Mustang Bio Inc (NASDAQ:MBIO) stock soared over 78% following the U.S. Food and Drug Administration’s orphan drug designation for its MB-101 therapy targeting recurrent diffuse and anaplastic astrocytoma and glioblastoma—rare and aggressive brain cancers.
The designation offers Mustang Bio benefits such as clinical trial tax credits and seven years of market exclusivity upon approval. The FDA’s scope for the designation is broader than Mustang’s initial proposal.
MB-101 is a CAR T-cell therapy engineered to target IL13Ra2 receptors on these tumors. In a Phase 1 trial published in Nature Medicine, 50% of patients experienced stable disease or better, with two patients achieving complete responses lasting 7.5 months and over 66 months, respectively.
The trial involved 57 patients, with the two complete responders coming from a subgroup of three patients exhibiting the highest levels of intratumoral CD3+ T cells prior to treatment.
Mustang Bio is also advancing MB-109, a combination therapy pairing MB-101 with MB-108, an oncolytic virus treatment that previously received orphan designation for malignant glioma. MB-108 is intended to alter the tumor microenvironment to boost MB-101’s efficacy.
Further development of MB-109 depends on additional funding or a strategic partnership. Mustang Bio licenses MB-101 from City of Hope and MB-108 from Nationwide Children’s Hospital. Phase 1 trials for both therapies are ongoing at City of Hope and the University of Alabama at Birmingham.