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 accelerate the development of treatments for rare diseases affecting fewer than 200,000 people in the U.S.
The FDA's Orphan Drug Designation provides Mustang Bio with several key benefits, including tax credits for clinical trial costs and prescription drug user fee waivers. Furthermore, if MB-108 receives FDA approval, it will be granted seven years of market exclusivity for the treatment of malignant glioma.
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.”
Novel Therapeutic Strategy
Mustang Bio is exploring a novel therapeutic strategy combining MB-108 with MB-101, an IL13Rα2-targeted CAR-T cell therapy. Preclinical data presented at the American Association for Cancer Research (AACR) Annual Meeting in 2022 suggested that MB-108 could reshape the tumor microenvironment (TME), potentially enhancing the efficacy of MB-101 CAR-T cell therapy. The company plans to request Orphan Drug Designation from the FDA for MB-101 in malignant gliomas.
MB-108 is designed to infect tumor cells, leading to the recruitment of endogenous CD8- and CD3-positive effector T-cells, effectively turning “cold” tumors “hot”. This inflamed TME may then permit MB-101 CAR-T cells to better infiltrate the tumor mass, undergo activation, and kill tumor cells. Clinical trials of MB-101 at City of Hope and MB-108 at The University of Alabama at Birmingham are ongoing.
Clinical Data
Clinical data has shown that MB-108 is active and well-tolerated in patients with recurrent glioblastoma in an ongoing Phase 1 clinical trial. Data presented separately on MB-101 and MB-108 showed that administration of these therapies 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 (i.e., “hot” tumors) achieved complete responses lasting 7.5 and 31+ months, respectively. Of the 53 City of Hope Phase 1 patients disclosed at AACR in 2022, these 2 complete responses were observed in the 2 patients with the “hottest” tumors prior to treatment with MB-101.
About MB-109
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).
