Mustang Bio, Inc. has been granted Orphan Drug Designation by the U.S. Food and Drug Administration (FDA) for MB-108, a herpes simplex virus type 1 (HSV-1) oncolytic virus, for the treatment of malignant glioma. This designation aims to encourage the development of therapies for rare diseases affecting fewer than 200,000 people in the U.S.
The FDA's Orphan Drug Designation provides Mustang Bio with incentives, including tax credits for clinical trial costs and prescription drug user fee waivers. If MB-108 receives FDA approval, the company is entitled to seven years of market exclusivity for the treatment of malignant glioma.
Significance of Orphan Drug Designation
Manuel Litchman, M.D., President and Chief Executive Officer of Mustang, stated, "The Orphan Drug Designation for MB-108 is significant for Mustang, as it could provide additional market exclusivity, and we hope to advance MB-108, in combination with MB-101, as a potential treatment option for patients living with malignant glioma, including patients with recurrent glioblastoma (GBM) and high-grade astrocytomas, where there is historically a median overall survival of six months."
MB-108 and Combination Therapy
MB-108 is currently in Phase 1 clinical trials and has demonstrated activity and tolerability in patients with recurrent glioblastoma. Preclinical data supports a novel combination of MB-108 and MB-101 (IL13Rα2-targeted CAR-T cell therapy) to optimize clinical results. The combination leverages MB-108 to reshape the tumor microenvironment (TME) and make cold tumors “hot,” thereby potentially improving the efficacy of MB-101 CAR-T cell therapy.
Clinical Data and Ongoing Trials
Data presented at the American Association for Cancer Research (AACR) Annual Meeting in 2022 showed that MB-101 was well-tolerated in recurrent GBM patients. Two patients treated solely with MB-101 who had high levels of intratumoral CD3+ T cells pre-therapy achieved complete responses lasting 7.5 and 31+ months, respectively. 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.
Future Development
Mustang Bio plans to request Orphan Drug Designation from the FDA for MB-101 (IL13Rα2-targeted CAR-T cell therapy) in malignant gliomas. 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.
