred Hutch’s Clinical ResearchDivision.

The Fred Hutch IND was amendedin 2019 to incorporate an optimized manufacturing process that had been developed in collaboration with us.

In May 2021, we announcedthat the FDA issued a safe to proceed letter for our IND application allowing for initiation of a multi-center Phase 1/2 clinical studyof MB-106 in patients with relapsed or refractory B cell NHL or CLL (Clinicaltrials.gov Identifier: NCT05360238). In August 2022, thefirst patient was treated in our study.

In November 2021, Mustangwas awarded a grant of approximately $2.0 million from NCI of the National Institutes of Health. This two-year award partially fundedthe Mustang-sponsored multicenter trial to assess the safety, tolerability and efficacy of MB-106. In August 2023, we fully utilized thegrant.

In June 2022, MB-106 receivedOrphan Drug Designation for the treatment of Waldenstrom macroglobulinemia (“WM”).

In December 2023, we presentedpreliminary clinical data for the indolent lymphoma patients treated in the ongoing Mustang-sponsored multicenter Phase 1/2 clinical studyat the American Society of Hematology (ASH) annual meeting. All 9 patients responded clinically to treatment; the observed overall responserate was 100%. All 5 follicular lymphoma patients achieved a complete response. Among the WM patients 1 patient attained a very good partialresponse, and 2 patients attained a partial response. The single patient with a hairy cell leukemia variant experienced stable disease.The safety profile demonstrated that MB-106 was well tolerated with no occurrences of cytokine release syndrome (“CRS”) abovegrade 1, and no immune effector cell-associated neurotoxicity syndrome (“ICANS”) of any grade was reported. Cell expansionand persistence were also demonstrated.

In the first quarter of 2024,we completed a successful End-of-Phase 1 meeting with the FDA regarding a potential pivotal Phase 2 single-arm clinical trial for thetreatment of WM. Per the discussions, the FDA agreed with the proposed overall design of the pivotal trial for WM at the recommended doseof 1 x 10⁷ CAR-T cells/kg and requested only minimal modifications to the study protocol. No additional nonclinical studiesare expected prior to Phase 2 or a Biologics License Application (“BLA”) filing. Due to limited resources, and as a resultof the reduction in work force described below, we have suspended patient accrual and follow-up activities under the ongoing Phase 1 trialand do not expect to initiate our pivotal Phase 2 single-arm clinical trial of MB-106 for the treatment of WM trial in 2024. Subject toavailable funds, we intend to rely on third party service providers to conduct study and manufacturing services to advance our prioritypotential product candidates.

Also in the first quarterof 2024, we completed enrollment of the indolent lymphoma arm in our multicenter Phase 1 trial. The tenth and final patient enrolled wasa patient with follicular lymphoma (FL) who achieved a complete response following treatment with 1 x 10⁷ CAR-T cells/kg. Asa result, the overall complete response rate for FL in the Phase 1 portion of this trial was sustained at 100% (N=6), with no occurrenceof CRS above grade 1 and no ICANS of any grade, despite not using prophylactic tocilizumab or dexamethasone.

In March 2024, we announcedplans to collaborate with Fred Hutch for a proof-of-concept Phase 1 investigator-sponsored clinical trial evaluating MB-106 in autoimmunediseases.

In March 2024, we were grantedthe Regenerative Medicine Advanced Therapy (“RMAT”) designation by the FDA for the treatment of relapsed or refractory CD20positive WM and FL, based on potential improvement in response as seen in clinical data-to-date. Drugs eligible for RMAT designation arethose intended to treat, modify, reverse or cure a serious or life-threatening disease or condition, and that present preliminary clinicalevidence indicating the drug has the potential to address unmet medical needs for such disease or condition. RMAT designation providesregenerative medicine advanced therapy products with the same benefits to expedite the development and review of a marketing applicationthat are available to drugs that receive Breakthrough Therapy Designation. These advantages include timely advice and interactive communicationswith FDA, as well as proactive and collaborative involvement by senior FDA managers and experienced review and regulatory health projectmanagement staff. A product designated as an RMAT also may be eligible for other FDA-expedited programs, such as Priority Review. TheFDA also may conduct a rolling review of products in its expedited programs, reviewing portions of a marketing application before thecomplete application is submitted.

MB-109:Combination MB-101 (IL13Rα2 CAR T Cell Program for Glioblastoma) and MB-108 (HSV-1 oncolytic virus C134) as a Potential Treatmentfor IL13Rα2+ Relapsed or Refractory Glioblastoma (GBM) and High-Grade Astrocytoma 

An attractive novel approachto control glioblastoma is adoptive cellular immunotherapy utilizing CAR T cells. CAR T cells can be engineered to recognize very specificantigenically distinct tumor populations and to migrate through the brain parenchyma to kill malignant cells. In addition, oncolytic viruses(“OVs”) have been developed to effectively infect and kill cancer cells in the tumor, as well as modify the microenvironmentto increase tumor immunogenicity and immune cell trafficking within the tumor. Due to these properties, OVs have been studied in combinationwith other treatments to enhance the effectiveness of immunotherapies.

Preliminary anti-tumor activityhas been observed in clinical studies administering the OV (MB-108) and CAR T cell therapy (MB-101) as single agents; however, the combinationhas not yet been explored. To determine if the combination of both therapies will result in a synergistic effect, investigators from COHdeveloped preclinical studies in orthotopic GBM models in nude mice. Dr. Christine Brown from City of Hope presented these preclinicalstudies at the American Association for Cancer Research 2022 Annual Meeting. It was observed that co-treatment with HSV-1 OV and IL13Rα2-directedCAR-T cells resulted in no additional adverse events beyond those seen with the individual therapies, and, more notably, that pre-treatmentwith HSV-1 OV re-shaped the tumor microenvironment by increasing immune cell infiltrates and enhanced the efficacy of sub-therapeuticdoses of IL13Rα2-directed CAR-T cell therapy delivered either intraventricularly or intratumorally. These preclinical studies aimedto provide a deeper understanding of this combination approach to support the potential benefit of a combination study that will evaluateHSV-1 OV (MB-108) and IL13Rα2-directed CAR-T cells (MB-101).

InOctober 2023, we received a safe-to-proceed “approval” from the FDA for our MB-109 IND application allowing us to initiatea Phase 1, open-label, non-randomized, multicenter study of MB-109 in patients with IL13Ra2+recurrent GBM and high-grade astrocytoma. In this Phase 1 clinical study, we intend to evaluate the combination of CAR-T cells (MB-101)and the herpes simplex virus type 1 oncolytic virus (MB-108) in patients with IL13Ra2+ high-gradegliomas. The design of this study involves first a lead in cohort, wherein patients are treated with MB-101 alone without prior MB-108administration. After successful confirmation of the safety profile of MB-101 alone, the study will then investigate increasing dosesof intratumorally administered MB-108 followed by dual intratumoral (ICT) and intraventricular (ICV) administration of MB-101. Due tolimited resources, we do not currently expect to initiate this study until such time, if any, that additional resources become availableto us.

MB-101(IL13Rα2 CAR T Cell Program for Glioblastoma) 

GBM is the most common brainand central nervous system (“CNS”) cancer, accounting for approximately 49.1% of malignant primary brain and CNS tumors, approximately54% of all gliomas, and approximately 16% of all primary brain and CNS tumors. More than 14,490 new GBM cases were predicted to be diagnosedin the U.S. for 2023. Malignant brain tumors are the second leading cause of cancer-related deaths in adolescents and young adults aged15-39 and the most common cancer occurring among 15-19-year-olds in the U.S. While GBM is a rare disease with an incidence of 2-3 casesper 100,000 persons per year in the U.S. and European Union (“EU”), it is quite lethal, with five-year survival rate historicallyunder 10%, which has been virtually unchanged for decades. Standard of care therapy consists of maximal surgical resection, radiation,and chemotherapy with temozolomide, which, while rarely curative, is shown to extend median overall survival from 4.5 to 15 months. GBMremains difficult to treat due to the inherent resistance of the tumor to conventional therapies.

Immunotherapy approaches targetingbrain tumors offer promise over conventional treatments. IL13Rα2 is an attractive target for CAR T therapy, as it has limitedexpression in normal tissue but is overexpressed on the surface of greater than 50% of GBM tumors. CAR-T cells are designed to expressmembrane-tethered IL-13 receptor ligand (“IL-13”) mutated at a single site (glutamic acid at position 13 to a tyrosine; E13Y)with high affinity for IL13Rα2 and reduced binding to IL13Rα1 in order to reduce healthy tissue targeting (Kahlon KS etal. Cancer Research. 2004;64:9160-9166).

We are developing an optimizedCAR-T product incorporating enhancements in CAR-T design and T cell engineering to improve antitumor potency and T cell persistence. Theseinclude a second-generation hinge-optimized CAR containing mutations in the IgG4 linker to reduce off-target Fc interactions (JonnalagaddaM et al. Molecular Therapy. 2015;23(4):757-768.), a 4-1BB (CD137) co-stimulatory signaling domain for improved survival and maintenanceof CAR T cells, and the extracellular domain of CD19 as a selection/tracking marker. In order to further improve persistence, either centralmemory T-cells (T_CM) or enriched CD62L+ naïve and memory T cells (T_N/MEM) are isolated and enriched. Our manufacturingprocess limits ex vivo expansion, which is designed to reduce T cell exhaustion and maintain a T_CM or T_N/MEM phenotype.Based on experiments with CAR-Ts in mouse xenograft models of GBM, these CAR-modified T_CM and T_N/MEM cells havebeen shown to be more potent and persistent than earlier generations of CAR-T cells.

Our academic partners at COHhave recently completed the treatment phase of their Phase 1 study, which was designed to assess the feasibility and safety of using T_CMor T_N/MEM enriched IL13Rα2-specific CAR-engineered T cells for clinical study participants with IL13Rα2 recurrent/refractorymalignant glioma (ClinicalTrials.gov Identifier: NCT02208362). In this study, COH enrolled and treated 65 patients, with 58 patients receiving3 cycles of CAR T cells per the study protocol. Preliminary data indicated that the CAR-T cells were well tolerated, and no dose-limitingtoxicities were observed in any of the study arms, nor were there any occurrences of CRS or treatment-related deaths. Of the 58 patientsevaluable for disease response, 50% achieved stable disease (SD) or better; 22%, including 8 patients with grade 4 gliomas, achieved SDor better for at least 90 days. Two patients achieved partial response, and one patient achieved complete response on the study. In 2016COH reported that a patient had achieved a complete response to treatment based on the imaging and clinical features set forth by theResponse Assessment in Neuro-Oncology Criteria (“RANO”). This result was published as a case report in the New EnglandJournal of Medicine (Brown CE et al. NEJM. 2016;375:2561-9). As described in the paper, this patient diagnosed with recurrentmultifocal glioblastoma received multiple infusions of IL13Rα2-specific CAR-T cells over 220 days through two intracranial deliveryroutes – infusions into the resected tumor cavity followed by infusions into the ventricular system. Intracranial infusions of IL13Rα2-targetedCAR-T cells were not associated with any toxic effects of grade 3 or higher. After CAR-T cell treatment, regression of all intracranialand spinal tumors was observed, along with corresponding increases in levels of cytokines and immune cells in the cerebrospinal fluid.This clinical response was sustained for 7.5 months after the initiation of CAR T-cell therapy; however, the patient’s disease eventuallyrecurred at four new locations that were distinct and non-adjacent to the original tumors, and biopsy of one of these lesions showed decreasedexpression of IL13Rα2.

Results from this COH study have laid the foundationfor potentially three new MB-101 studies listed below. Due to limited resources, we do not expect to initiate study #3 below until suchtime, if any, that additional resources become available to us.

MB- 108 (HSV 1 oncolytic virus C134) 

MB-108 is a next-generationoncolytic herpes simplex virus (“oHSV”) that is conditionally replication competent; that is, it can replicate in tumor cells,but not in normal cells, thus killing the tumor cells directly through this process. Replication of C134 in the tumor itself not onlykills the infected tumor cells but causes the tumor cell to act as a factory to produce new virus. These virus particles are releasedas the tumor cell dies and can then proceed to infect other tumor cells in the vicinity and continue the process of tumor kill. In additionto this direct oncolytic activity, the virus promotes an immune response against surviving tumor cells, which increases the antitumoreffect of the therapy. The virus expresses a gene from another virus from the same overall virus family, human cytomegalovirus, whichallows it to replicate better in the tumor cells than its first-generation predecessors. However, the virus has also been geneticallyengineered to minimize the production of any toxic effects for the patient receiving the therapy.

To improve this virus overits first-generation predecessors, modifications have focused on improving viral replication and spread within the tumor bed and on enhancingbystander damage to uninfected tumor cells. These effects cumulatively should result in converting an immunologically cold tumor to animmunologically hot tumor, which we anticipate will increase the efficacy of our IL13Rα2 directed CAR T for the treatment of GBMand high-grade astrocytoma.

The O’Neal ComprehensiveCancer Center at the UAB is the single clinical trial site for the Phase 1 trial of MB-108, and this site has initiated a Phase 1 trialthat began enrolling patients in 2019 (ClinicalTrials.gov Identifier: NCT03657576). The primary objective of this study is to determinethe safety and tolerability of a single dose of MB-108 administered via a stereotactic intracerebral injection and to determine the maximallytolerated dose (“MTD”) of the oncolytic virus. Secondary objectives are to obtain preliminary information about the potentialbenefit of MB-108 in the treatment of patients with recurrent malignant gliomas, including relevant data on markers of efficacy, timeto tumor progression and patient survival. As of April 2023, 9 patients had been enrolled in this study.

RecentDevelopments 

Saleof Manufacturing Facility – Overview of Transaction 

On May 18, 2023, we enteredinto an Asset Purchase Agreement (the “Original Asset Purchase Agreement”) with uBriGene (Boston) Biosciences, Inc., a Delawarecorporation (“uBriGene”), pursuant to which we agreed to sell our leasehold interest in our cell processing facility locatedin Worcester, Massachusetts (the “Facility”), and associated assets relating to the manufacturing and production of cell andgene therapies at the Facility to uBriGene (the “Transaction”). We and uBriGene subsequently entered into Amendment No. 1,dated as of June 29, 2023, and Amendment No. 2, dated as of July 28, 2023, to the Original Asset Purchase Agreement (the Original AssetPurchase Agreement, as so amended, the “Prior Asset Purchase Agreement”).

On July 28, 2023 (the “ClosingDate”), pursuant to the Prior Asset Purchase Agreement, we completed the sale of all of our assets that primarily relate to themanufacturing and production of cell and gene therapies at the Facility (such operations, the “Transferred Operations” andsuch assets, the “Transferred Assets”) to uBriGene for upfront consideration of $6 million cash (the “Base Amount”).The Transferred Assets that were transferred to uBriGene on the Closing Date include, but are not limited to: (i) our leases of equipmentand other personal property and all other property, equipment, machinery, tools, supplies, inventory, fixtures and all other personalproperty primarily related to the Transferred Operations, (ii) the data, information, methods, quality management systems, and intellectualproperty primarily used for the purposes of the Transferred Operations, (iii) the records and filings, including customer and vendor lists,production data, standard operating procedures and business records relating to, used in or arising under the Transferred Operations and(iv) all transferrable business license, permits and approvals necessary to operate the Transferred Operations. Certain Transferred Assets,including our lease of the Facility and contracts that are primarily used in the Transferred Operations (the “Transferred Contracts”)did not transfer to uBriGene on the Closing Date.

VoluntaryNotice to U.S. Committee on Foreign Investment in the United States 

uBriGene is an indirect, whollyowned subsidiary of UBrigene (Jiangsu) Biosciences Co., Ltd., a Chinese contract development and manufacturing organization. Under thePrior Asset Purchase Agreement, we and uBriGene agreed to use our reasonable best efforts to obtain clearance for the Transaction fromthe U.S. Committee on Foreign Investment in the United States (“CFIUS”), although obtaining such clearance was not a conditionto closing the Transaction. In accordance with the Prior Asset Purchase Agreement, we and uBriGene previously submitted a voluntary jointnotice to CFIUS on August 10, 2023.

Following an initial 45-dayreview period and subsequent 45-day investigation period, on November 13, 2023, CFIUS requested that we and uBriGene withdraw and re-fileour joint voluntary notice to allow more time for review and discussion regarding the nature and extent of national security risk posedby the Transaction. Upon CFIUS’s request, we and uBriGene submitted a request to withdraw and re-file our joint voluntary noticeto CFIUS, and on November 13, 2023, CFIUS granted this request, accepted the joint voluntary notice and commenced a new 45-day reviewperiod on November 14, 2023. CFIUS’s 45-day review ended on December 28, 2023. Since CFIUS had not concluded its review by December28, 2023, the proceeding transitioned to a subsequent 45-day investigation period, which ended on February 12, 2024.

Following the 45-day reviewperiod and subsequent 45-day investigation period described above, on February 12, 2024, we and uBriGene requested permission to withdrawand re-file our joint voluntary notice to allow more time for review and discussion regarding the nature and extent of national securityrisk posed by the Transaction. Upon our joint request to withdraw and re-file their joint voluntary notice to CFIUS, on February 12, 2024,CFIUS granted this request, accepted the joint voluntary notice and commenced a new 45-day review period on February 13, 2024. CFIUS’snew 45-day review ended on March 28, 2024. Because CFIUS had not yet concluded its action, the proceeding transitioned to a second 45-dayphase as CFIUS further investigated the Transaction. On March 28, 2024, CFIUS advised us that its investigation would be completed nolater than May 13, 2024.

OnMay 13, 2024, together with uBriGene and CFIUS, we executed a National Security Agreement (the “NSA”), pursuant to which weand uBriGene agreed to abandon the Transaction and all other transactions contemplated by the Asset Purchase Agreement and the agreementsentered into in connection therewith. The execution of the NSA was the result of CFIUS’ determination that such transactions poseda risk to the national security of the United States. We disagree with this position but did not feel a meaningful likelihood existedthat the Transaction would be consummated in light of CFIUS’ objections. The NSA imposes certain conditions on us and uBriGene andits affiliates. Most significantly, we agreed (i) not to effect the Transaction with uBriGene or any of its affiliates; and (ii) to appointa point of contact representative with whom CFIUS and uBriGene’s designated contact person may interact as needed. The NSA alsoobligates uBriGene to sell, or otherwise dispose of, the equipment assets purchased within 180 days after the execution of the NSA, withuBriGene able to eliminate some of its obligations under the NSA if it is able to sell the equipment assets purchased back to us within45 days after the execution of the NSA (an “Expedited Divestment”).

June 2024 Repurchase of Assets

On June 27, 2024 (the “EffectiveDate”), we entered into an Asset Purchase Agreement (the “Asset Purchase Agreement”) with uBriGene, pursuant to whichwe agreed, subject to the terms and conditions set forth therein, to repurchase (the “Repurchase Transaction”) the assets,properties and rights previously transferred by the Company to uBriGene under the Asset Purchase Agreement, excluding any inventory transferredunder the Purchase Agreement that has been consumed or transferred to a third party by uBriGene since the closing of the Asset PurchaseAgreement (collectively, the “Repurchased Assets”). For the avoidance of doubt, “Repurchased Assets” also includesall MBio Assets (as such term is defined in the NSA) that were previously sold, transferred, conveyed, assigned, delivered, or contributedby us or our affiliates to uBriGene or its affiliates, to the extent such MBio Assets have not been consumed or transferred to a thirdparty by uBriGene since the closing of the Asset Purchase Agreement. The Repurchased Assets do not include inventory acquired by uBriGeneafter the closing of the Asset Purchase Agreement. We further agreed to assume all obligations, liabilities and commitments previouslytransferred by us to uBriGene under the Asset Purchase Agreement. The Repurchase Transaction was intended to constitute an Expedited Divestmentby uBriGene pursuant to the NSA with CFIUS.

As consideration for the RepurchaseTransaction, we agreed to pay to uBriGene a total purchase price (the “Purchase Price”) of $1,395,138, consisting of (i) anupfront payment of $100,000 due within five (5) business days of the Effective Date and a (ii) subsequent amount of $1,295,138 due onthe date that is twelve (12) months after the Closing (the “Deferred Amount”). In the event that as of the original (or anyextended) date on which the Deferred Amount is payable we have, as of the date of the public reporting of our then-most recent quarterlyaudited or unaudited financial statements, net assets below $20 million, then we may, upon written notice to uBriGene, elect to delayour payment obligation of the Deferred Amount by an additional six (6) months, with no limit on the number of such extensions availableto us. Notwithstanding the foregoing, if we have not paid the Deferred Amount in full as of the date that is 12 (twelve) months afterclosing of the Repurchase Transaction, any amounts that remain outstanding will accrue interest at a rate of 5% per annum beginning onthe date that is 12 (twelve) months after closing and until the Deferred Amount is paid in full.

The Asset Purchase Agreementcontains customary representations and warranties from both us and uBriGene with respect to each party. Additionally, we agreed to providea purchase price allocation schedule to uBriGene within sixty (60) days of the Effective Date.

Pursuant to the terms of theAsset Purchase Agreement, we and uBriGene terminated the following agreements between us that were entered into in connection with theAsset Purchase Agreement: (i) the Manufacturing Services Agreement, dated July 28, 2023, and work orders entered into under such agreement,(ii) the Quality Services Agreement, dated July 28, 2023, (iii) the Subcontracting CDMO Agreement, dated July 28, 2023, and work ordersentered into under such agreement, (iv) the Quality Services Agreement, dated July 28, 2023, and (v) the Transition Services Agreement.

Notificationof Non-Compliance with Nasdaq Continued Listing Requirements 

On March 13, 2024, we receiveda deficiency letter (the “Letter”) from the Listing Qualifications Department (the “Staff”) of The Nasdaq StockMarket LLC (“Nasdaq”) notifying us that we were not in compliance with the minimum stockholders’ equity requirementfor continued listing on the Nasdaq Capital Market under Nasdaq Listing Rule 5550(b)(1). Nasdaq Listing Rule 5550(b)(1) requires companieslisted on the Nasdaq Capital Market to maintain stockholders’ equity of at least $2,500,000 (the “Stockholders’ EquityRequirement”). As of December 31, 2023, we reported stockholders’ equity of $123,000. The Letter further noted that as ofits date, we did not have a market value of listed securities of $35 million, or net income from continued operations of $500,000 in themost recently completed fiscal year or in two of the last three most recently completed fiscal years, the alternative quantitative standardsfor continued listing on the Nasdaq Capital Market.

The Letter had no immediateeffect on our continued listing on the Nasdaq Capital Market, subject to our compliance with the other continued listing requirements.In accordance with Nasdaq rules, we were provided 45 calendar days, or until April 29, 2024, to submit a plan to regain compliance (the “Compliance Plan”). We submitted our Compliance Plan on April 29, 2024, and the Staff granted our request for an extensionof 180 calendar days through September 9, 2024, to regain compliance with the Stockholders’ Equity Requirement.

OnMay 16, 2024, we received a notice (the “Second Letter”) from the Staff of Nasdaq indicating that the bid price of our commonstock had closed below $1.00 per share for 31 consecutive business days and, as a result, we were not in compliance with Nasdaq ListingRule 5550(a)(2), which sets forth the minimum bid price requirement for continued listing on the Nasdaq Capital Market. The Second Letterfrom Nasdaq had no immediate effect on the listing of our common stock on Nasdaq. Pursuant to Nasdaq Listing Rule 5810(c)(3)(A), we wereafforded a 180-calendar day grace period, or until November 12, 2024, to regain compliance with the bid price requirement. Compliancecan be achieved by evidencing a closing bid price of at least $1.00 per share for a minimum of ten consecutive business days (but generallynot more than 20 consecutive business days) during the 180-calendar day grace period.

Ifwe do not regain compliance with the bid price requirement by November 12, 2024, we may be eligible for an additional 180-calendar daycompliance period so long as we satisfy the criteria for initial listing on Nasdaq and the continued listing requirement for market valueof publicly held shares and we provide written notice to Nasdaq of our intention to cure the deficiency during the second compliance periodby effecting a reverse stock split, if necessary. In the event we are not eligible for the second grace period, Nasdaq staff will providewritten notice that our common stock is subject to delisting; however, we may request a hearing before the Nasdaq Hearings Panel (the “Panel”), which request, if timely made, would stay any further suspension or delisting action by the Staff pending the conclusionof the hearing process and expiration of any extension that may be granted by the Panel. There can be no assurance that we would be successfulin our efforts to maintain the listing of our common stock on the Nasdaq Capital Market.

April2024 Reduction in Work Force 

OnApril 10, 2024, our board of directors approved a reduction of our workforce by approximately 81% of our employee base in order to reducecosts and preserve capital due to the fundraising environment and continued uncertainty regarding the CFIUS review of the sale of theFacility and the Transaction with uBriGene. The workforce reduction took place primarily in April 2024 and was completed in the secondquarter of 2024. As a result of these actions, we incurred personnel-related restructuring charges of approximately $0.2 million in connectionwith one-time employee termination cash expenditures, which were incurred in the second quarter of 2024. We and our board of directorscontinue to evaluate all strategic and other alternatives related to the business.

Due to limited resources,and as a result of the reduction in work force described above, we do not expect to initiate our pivotal Phase 2 single-arm clinical trialof MB-106 for the treatment of WM trial in 2024. Subject to available funds, we intend rely on third party service providers to conductstudy and manufacturing services to advance our priority potential product candidates.

May 2024 Public Offering

OnApril 29, 2024, we commenced a best efforts public offering with an institutional investor (the “Investor”) (the “May2024 Offering”) of an aggregate of (i) 1,160,000 shares of common stock, (ii) pre-funded warrants (the “May 2024 Pre-FundedWarrants”) to purchase up to an aggregate of 15,717,638 shares of common stock (the “May 2024 Pre-Funded Warrant Shares”),(iii) Series A-1 warrants (the “Series A-1 Warrants”) to purchase up to an aggregate of 16,877,638 shares of common stock(the “Series A-1 Warrant Shares”), (iv) Series A-2 warrants (the “Series A-2 Warrants”) to purchase up to an aggregateof 16,877,638 shares of common stock (the “Series A-2 Warrant Shares”), and (v) Series A-3 warrants (the “Series A-3Warrants,” and together with the Series A-1 Warrants and Series A-2 Warrants, the “Warrants”) to purchase up to an aggregateof 16,877,638 shares of common stock (the “Series A-3 Warrant Shares”). Each share of common stock or May 2024 Pre-FundedWarrant was sold together with one Series A-1 Warrant to purchase one share of common stock, one Series A-2 Warrant to purchase one shareof common stock, and one Series A-3 Warrant to purchase one share of common stock. The public offering price for each share of commonstock and accompanying Warrants was $0.237, and the public offering price for each May 2024 Pre-Funded Warrant and accompanying Warrantswas $0.2369. The May 2024 Pre-Funded Warrants have an exercise price of $0.0001 per share, were exercisable immediately and will expirewhen exercised in full. Each Warrant has an exercise price of $0.237 per share, will be exercisable beginning on the effective date ofstockholder approval of the issuance of the shares upon exercise of the Warrants (the “Warrant Stockholder Approval”). TheSeries A-1 Warrant will expire on the five-year anniversary of the Warrant Stockholder Approval. The Series A-2 Warrant will expire onthe twenty-four-month anniversary of the Warrant Stockholder Approval. The Series A-3 Warrant will expire on the nine-month anniversaryof the Warrant Stockholder Approval.

Thenet proceeds of the May 2024 Offering, after deducting the fees and expenses of the Placement Agent (as defined below), described in moredetail below, and other offering expenses payable by us, but excluding the net proceeds, if any, from the exercise of the Warrants, wasapproximately $3.3 million. The May 2024 Offering closed on May 2, 2024.

Inconnection with the May 2024 Offering, we also entered into a warrant amendment agreement (the “Warrant Amendment Agreement”)with the Investor. Under the Warrant Amendment Agreement, we agreed to amend certain existing warrants to purchase up to 2,588,236 sharesof common stock that were previously issued in October 2023 to the Investor, with an exercise price of $1.58 per share (the “ExistingWarrants”), in consideration for their purchase of the securities in the May 2024 Offering, as follows: (i) lower the exercise priceof the Existing Warrants to $0.237 per share, (ii) provide that the Existing Warrants, as amended, will not be exercisable until the receiptof Warrant Stockholder Approval for the exercisability of the Warrants in the May 2024 Offering, and (iii) extend the original expirationdate of the Existing Warrants by five years following the receipt of such Warrant Stockholder Approval. The Warrant Amendment Agreementbecame effective on May 2, 2024.

May 2024 At the MarketOffering Agreement

OnMay 31, 2024, we entered into an At the Market Offering Agreement (the “ATM Agreement”) with H.C. Wainwright & Co. LLC(the “Manager”) under which we may offer and sell, from time to time at our sole discretion, shares of our common stock (the “ATM Shares”), through or to the Manager. The offer and sale, if any, of ATM Shares by us under the Offering Agreement willbe made pursuant to our registration statement on Form S-3 (File No. 333-279891) (the “Registration Statement”) under theSecurities Act, and the related prospectus included therein, filed with the SEC on May 31, 2024, and declared effective on June 12, 2024.

Underthe ATM Agreement, the Manager may sell ATM Shares by any method permitted by law deemed to be an “at the market offering”as defined in Rule 415(a)(4) under the Securities Act. The Manager will use commercially reasonable efforts to sell the ATMShares from time to time, based upon instructions from us (including any price, time or size limits or other customary parameters or conditionswe may impose). We will pay the Manager a commission of 3.0% of the gross proceeds from the sales of ATM Shares sold through the Managerunder the ATM Agreement and have provided the Manager with customary indemnification and contribution rights. We will also reimburse theManager for certain expenses incurred in connection with the ATM Agreement. The Company and the Manager may each terminate the ATM Agreementat any time upon specified prior written notice.

Theoffering of ATM Shares pursuant to the ATM Agreement will terminate upon the earlier of (i) the sale of all ATM Shares subject to theATM Agreement or (ii) the termination of the ATM Agreement in accordance with its terms.

Termination of 2018At Market Issuance Sales Agreement

OnMay 31, 2024, we delivered notice to B. Riley Securities, Inc. (formerly B. Riley FBR, Inc.), Cantor Fitzgerald & Co., and the Manager(collectively, the “Agents”) to terminate our At Market Issuance Sales Agreement, dated July 27, 2018, as amended on July20, 2020, December 31, 2020, and April 14, 2023 (collectively, the “2018 Sales Agreement”), with the Agents. Termination ofthe 2018 Sales Agreement was effective June 5, 2024, pursuant to Section 13(b) of the 2018 Sales Agreement.

Pursuantto the terms of the 2018 Sales Agreement, we were previously able to issue and sell, from time to time through or to the Agents, sharesof our common stock, having an aggregate offering price of up to $100,000,000, subject to the limitations of Instruction I.B.6 of FormS-3. As a result of the termination of the 2018 Sales Agreement, we will not issue or sell any additional shares of our common stock underthe 2018 Sales Agreement. 

June 2024 Registered Direct Offering and ConcurrentPrivate Placement of Warrants

On June 19, 2024, we enteredinto a Securities Purchase Agreement (the “Purchase Agreement”) with Armistice Capital Master Fund Ltd. (“Armistice”),an institutional accredited investor, pursuant to which we agreed to issue and sell, in a registered direct offering priced at-the-marketunder the rules of Nasdaq (the “Registered Direct Offering”), (i) 3,025,000 shares of common stock, at a price per Share of$0.41 and (ii) pre-funded warrants (the “Pre-Funded Warrants”) to purchase up to 3,105,000 shares of our common stock, ata price per Pre-Funded Warrant equal to $0.4099, the price per share of common stock, less $0.001.

The Pre-Funded Warrants weresold, in lieu of shares of common stock, to Armistice, whose purchase of shares of common stockin the Registered Direct Offering would otherwise result in Armistice, together with its affiliates and certain related parties, beneficiallyowning more than 4.99% (or, at Armistice’s option upon issuance, 9.99%) of our outstanding common stock immediately following theconsumption of the Registered Direct Offering. The Pre-Funded Warrants have an exercise price of $0.0001 per share, became exercisableupon issuance and remain exercisable until exercised in full.

TheRegistered Direct Offering closed on June 21, 2024. We intend to use the net proceeds from the Registered Direct Offering for generalcorporate purposes and working capital requirements.

Ina concurrent private placement, pursuant to the terms of the Purchase Agreement, we also agreed to issue and sell to Armistice unregisteredwarrants (the “Private Placement Warrants”) to purchase up to 6,130,000 shares of common stock, at an offering price of $0.41per Private Placement Warrant to purchase one share of common stock (the “Private Placement” and, together with the RegisteredDirect Offering, the “Offerings”) (which offering price was included in the purchase price per share of common stock or Pre-FundedWarrant). The Private Placement Warrants have an exercise price of $0.41 per share (subject to customary adjustments as set forth in thePrivate Placement Warrants), were exercisable upon issuance and will expire five and one-half years from the date of issuance. The PrivatePlacement Warrants contain customary anti-dilution adjustments to the exercise price, including for share splits, share dividends, rightsoffering and pro rata distributions.

H.C.Wainwright & Co., LLC (“Wainwright” and together with Armistice, the “Selling Stockholders”) acted as theexclusive placement agent in connection with the Offerings under an Engagement Letter, dated as of June 18, 2024, between us and Wainwright(the “Engagement Letter”). Pursuant to the Engagement Letter, we issued to Wainwright (or its designees) warrants to purchaseup to 367,800 shares of common stock (the “Wainwright Warrants” and, together with the Private Placement Warrants, the “2024Warrants”). The Wainwright Warrants have substantially the same terms as the Private Placement Warrants, except that the WainwrightWarrants will expire five years from the commencement of the sales of the Offerings and have an exercise price of $0.5125 per share (subjectto customary adjustment as set forth in the Wainwright Warrants), representing 125% of the purchase price per share of common stock inthe Registered Direct Offering.

Summary Risk Factors

Our business is subject torisks of which you should be aware before making an investment decision. You should carefully consider the risk factors described underthe heading “Risk Factors,” and in the other reports and documents that we have filed with the SEC.

Corporate Information

We are a majority-controlledsubsidiary of Fortress Biotech, Inc. We were incorporated under the laws of the State of Delaware on March 13, 2015. Our principal executiveoffices are located at 377 Plantation Street, Worcester, Massachusetts 01605, and our telephone number is 781-652-4500. We maintain awebsite on the Internet at www.mustangbio.com and our e-mail address is info@mustangbio.com. Information on our website, or any otherwebsite, is not incorporated by reference in this prospectus. We have included our website address in this prospectus solely as an inactivetextual reference.

Implicationsof Being a Smaller Reporting Company 

We are a smaller reportingcompany as defined in the Securities Exchange Act of 1934, as amended (the “Exchange Act”). We may take advantage of certainof the scaled disclosures available to smaller reporting companies and will be able to take advantage of these scaled disclosures forso long as (i) the market value of our voting and non-voting common stock held by non-affiliates is less than $250 million measured onthe last business day of our second fiscal quarter or (ii) our annual revenue is less than $100 million during the most recently completedfiscal year and the market value of our voting and non-voting common stock held by non-affiliates is less than $700 million measured onthe last business day of our second fiscal quarter. Specifically, as a smaller reporting company, we may choose to present only the twomost recent fiscal years of audited financial statements in our Annual Reports on Form 10-K and have reduced disclosure obligations regardingexecutive compensation, and if we are a smaller reporting company with less than $100 million in annual revenue, we would not be requiredto obtain an attestation report on internal control over financial reporting issued by our independent registered public accounting firm.

THE OFFERING

The Selling Stockholders identifiedin this prospectus are offering on a resale basis a total of 6,497,800 shares of common stockunderlying the 2024 Warrants, as more fully described below.

(1)           Thenumber of shares of common stock to be outstanding after this offering is based on 34,432,138 shares of our common stock outstanding asof July 16, 2024, and excludes:

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documentsincorporated herein by reference contain predictive or “forward-looking statements” within the meaning of the Securities Actand the Exchange Act and involve known and unknown risks, uncertainties and other factors that may cause our actual results, performanceor achievements to be materially different from the future results, performance or achievements expressed or implied by such forward-lookingstatements. The words “anticipate,” “believe,” “estimate,” “may,” “expect”and similar expressions are generally intended to identify forward-looking statements. Such forward-looking statements include, but arenot limited to, statements about our:

We have based these forward-lookingstatements largely on our current expectations, estimates, forecasts, and projections about future events and financial trends that webelieve may affect our financial condition, results of operations, business strategy, and financial needs. In light of the significantuncertainties in these forward-looking statements, you should not rely upon forward-looking statements as predictions of future events.Although we believe that we have a reasonable basis for each forward-looking statement contained in this prospectus, we cannot guaranteethat the future results, levels of activity, performance, or events and circumstances reflected in the forward-looking statements willbe achieved or occur at all. You should refer to the section entitled “Risk Factors” in this prospectus and the riskfactors set forth in the documents incorporated by reference in this prospectus for a discussion of important factors that may cause ouractual results to differ materially from those expressed or implied by our forward-looking statements. Furthermore, if our forward-lookingstatements prove to be inaccurate, the inaccuracy may be material. Except as required by law, we undertake no obligation to publicly updateany forward-looking statements, whether as a result of new information, future events or otherwise.

You should read this prospectusand the documents incorporated by reference in this prospectus completely and with the understanding that our actual future results maybe materially different from what we expect. We qualify all of the forward-looking statements in this prospectus by these cautionary statements.

RISK FACTORS

Investingin our common stock involves a high degree of risk. Our business is influenced by many factors thatare difficult to predict, involve uncertainties that may materially affect actual results and are often beyond our control. We have identifiedsome of these factors below and under the heading “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2023, as supplemented by our Quarterly Report on Form 10-Q for the quarter ended March 31, 2024, which is incorporated by referencein this prospectus, as well as in other information included or incorporated by reference in this prospectus and any prospectus supplement.You should consider carefully these risks and uncertainties before deciding to invest in our common stock. If any of the risksidentified herein or the risks identified as risk factors in the incorporated documents were to materialize, our business, financial condition,results of operations, and future growth prospects could be materially and adversely affected. In that event, the market price of ourcommon stock could decline, and you could lose part of or all of your investment in our common stock. Seethe section of this prospectus titled “Where You Can Find More Information.” 

RisksRelated to the Company and this Offering 

There is substantial doubt about our abilityto continue as a going concern, which may hinder our ability to obtain future financing.

We are not yet generatingrevenue, have incurred substantial operating losses since our inception and expect to continue to incur significant operating losses forthe foreseeable future as we execute on our product development plan and may never become profitable. As of March 31, 2024, we hadcash and cash equivalents of $1.3 million and an accumulated deficit of $386.2 million, and, as of December 31, 2023, we had cashand cash equivalents of $6.2 million and an accumulated deficit of $381.0 million. We do not believe that our cash is sufficient for thenext twelve months. As a result, there is substantial doubt about our ability to continue as a going concern. Our ability to continueas a going concern will depend on our ability to obtain additional funding, as to which no assurances can be given. If we are unable toobtain funds when needed or on acceptable terms, we may be required to curtail our current development programs, cut operating costs,forgo future development and other opportunities or even terminate our operations.

Wecontract with third parties for the manufacture of our product candidates for preclinical and clinical testing and may also do so forcommercialization, if and when our product candidates are approved. This reliance on third parties increases the risk that we will nothave sufficient quantities of our product candidates or any future product candidate or such quantities at an acceptable cost, which coulddelay, prevent or impair our development or commercialization efforts. 

Dueto limited resources, and in light of our reduction in work force in April 2024, we may increase our reliance on third-party manufacturersor third-party collaborators for the manufacture of commercial supply of one or more product candidates for which our collaborators orwe obtain marketing approval. We may be unable to establish any agreements with third-party manufacturers or to do so on acceptable terms.Even if we are able to establish agreements with third-party manufacturers, reliance on third-party manufacturers entails additional risks,including, but not necessarily limited to:

Werely on our third-party manufacturers to produce or purchase from third-party suppliers the materials and equipment necessary to produceour product candidates for our preclinical and clinical trials. Forces beyond our control could disrupt the global supply chain and impactour or our third-party manufacturers’ ability to obtain raw materials or other products necessary to manufacture our product candidates.There are a limited number of suppliers for raw materials and equipment that we use (or that are used on our behalf) to manufacture ourproduct candidates, and there may be a need to assess alternate suppliers to prevent a possible disruption of the manufacture of the materialsand equipment necessary to produce our product candidates for our preclinical and clinical trials, and if approved, ultimately for commercialsale. We do not have any control over the process or timing of the acquisition of these raw materials or equipment by our third-partymanufacturers. Any significant delay in the supply of a product candidate, or the raw material components thereof, for an ongoing preclinicalor clinical trial due to the need to replace a third-party manufacturer could considerably delay completion of our preclinical or clinicaltrials, product testing and potential regulatory approval of our product candidates. If our manufacturers or we are unable to purchasethese raw materials or equipment after regulatory approval has been obtained for our product candidates, the commercial launch of ourproduct candidates would be delayed or there would be a shortage in supply, which would impair our ability to generate revenues from thesale of our product candidates.

Thefacilities used by contract manufacturers to potentially manufacture our product candidates must be approved by the FDA pursuant to inspectionsthat will be conducted after we submit a New Drug Application (NDA) or BLA to the FDA. We are required by law to establish adequate oversightand control over raw materials, components and finished products furnished by our contract manufacturers, but we do not control the day-to-daymanufacturing operations of, and are dependent on, the contract manufacturers for compliance with current Good Manufacturing Practices(“cGMP”) regulations for manufacture of our product candidates. Third-party manufacturers may not be able to comply with thecGMP regulations or similar regulatory requirements outside the United States. Our failure, or the failure of our third-party manufacturers,to comply with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, restrictionson imports and exports, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of productcandidates or products, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect suppliesof our products.

Oneor more of the product candidates that we may develop may compete with other product candidates and products for access to manufacturingfacilities. There are a limited number of manufacturers that operate under cGMP regulations and that might be capable of manufacturingfor us. Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval.We do not currently have arrangements in place for redundant supply. If our current contract manufacturers cannot perform as agreed, wemay be required to replace such manufacturers. We may incur added costs and delays in identifying and qualifying any replacement manufacturers.

Futuredependence upon others for the manufacture of our product candidates or products may adversely affect our future profit margins and ourability to commercialize any products that may receive marketing approval on a timely and competitive basis. We also expect to rely onthird parties to distribute drug supplies for our clinical trials. Any performance failure on the part of our distributors could delayclinical development or marketing approval of our product candidates or commercialization of our products, if approved, producing additionallosses and depriving us of potential product revenue.

The trading price of the shares of our commonstock has been and is likely to continue to be highly volatile, and purchasers of our common stock could incur substantial losses.

Our stock price has been andwill likely continue to be volatile for the foreseeable future. The stock market in general and the market for biotechnology companiesin particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies.As a result of this volatility, investors may not be able to sell their common stock at or above the price they paid.

In addition, in the past,stockholders have initiated class action lawsuits against biotechnology and pharmaceutical companies following periods of volatility inthe market prices of these companies’ securities. Such litigation and any litigation that may be instituted against us, our officersand/or our directors in the future, could cause us to incur substantial costs and divert management’s attention and resources, whichcould have a material adverse effect on our business, financial condition and results of operations.

A substantial number of shares of our commonstock could be sold into the public market in the near future, which could depress our stock price.

Sales of substantial amountsof common stock in the public market could reduce the prevailing market prices for our common stock. Substantially all of our outstandingcommon stock is eligible for sale as are shares of common stock issuable under vested and exercisable stock options. If our existing stockholderssell a large number of shares of our common stock, or the public market perceives that existing stockholders might sell shares of commonstock, the market price of our common stock could decline significantly. These sales might also make it more difficult for us to sellequity securities at a time and price that we deem appropriate.

We do not intend to pay dividends on ourcommon stock, so any returns will be limited to increases, if any, in our common stock’s value. Your ability to achieve a returnon your investment will depend on appreciation, if any, in the price of our common stock.

We currently anticipate thatwe will retain future earnings for the development, operation and expansion of our business and do not anticipate declaring or payingany cash dividends for the foreseeable future. Any future determination to declare dividends will be made at the discretion of our boardof directors and will depend on, among other factors, our financial condition, operating results, capital requirements, general businessconditions and other factors that our board of directors may deem relevant. Any return to stockholders will therefore be limited to theappreciation in the value of their stock, if any.

If we are unable to maintain compliancewith all applicable continued listing requirements and standards of Nasdaq, our common stock may be delisted from Nasdaq.

On March 13, 2024, we receiveda Letter from the Staff of Nasdaq notifying us that we were not in compliance with the minimum stockholders’ equity requirementfor continued listing on the Nasdaq Capital Market under Nasdaq Listing Rule 5550(b)(1). Nasdaq Listing Rule 5550(b)(1) requires companieslisted on the Nasdaq Capital Market to maintain the Stockholders’ Equity Requirement. As of December 31, 2023, we reported stockholders’equity of $123,000. The Letter further noted that as of its date, we did not have a market value of listed securities of $35 million,or net income from continued operations of $500,000 in the most recently completed fiscal year or in two of the last three most recentlycompleted fiscal years, the alternative quantitative standards for continued listing on the Nasdaq Capital Market.

The Letter has no immediateeffect on our continued listing on the Nasdaq Capital Market, subject to our compliance with the other continued listing requirements.In accordance with Nasdaq rules, we were provided 45 calendar days, or until April 29, 2024, to submit a plan to regain compliance (the “Compliance Plan”). We submitted our Compliance Plan on April 29, 2024 and the Staff granted our request for an extensionof 180 calendar days through September 9, 2024 to regain compliance with the Stockholders’ Equity Requirement.

On May 16, 2024, we receiveda notice (the “Second Letter”) from the Staff of Nasdaq indicating that the bid price of our common stock had closed below$1.00 per share for 31 consecutive business days and, as a result, we were not in compliance with Nasdaq Listing Rule 5550(a)(2), whichsets forth the minimum bid price requirement for continued listing on the Nasdaq Capital Market. The Second Letter from Nasdaq had noimmediate effect on the listing of our common stock on Nasdaq. Pursuant to Nasdaq Listing Rule 5810(c)(3)(A), we were afforded a 180-calendarday grace period, or until November 12, 2024, to regain compliance with the bid price requirement. Compliance can be achieved by evidencinga closing bid price of at least $1.00 per share for a minimum of ten consecutive business days (but generally not more than 20 consecutivebusiness days) during the 180-calendar day grace period.

If we do not regain compliancewith the bid price requirement by November 12, 2024, we may be eligible for an additional 180-calendar day compliance period so long aswe satisfy the criteria for initial listing on Nasdaq and the continued listing requirement for market value of publicly held shares andwe provide written notice to Nasdaq of its intention to cure the deficiency during the second compliance period by effecting a reversestock split, if necessary. In the event we are not eligible for the second grace period, Nasdaq staff will provide written notice thatour common stock is subject to delisting; however, we may request a hearing before the Nasdaq Hearings Panel (the “Panel”),which request, if timely made, would stay any further suspension or delisting action by the Staff pending the conclusion of the hearingprocess and expiration of any extension that may be granted by the Panel. Although we intend to take all reasonable measures availableto regain compliance under the Nasdaq Listing Rules and remain listed on the Nasdaq Capital Market, there can be no assurance that wewould be successful in its efforts to maintain listing on the Nasdaq Capital Market.

If we are delisted from Nasdaq,there can be no assurance that our common stock will be eligible for trading on another stock exchange or quotation on an over-the-countermarket. If we are not able to obtain a listing on another stock exchange or quotation service for our common stock, it may be extremelydifficult or impossible for stockholders to sell their shares. Additionally, if we are delisted from Nasdaq, but obtain a substitute listingor quotation service for our common stock, it will likely be on a market with less liquidity and our common stock may therefore experiencepotentially more price volatility than it has historically experienced on Nasdaq. Stockholders may not be able to sell their shares ofcommon stock on any such substitute market in the quantities, at the times, or at the prices that could potentially be available on amore liquid trading market. As a result of these factors, if our common stock is delisted from Nasdaq, the value and liquidity of ourcommon stock would likely be adversely affected. A delisting of our common stock from Nasdaq could also adversely affect our ability toobtain financing for our operations and/or result in a loss of confidence by investors, employees and/or business partners.

DIVIDEND POLICY

We have never declared orpaid any cash dividends on our common stock and do not anticipate paying any cash dividends in the foreseeable future. Any future determinationto pay dividends will be at the discretion of our board of directors and will depend on our financial condition, results of operations,capital requirements and other factors our board of directors deems relevant.

USE OF PROCEEDS

We will not receive any proceedsfrom the sale of the common stock covered by this prospectus and any accompanying prospectus supplement. All proceeds from the sale ofthe common stock will be for the respective accounts of the Selling Stockholders named herein.

We will bear all other costs,fees and expenses incurred in effecting the registration of the offering and sale of the common stock covered by this prospectus and anyaccompanying prospectus supplement, including, without limitation, all registration and filing fees, Nasdaq listing fees and fees andexpenses of our counsel and our accountants, in accordance with the terms of the Purchase Agreement. The Selling Stockholders will payany discounts, commissions, and fees of underwriters, selling brokers, dealer managers or similar securities industry professionals incurredby the Selling Stockholders in disposing of the common stock covered by this prospectus.

DETERMINATION OF OFFERING PRICE

The prices at which the sharesof common stock covered by this prospectus may actually be sold will be determined by the prevailing public market price for shares ofour common stock or be negotiations between the Selling Stockholders and buyers of our common stock in private transactions or as otherwisedescribed in “Plan of Distribution.”

THE SELLING STOCKHOLDERS

The shares of common stockbeing offered by the Selling Stockholders are those issuable to the Selling Stockholders upon exercise of the 2024 Warrants. For additionalinformation regarding the issuances of shares of common stock and 2024 Warrants, see “Prospectus Summary – June 2024 RegisteredDirect Offering and Concurrent Private Placement of Warrants” above. We are registering the resale of the shares of common stockissuable upon exercise of the 2024 Warrants in order to permit the Selling Stockholders to offer the shares for resale from time to time.H.C. Wainwright & Co. LLC has served as a financial advisor, sales agent, and placement agent for us in connection with several equityfinancings during the past three years. Except as set forth above, and except for the ownership of the shares of common stock and the2024 Warrants as well as their purchase of other securities from us in the past, the Selling Stockholders have not had any material relationshipwith us within the past three years.

The table below lists theSelling Stockholders and other information regarding the beneficial ownership of the shares of common stock by the Selling Stockholders.The second column lists the number of shares of common stock beneficially owned by the Selling Stockholders, based on its ownership ofthe shares of common stock and 2024 Warrants, as well as any other securities of ours owned by the Selling Stockholders, as of July 16,2024, assuming exercise of the 2024 Warrants held by the Selling Stockholders on that date, without regard to any limitations on exercises.

The third column lists theshares of common stock being offered by this prospectus by the Selling Stockholders.

In accordance with the termsof the Purchase Agreement, this prospectus covers the resale of the maximum number of shares of common stock issuable upon exercise ofthe 2024 Warrants, determined as if the outstanding 2024 Warrants were exercised in full as of the trading day immediately preceding thedate this registration statement was initially filed with the SEC, each as of the trading day immediately preceding the applicable dateof determination and all subject to adjustment as provided in the Purchase Agreement, without regard to any limitations on the exerciseof the 2024 Warrants. The third and fourth column assumes the sale of all of the shares offered by the Selling Stockholders pursuant tothis prospectus.

We cannot advise you as towhether the Selling Stockholders will in fact sell any or all of such common stock. In addition, the Selling Stockholders may sell, transferor otherwise dispose of, at any time and from time to time, the common stock and 2024 Warrants in transactions exempt from the registrationrequirements of the Securities Act after the date of this prospectus. For purposes of this table, we have assumed that the Selling Stockholderswill have sold all of the securities covered by this prospectus upon the completion of the offering.

Under the terms of the 2024Warrants, a selling stockholder may not exercise the 2024 Warrants to the extent such exercise would cause such selling stockholder, togetherwith its affiliates and attribution parties, to beneficially own a number of shares of common stock which would exceed 4.99% or 9.99%,as applicable, of our then-outstanding common stock following such exercise, excluding for purposes of such determination shares of commonstock issuable upon exercise of the 2024 Warrants that have not been exercised. The number of shares in the second and fourth columnsdo not reflect this limitation. The Selling Stockholders may sell all, some or none of its shares in this offering. See “Planof Distribution.”

PLAN OF DISTRIBUTION

The Selling Stockholders andany of their pledgees, assignees and successors-in-interest may, from time to time, sell any or all of its securities covered hereby onthe principal trading market or any other stock exchange, market or trading facility on which the securities are traded or in privatetransactions. These sales may be at fixed or negotiated prices. The Selling Stockholders may use any one or more of the following methodswhen selling securities:

The Selling Stockholders mayalso sell securities under Rule 144 or any other exemption from registration under the Securities Act, if available, rather than underthis prospectus. Broker-dealers engaged by the Selling Stockholders may arrange for other brokers-dealers to participate in sales. Broker-dealersmay receive commissions or discounts from the Selling Stockholders (or, if any broker-dealer acts as agent for the purchaser of securities,from the purchaser) in amounts to be negotiated, but, except as set forth in a supplement to this prospectus, in the case of an agencytransaction not in excess of a customary brokerage commission in compliance with FINRA Rule 2121; and in the case of a principal transactiona markup or markdown in compliance with FINRA Rule 2121.

In connection with the saleof the securities or interests therein, the Selling Stockholders may enter into hedging transactions with broker-dealers or other financialinstitutions, which may in turn engage in short sales of the securities in the course of hedging the positions they assume. The SellingStockholders may also sell securities short and deliver these securities to close out their short positions, or loan or pledge the securitiesto broker-dealers that in turn may sell these securities. The Selling Stockholders may also enter into option or other transactions withbroker-dealers or other financial institutions or create one or more derivative securities which require the delivery to such broker-dealeror other financial institution of securities offered by this prospectus, which securities such broker-dealer or other financial institutionmay resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The Selling Stockholders andany broker-dealers or agents that are involved in selling the securities may be deemed to be “underwriters” within the meaningof the Securities Act in connection with such sales. In such event, any commissions received by such broker-dealers or agents and anyprofit on the resale of the securities purchased by them may be deemed to be underwriting commissions or discounts under the SecuritiesAct. Each of the Selling Stockholders have informed us that it does not have any written or oral agreement or understanding, directlyor indirectly, with any person to distribute the securities.

We are required to pay certainfees and expenses incurred by us incident to the registration of the securities. We have agreed to indemnify the Selling Stockholdersagainst certain losses, claims, damages and liabilities, including liabilities under the Securities Act.

We agreed to keep this prospectuseffective until the earlier of (i) the date on which the securities may be resold by the Selling Stockholders without registration andwithout regard to any volume or manner-of-sale limitations by reason of Rule 144, without the requirement for us to be in compliance withthe current public information under Rule 144 under the Securities Act or any other rule of similar effect or (ii) all of the securitieshave been sold pursuant to this prospectus or Rule 144 under the Securities Act or any other rule of similar effect. The resale securitieswill be sold only through registered or licensed brokers or dealers if required under applicable state securities laws. In addition, incertain states, the resale securities covered hereby may not be sold unless they have been registered or qualified for sale in the applicablestate or an exemption from the registration or qualification requirement is available and is complied with.

Underapplicable rules and regulations under the Exchange Act, any person engaged in the distribution of the resale securities may not simultaneouslyengage in market making activities with respect to the common stock for the applicable restricted period, as defined in Regulation M,prior to the commencement of the distribution. In addition, the Selling Stockholders will be subject to applicable provisions of the ExchangeAct and the rules and regulations thereunder, including Regulation M, which may limit the timing of purchases and sales of the commonstock by the Selling Stockholders or any other person. We will make copies of this prospectus available to the Selling Stockholders andhave informed them of the need to deliver a copy of this prospectus to each purchaser at or prior to the time of the sale (including bycompliance with Rule 172 under the Securities Act).

DESCRIPTION OF CAPITAL STOCK

When used herein, the terms “Company,” “we,” “our,” and “us” refer to Mustang Bio, Inc.

Capital Stock

We are authorized to issue200,000,000 shares of common stock, par value of $0.0001 per share, of which 1,000,000 shares are designated as Class A common stock,and 2,000,000 of preferred stock, $0.0001 par value per share, of which 250,000 are designated as Class A Preferred Stock.

CommonStock 

The holders of common stockare entitled to one vote per share held.

As of July 16, 2024, therewere 34,432,138 shares of our common stock outstanding held by 71 stockholders of record.

The undesignated preferredstock may be issued from time to time in one or more series. Our board of directors is authorized to determine or alter the dividend rights,dividend rate, conversion rights, voting rights, rights and terms of redemption (including sinking fund provisions, if any), the redemptionprice or prices, the liquidation preferences and other designations, powers, preferences and relative, participating, optional or otherspecial rights, if any, and the qualifications, limitations and restrictions granted to or imposed upon any wholly unissued series ofpreferred stock, and to fix the number of shares of any series of preferred stock (but not below the number of shares of any such seriesthen outstanding).

Class A Common Stock

The holders of Class A commonstock are entitled to the number of votes equal to the number of whole shares of common stock into which the shares of Class A CommonShares held by such holder are convertible. For a period of ten years from issuance, the holders of the Class A common stock have theright to appoint one member of the Board of Directors of Mustang. To date, the holders of Class A common stock have not yet appointedsuch director.

Class A Preferred Stock

The Class A Preferred Stockis identical to undesignated common stock other than as to voting rights, conversion rights, and the PIK dividend right.

The holders of the outstandingshares of Class A Preferred Stock receive on each January 1 (each a “PIK Dividend Payment Date”) after the original issuancedate of the Class A Preferred Stock until the date all outstanding Class A Preferred Stock is converted into common stock or redeemed(and the purchase price is paid in full), pro rata per share dividends paid in additional fully paid and non-assessable shares of commonstock such that the aggregate number of shares of common stock issued pursuant to such PIK dividend is equal to 2.5% of the Corporation’sfully-diluted outstanding capitalization on the date that is one business day prior to any PIK Dividend Payment Date (“PIK RecordDate”). In the event the Class A Preferred Stock converts into common stock, the holders shall receive all PIK dividends accruedthrough the date of such conversion. No dividend or other distribution shall be paid, or declared and set apart for payment (other thandividends payable solely in capital stock on the capital stock) on the shares of common stock until all PIK dividends on the Class A PreferredStock shall have been paid or declared and set apart for payment. All dividends are non-cumulative.

On any matter presented tothe stockholders for their action or consideration at any meeting of stockholders (or by written consent of stockholders in lieu of meeting),each holder of outstanding shares of Class A Preferred Stock shall be entitled to cast for each share of Class A Preferred Stock heldby such holder as of the record date for determining stockholders entitled to vote on such matter, the number of votes that is equal toone and one-tenth (1.1) times a fraction, the numerator of which is the sum of (A) the number of shares of outstanding common stock and(B) the whole shares of common stock in to which the shares of outstanding Class A common stock and the Class A Preferred Stock are convertible,and the denominator of which is number of shares of outstanding Class A Preferred Stock. Thus, the Class A Preferred Stock will at alltimes constitute a voting majority.

Each share of Class A PreferredStock is convertible, at the option of the holder, into one fully paid and nonassessable share of common stock, subject to certain adjustments.If the Company, at any time effects a subdivision or combination of the outstanding common stock (by any stock split, stock dividend,recapitalization, reverse stock split or otherwise), the applicable conversion ratio in effect immediately before that subdivision isproportionately decreased or increased, as applicable, so that the number of shares of common stock issuable on conversion of each shareof Class A Preferred Stock shall be increased or decreased, as applicable, in proportion to such increase or decrease in the aggregatenumber of shares of common stock outstanding. Additionally, if any reorganization, recapitalization, reclassification, consolidation ormerger involving the Company occurs in which the common stock (but not the Class A Preferred Stock) is converted into or exchanged forsecurities, cash or other property, then each share of Class A Preferred Stock becomes convertible into the kind and amount of securities,cash or other property which a holder of the number of shares of common stock of the Company issuable upon conversion of one share ofthe Class A Preferred Stock immediately prior to such reorganization, recapitalization, reclassification, consolidation or merger wouldhave been entitled to receive pursuant to such transaction.

Additional Features

Other features of our capital stock include:

LEGAL MATTERS

Troutman Pepper Hamilton SandersLLP, Charlotte, North Carolina, will pass upon the validity of the securities being offered by this prospectus. Additional legal mattersmay be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The financial statements ofMustang Bio, Inc. as of December 31, 2023 and 2022, and for each of the years in the two-year period ended December 31, 2023, have beenincorporated by reference herein in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporatedby reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the December31, 2023, financial statements contains an explanatory paragraph that states the Company’s expectation to generate operating lossesand negative operating cash flows in the future, and the need for additional funding to support its planned operations raise substantialdoubt about its ability to continue as a going concern. The financial statements do not include any adjustments that might result fromthe outcome of that uncertainty.

WHERE YOU CAN FIND MORE INFORMATION

We file reports and proxystatements with the SEC. These filings include our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form8-K and proxy statements on Schedule 14A, as well as any amendments to those reports and proxy statements, which are available free ofcharge through our website as soon as reasonably practicable after we file them with, or furnish them to, the SEC. Our Internet websiteaddress is www.mustangbio.com. Our website and the information contained on, or that can be accessed through, the website will not bedeemed to be incorporated by reference in, and are not considered part of, this prospectus. You should not rely on any such informationin making your decision whether to purchase our securities. The SEC also maintains a website at www.sec.gov that contains reports, proxyand information statements and other information regarding us and other issuers that file electronically with the SEC.

We have filed with the SECa registration statement on Form S-1 under the Securities Act relating to the securities being offered by this prospectus. This prospectus,which constitutes part of that registration statement, does not contain all of the information set forth in the registration statementor the exhibits and schedules which are part of the registration statement. For further information about us and the securities offered,see the registration statement and the exhibits and schedules thereto. Statements contained in this prospectus regarding the contentsof any contract or any other document to which reference is made are not necessarily complete, and, in each instance where a copy of acontract or other document has been filed as an exhibit to the registration statement, reference is made to the copy so filed, each ofthose statements being qualified in all respects by the reference.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporateby reference” information from other documents that we file with it, which means that we can disclose important information to youby referring you to those documents. The information incorporated by reference is considered to be part of this prospectus. Informationin this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus. Weincorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information or documentslisted below that we filed with the SEC (File No. 001-38191):

Notwithstanding the statements in the precedingparagraphs, no document, report or exhibit (or portion of any of the foregoing) or any other information that we have “furnished”to the SEC pursuant to the Exchange Act shall be incorporated by reference into this prospectus.

We also incorporate by referenceinto this prospectus all documents (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed onsuch form that are related to such items) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the ExchangeAct (i) after the date of the initial filing of the registration statement of which this prospectus forms a part and prior to effectivenessof the registration statement, or (ii) after the date of this prospectus but prior to the termination of the offering. These documentsinclude periodic reports, such as Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K, as wellas proxy statements on Schedule 14A.

We will provide to each person,including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all ofthe documents that are incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that arespecifically incorporated by reference into such documents. You should direct any requests for documents to Mustang Bio, Inc., 377 PlantationStreet, Worcester, Massachusetts 01605, Attn: General Counsel, or by calling (781) 652-4500.

You also may access thesefilings on our website at www.mustangbio.com. We do not incorporate the information on our website into this prospectus or anysupplement to this prospectus and you should not consider any information on, or that can be accessed through, our website as part ofthis prospectus or any supplement to this prospectus (other than those filings with the SEC that we specifically incorporate by referenceinto this prospectus or any supplement to this prospectus). You may also access these filings at the SEC’s website at www.sec.gov.

Any statement contained ina document incorporated or deemed to be incorporated by reference in this prospectus will be deemed modified, superseded or replaced forpurposes of this prospectus to the extent that a statement contained in this prospectus modifies, supersedes or replaces such statement.

6,497,800Shares of Common Stock

MUSTANG BIO,INC.

PRELIMINARYPROSPECTUS 

,2024 

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 13. Other Expenses of Issuance and Distribution

The following table indicatesthe expenses to be incurred in connection with the offering described in this registration statement, other than underwriting discountsand commissions, all of which will be paid by us. All amounts are estimated except the SEC registration fee.

Item 14. Indemnification of Directors and Officers

Under the General CorporationLaw of the State of Delaware (“DGCL”), a corporation may include provisions in its certificate of incorporation that willrelieve its directors of monetary liability for breaches of their fiduciary duty to the corporation, except under certain circumstances,including a breach of the director’s duty of loyalty, acts or omissions of the director not in good faith or which involve intentionalmisconduct or a knowing violation of law, the approval of an improper payment of a dividend or an improper purchase by the corporationof stock or any transaction from which the director derived an improper personal benefit. The Company’s Amended and Restated Certificateof Incorporation, as amended, eliminates the personal liability of directors to the Company or its stockholders for monetary damages forbreach of fiduciary duty as a director with certain limited exceptions set forth in the DGCL.

Section 145 of the DGCL grantsto corporations the power to indemnify each officer and director against liabilities and expenses incurred by reason of the fact thathe or she is or was an officer or director of the corporation if he or she acted in good faith and in a manner he or she reasonably believedto be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonablecause to believe his or her conduct was unlawful. The Company’s Amended and Restated Certificate of Incorporation, as amended, andAmended and Restated Bylaws, as amended, provide for indemnification of each officer and director of the Company to the fullest extentpermitted by the DGCL. Section 145 of the DGCL also empowers corporations to purchase and maintain insurance on behalf of any person whois or was an officer or director of the corporation against liability asserted against or incurred by him in any such capacity, whetheror not the corporation would have the power to indemnify such officer or director against such liability under the provisions of Section145 of the DGCL.

Item 15. Recent Sales of Unregistered Securities.

Set forth below is informationregarding all securities sold by us since January 1, 2021, the offer and sale of which were not registered under the Securities Act. Alsoincluded is the consideration received by us for such securities and information relating to the section of the Securities Act, or ruleof the SEC, under which exemption from registration was claimed.

October 2023 Private Placement

On October 26, 2023, we enteredinto a Securities Purchase Agreement (the “October 2023 Purchase Agreement”) with an institutional accredited investor, fora private placement offering of warrants to purchase 2,588,236 shares of common stock. Pursuant to the October 2023 Purchase Agreement,we agreed to issue and sell the warrants at an offering price of $0.125 per warrant to purchase one share of common stock (the “October2023 Private Placement Warrants”). The October 2023 Private Placement Warrants have an exercise price of $1.58 per share (subjectto adjustment as set forth in the October 2023 Private Placement Warrants), were exercisable immediately upon issuance and will expirefive and one-half (5.5) years from the date on which the October 2023 Private Placement Warrants become exercisable. The October PrivatePlacement Warrants contain standard anti-dilution adjustments to the exercise price including for share splits, share dividend, rightsofferings and pro rata distributions. This private placement closed on October 30, 2023, concurrently with an offering to the same institutionalaccredited investor that was registered under the Securities Act (the “October 2023 Offerings”). The gross proceeds to usfrom the private placement, before deducting placement agent fees and other estimated offering expenses payable by us, were approximately$0.32 million. H.C. Wainwright & Co., LLC (“Wainwright”) acted as the exclusive placement agent in connection with theprivate placement under an engagement, between us and Wainwright. Pursuant to the engagement letter, Wainwright was paid a cash fee equalto 7.0% of the gross proceeds received by us in the October 2023 Offerings, a management fee equal to 1.0% of the gross proceeds of theOctober 2023 Offering, $75,000 for non-accountable expenses and a clearing fee of $15,950 (the “October 2023 Engagement Letter”).In addition, under the terms of the October 2023 Engagement Letter, we issued to Wainwright (or its designees) warrants to purchase upto 155,294 shares of common stock (the “October 2023 Wainwright Warrants” and together with the October 2023 Private PlacementWarrants, the “2023 Warrants”). The October 2023 Wainwright Warrants have substantially the same terms as the Warrants, exceptthat the October 2023 Wainwright Warrants will expire five (5) years from the commencement of the sales of the October 2023 Offeringsand have an exercise price of $2.125 per share (subject to customary adjustment as set forth in the October 2023Wainwright Warrants).The 2023 Warrants were offered and sold in reliance on the exemption from registration provided by Section 4(a)(2) of the Securities Act.The investor also represented that it qualified as an “accredited investor” within the meaning of Rule 501 of Regulation D.

June 2024 Private Placement

On June 19, 2024, we enteredinto a Purchase Agreement with an institutional accredited investor, for the issuance and sale of Private Placement Warrants to purchaseup to 6,130,000 shares of our common stock. Pursuant to the Purchase Agreement, we agreed to issue and sell the Private Placement Warrantsat an offering price of $0.41 per warrant to purchase one share of common stock. The Private Placement Warrants have an exercise priceof $0.41 per share (subject to adjustment as set forth in the Private Placement Warrants), were exercisable immediately upon issuanceand will expire five and one-half (5.5) years from the date on which the Private Placement Warrants become exercisable. The Private PlacementWarrants contain standard anti-dilution adjustments to the exercise price including for share splits, share dividend, rights offeringsand pro rata distributions. This Private Placement closed on June 21, 2024, concurrently with the Registered Direct Offering with thesame institutional accredited investor that was registered under the Securities Act ). The gross proceeds to us from the Private Placement,before deducting placement agent fees and other estimated offering expenses payable by us, were approximately $2.51 million. Wainwrightacted as the placement agent in connection with the Private Placement pursuant to an engagement agreement, between us and Wainwright.Wainwright was paid a cash fee equal to 7.0% of the gross proceeds received us in the Offerings, a management fee equal to 1.0% of thegross proceeds of the Offerings, $75,000 for non-accountable expenses and a clearing fee of $15,950. In addition, under the terms of theEngagement Letter, we issued to Wainwright (or its designees) Wainwright Warrants to purchase up to 367,800 shares of our common stockThe Wainwright Warrants have substantially the same terms as the Private Placement Warrants, except that the Wainwright Warrants willexpire five (5) years from the commencement of the sales of the Offerings and have an exercise price of $0.5125 per share (subject tocustomary adjustment as set forth in the Wainwright Warrants). The 2024 Warrants were offered and sold in reliance on the exemption fromregistration provided by Section 4(a)(2) of the Securities Act. The investor also represented that it qualified as an “accreditedinvestor” within the meaning of Rule 501 of Regulation D.

Item 16. Exhibits and Financial Statement Schedules

The exhibits listed below are filed as part of this registration statement.

# Portions of this Exhibit have been omitted pursuant to Item601(b)(1)(iv) of Regulation S-K.

† Managementcontract or compensatory plan.

Item 17. Undertakings.

(a) The undersigned registrant hereby undertakes:

Provided, however, that Paragraphs (i),(ii), and (iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphsis contained in reports filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d) of the SecuritiesExchange Act of 1934 that are incorporated by reference in this registration statement;

(b) The undersigned Registrant hereby undertakesthat:

(i) for purposes of determiningany liability under the Securities Act of 1933, the information omitted from the form of prospectus filed as part of this registrationstatement in reliance upon Rule 430A and contained in a form of prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or497(h) under the Securities Act of 1933 shall be deemed to be part of this registration statement as of the time that it was declaredeffective.

(ii) For the purpose of determiningany liability under the Securities Act of 1933, each post-effective amendment that contains a form of prospectus shall be deemed to bea new registration statement relating to the securities offered therein, and the offerings of such securities at that time shall be deemedto be the initial bona fide offering thereof.

SIGNATURES

Pursuant to the requirementsof the Securities Act, the Registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereuntoduly authorized, in Worcester, Massachusetts, on July 19, 2024.

POWER OF ATTORNEY

Each person whose signatureappears below constitutes and appoints each of Manuel Litchman, M.D. and James Murphy, acting alone or together with another attorney-in-fact,as his or her true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for such person and in hisor her name, place and stead, in any and all capacities, to sign any or all further amendments (including post-effective amendments) tothis registration statement (and any additional registration statement related hereto permitted by Rule 462(b) promulgated underthe Securities Act, (and all further amendments, including post-effective amendments, thereto)), and to file the same, with all exhibitsthereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-factand agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be donein and about the premises, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming allthat said attorney-in-fact and agent, or his or her substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirementsof the Securities Act, this Registration Statement has been signed by the following persons in the capacities and on the dated indicated.