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Mustang Bio Initiates Cell Therapy Trial in Patients With CD123-Positive Blood Cancers

NEW YORK – Worcester, Massachusetts-based Mustang Bio on Thursday announced that the first patient has been dosed in a Phase I/II clinical trial evaluating Mustang's investigational CD123-targeted CAR T cell therapy MB-102, a treatment for patients with relapsed or refractory blastic plasmacytoid dendritic cell neoplasm (BPDCN), acute myeloid leukemia, and high-risk myelodysplastic syndrome (hrMDS).

In the Phase I portion of the trial, investigators will assess the maximum tolerated dose of MB-102, and in the Phase II portion, they will evaluate the treatment's efficacy across three separate arms, stratified according to the type of malignancy. The primary aim of the Phase II portion will be to assess patients' response rates 28 days after they received the cell therapy infusion. The trial's secondary outcomes include patients' duration of response, progression-free survival, overall survival, and treatment-emergent adverse events.

The trial expects to enroll 126 participants, all of whom must have confirmed CD123 positivity on their bone marrow. The investigational therapy that these patients will receive, MB-102, consists of patients' own T cells that are genetically modified to express a CD123-specific, CD28-costimulatory chimeric antigen receptor, as well as a truncated EGFR receptor. Patients' T cells will be derived by leukapheresis following initial treatment with chemotherapy to deplete patients' immune systems in preparation for the infusion of the engineered cells.

In an initial first-in-human clinical trial of the cell therapy — in which the treatment patients received was derived from either their own cells or a donor's cells — low doses of MB-102 resulted in complete responses among several patients with AML and BPDCN without dose-limiting toxicities.

"This is a momentous occasion for Mustang, as it is the first clinical trial under Mustang's investigational new drug application in which a patient was dosed with cells processed in our own manufacturing facility," Manuel Litchman, Mustang's president and CEO, said in a statement. "We look forward to advancing the development of MB-102 and providing updates on the trial as we seek to help address the needs of patients suffering from the devastating diseases of BPDCN, AML, and hrMDS."