Mustang Bio Granted Orphan Drug Designation by U.S. FDA for MB-101 (IL13Ra2-targeted CAR T-cells) to Treat Astrocytomas and Glioblastoma

In an ongoing Phase 1 trial published in Nature Medicine, MB-101 was well-tolerated and 50% of patients achieved stable disease or better with two partial responses and two complete responses lasting 7.5 and 66+ months, respectively

Preclinical data support a novel combination of MB-101 (IL13Rα2‐targeted CAR-T cell therapy) and MB-108 (HSV-1 oncolytic virus) to optimize clinical results

FDA previously granted Orphan Drug Designation to Mustang for MB-108 for the treatment of malignant glioma

WORCESTER, Mass., July 07, 2025 (GLOBE NEWSWIRE) -- Mustang Bio, Inc. (“Mustang” or the “Company”) (Nasdaq: MBIO), a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell therapies into potential cures for difficult-to-treat cancers, today announced that the U.S. Food and Drug Administration (“FDA”) has granted Orphan Drug Designation to Mustang for MB-101 (IL13Ra2-targeted CAR T-cells) for the treatment of recurrent diffuse and anaplastic astrocytoma (astrocytomas) and glioblastoma (GBM).

The FDA grants Orphan Drug Designation to drugs and biologics that are intended for safe and effective treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the U.S. Orphan Drug Designation provides certain incentives, such as tax credits toward the cost of clinical trials upon approval and prescription drug user fee waivers. If a product receives Orphan Drug Status from the FDA, that product is entitled to seven years of market exclusivity for the disease in which it has Orphan Drug designation, which is independent from intellectual property protection.

Manuel Litchman, M.D., President and Chief Executive Officer of Mustang, said, “We are thrilled that MB-101 received Orphan Drug Designation on time and with a designation that is broader than the indication proposed. The Orphan Drug Designation for MB-101, coupled with the Orphan Drug Designation granted previously for MB-108, is strong validation for our science, as we hope to advance MB-101, in combination with MB-108, as a potential treatment option for patients living with malignant glioma, including patients with recurrent glioblastoma (“GBM”) and high-grade astrocytomas. Our novel therapeutic strategy, combining our MB-101 CAR-T cell therapy with our MB-108 oncolytic virus, leverages MB-108 to reshape the tumor microenvironment (“TME”) to make cold tumors “hot,” thereby potentially improving the efficacy of MB-101 CAR-T cell therapy. This progress demonstrates our dedication to exploring new possibilities for improving outcomes in patients with challenging-to-treat cancers.”

As previously reported, preclinical data presented at the American Association for Cancer Research (“AACR”) Annual Meeting in 2022 supported a combination therapy to potentially optimize results to treat recurrent GBM. The combination leverages MB-108 to reshape the TME and make cold tumors “hot,” thereby potentially improving the efficacy of MB-101 CAR-T cell therapy. Data presented separately on MB-101 and MB-108 showed that administration of these therapies was well tolerated in recurrent GBM patients. As reported in City of Hope’s 2024 Nature Medicine paper, 2 patients treated solely with MB-101 who had high levels of intratumoral CD3+ T cells pre-therapy (i.e., “hot” tumors) achieved complete responses lasting 7.5 and 66+ months, respectively. Importantly, of the 57 City of Hope Phase 1 patients evaluable for survival in that paper, these 2 complete responses were observed in the cohort of 3 patients with the “hottest” tumors prior to treatment with MB-101. Phase 1 clinical trials of MB-101 at City of Hope and of MB-108 at The University of Alabama at Birmingham continue to enroll patients.

The Company’s ability to further develop the MB-109 program for recurrent GBM and high-grade astrocytomas is contingent upon raising additional funding and / or consummating a strategic partnership.

About MB-109 (MB-101 (IL13Rα2 targeted CAR-T cells) + MB-108 oncolytic virus) 

MB-109 is Mustang’s designation for the treatment regimen combining MB-101 (IL13Rα2‐targeted CAR-T cell therapy licensed from City of Hope) with MB-108 (HSV-1 oncolytic virus licensed from Nationwide Children’s Hospital). The combination is designed to leverage MB-108 to make cold tumors “hot” and potentially improve the efficacy of MB-101 CAR-T cell therapy. MB-108 oncolytic virus is first injected to infect tumor cells which, in turn, leads to reshaping of the TME through recruitment of endogenous CD8- and CD3-positive effector T-cells. This inflamed TME potentially permits MB-101 CAR-T cells injected into and around the tumor to better infiltrate into and throughout the tumor mass, undergo activation and, ideally, effect tumor cell killing.

About Mustang Bio

Mustang Bio, Inc. is a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell therapies into potential cures for difficult-to-treat cancers. Mustang aims to acquire rights to these technologies by licensing or otherwise acquiring an ownership interest, to fund research and development, and to outlicense or bring the technologies to market. Mustang has partnered with top medical institutions to advance the development of CAR-T therapies. Mustang’s common stock is registered under the Securities Exchange Act of 1934, as amended, and Mustang files periodic reports with the U.S. Securities and Exchange Commission (“SEC”). Mustang was founded by Fortress Biotech, Inc. (Nasdaq: FBIO). For more information, visit .

Forward-Looking Statements

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Company Contacts:

Jaclyn Jaffe and Nicole McCloskey

Mustang Bio, Inc.

(781) 652-4500