Mustang Bio Receives FDA Orphan Drug Designation for MB-101 in Difficult-to-Treat Astrocytomas and Glioblastoma

WORCESTER, Mass. – July 07, 2025 – Mustang Bio, Inc. (Nasdaq: MBIO), a clinical-stage biopharmaceutical company, today announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to MB-101 (IL13Ra2-targeted CAR T-cells) for the treatment of recurrent diffuse and anaplastic astrocytoma (astrocytomas) and glioblastoma (GBM).

This designation applies to drugs intended for rare diseases affecting fewer than 200,000 people in the U.S. and provides incentives such as tax credits, user fee waivers, and seven years of market exclusivity upon approval.

Manuel Litchman, M.D., President and CEO of Mustang, stated, “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.”

Mustang’s novel therapeutic strategy, designated as MB-109, combines MB-101 CAR-T cell therapy with MB-108, an oncolytic virus. The combination is designed to leverage MB-108 to reshape the tumor microenvironment (TME), making “cold” tumors “hot” and thereby potentially improving the efficacy of MB-101 CAR-T cell therapy.

Preclinical and Clinical Evidence:

• Preclinical data presented at AACR 2022 supported this combination approach.
• Separately, MB-101 and MB-108 were well tolerated in recurrent GBM patients.
• A 2024 Nature Medicine paper reported that two patients treated solely with MB-101 who had high levels of intratumoral CD3+ T cells (“hot” tumors) achieved complete responses lasting 7.5 and 66+ months, respectively. These responses were observed in the cohort of three patients with the “hottest” tumors prior to MB-101 treatment.

Phase 1 clinical trials for MB-101 at City of Hope and MB-108 at The University of Alabama at Birmingham continue to enroll patients. The company’s ability to further develop the MB-109 program is contingent on securing additional funding or a strategic partnership.