As filed with the Securities and Exchange Commission on April 2, 2024. Registration No. 333-278006 UNITED STATES SECURITIES AND EXCHANGE COMMISSION MUSTANG BIO, INC. Amendment No. 1 to FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 2836 (Primary Standard Industrial Classification Code Number) Washington, D.C. 20549 47-3828760 (I.R.S. Employer Identification Number) ...

MUSTANG BIO, INC. (Exact name of registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) As filed with the Securities and Exchange Commission on March 15, 2024. Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 2836 (Primary Standard Industrial Classification Code Number) 47-3828760 (I.R.S. Employer Identification Number) 377 Plantation Street W ...

Financial Performance - As of December 31, 2023, Mustang's cash and cash equivalents totaled $7.0 million, a decrease of $69.7 million from $76.7 million as of December 31, 2022[6]. - Net loss attributable to common stockholders was $51.6 million, or $6.00 per share, for the year ended December 31, 2023, compared to a net loss of $77.5 million, or $10.09 per share, for 2022[6]. - Total assets decreased from $92,422,000 in 2022 to $17,742,000 in 2023, a decline of approximately 81.8%[16]. - Total liabilities reduced significantly from $46,149,000 in 2022 to $17,619,000 in 2023, a decrease of about 61.8%[16]. - Operating expenses for 2023 were $49,260,000, down from $76,159,000 in 2022, representing a reduction of approximately 35.4%[18]. - Net loss for 2023 was $51,602,000 compared to a net loss of $77,525,000 in 2022, indicating an improvement of approximately 33.4%[18]. - Net loss per common share improved from $10.09 in 2022 to $6.00 in 2023[18]. - Cash and cash equivalents decreased from $75,656,000 in 2022 to $6,234,000 in 2023, a decline of approximately 91.8%[16]. - Total stockholders' equity fell from $46,273,000 in 2022 to $123,000 in 2023, a decrease of about 99.7%[16]. - Interest expense increased from $3,359,000 in 2022 to $4,109,000 in 2023, an increase of approximately 22.3%[18]. Research and Development - Research and development expenses for the year ended December 31, 2023, were $40.5 million, down from $62.5 million in 2022[6]. - Research and development expenses decreased from $62,475,000 in 2022 to $40,513,000 in 2023, a decline of about 35.2%[18]. - Mustang reported a 100% overall response rate in patients treated with MB-106 (n=9) for follicular lymphoma (FL) and Waldenstrom macroglobulinemia (WM) in a recent clinical trial[8]. - The FDA granted Orphan Drug Designation to MB-106 for the treatment of WM, with pivotal Phase 2 patient treatment expected in 2024[8]. - Mustang plans to initiate a Phase 1 multicenter clinical trial for MB-109, a combination therapy for recurrent glioblastoma, in 2024[9]. - Mustang aims to request Regenerative Medicine Advanced Therapy (RMAT) designation for indolent lymphoma from the FDA in the first half of 2024[2]. - The company anticipates the publication of proof-of-concept research for its in vivo CAR-T technology platform in 2024[10]. - In 2024, the first patients are expected to be treated in new trials for X-Linked Severe Combined Immunodeficiency (XSCID) using MB-117 and MB-217[11]. Capital Raising - Mustang completed a registered direct offering in October 2023, raising approximately $4.4 million in gross proceeds[6].

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2023 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Transition Period from to . Commission File No. 001-38191 MUSTANG BIO, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 47-3828760 (State or Other Jurisdiction ...

Mustang Bio, Inc. As filed with the Securities and Exchange Commission on December 11, 2023. 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 (Exact name of registrant as specified in its charter) (State or Other Jurisdiction of Incorporation or Organization) Delaware 2834 47-3828760 (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification Number) 377 Planta ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38191 MUSTANG BIO, INC. (Exact name of registrant as specified in its charter) Delaware 47-3828760 (State or other ju ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38191 MUSTANG BIO, INC. (Exact name of registrant as specified in its charter) Delaware 47-3828760 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) 377 Plantation Street For the quarterly period ended June 30, ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38191 MUSTANG BIO, INC. (Exact name of registrant as specified in its charter) Delaware 47-3828760 (State or other jurisd ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Fiscal Year Ended December 31, 2022 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the Transition Period from to . Commission File No. 001-38191 MUSTANG BIO, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 47-3828760 (State or Other Jurisdiction ...

MB-207 for previously transplanted XSCID (IL2RG) MB-101 CAR-T for GBM (IL13Rα2) Combination CAR-T + oncolytic virus (OV) Expect MB-109 Mustang IND filing 2023 UAB MB-108 Phase 1 ongoing* | --- | --- | --- | --- | --- | --- | --- | --- | --- | |-------|----------------------------------------------------------|-----------------------------------------------------------------------------|----------------------------------------------------------|----------------------------------------------------------|----- ...