Mustang Bio Receives Orphan Drug Designation for Investigational CAR T-Cell Therapy for AML

Mustang Bio announced Wednesday that FDA has granted Orphan Drug Designation to MB-102, an investigational chimeric antigen receptor (CAR) T-cell therapy that is being studied for the treatment of acute myeloid leukemia (AML). The FDA had previously granted Orphan Drug Designation to MB-102 for the treatment of blastic plasmacytoid dendritic cell neoplasm (BPDCN).

MB-102, also known as CD123 CAR T, is engineered using a patient’s T cells to recognize and eliminate CD123-expressing tumors. CD123, a molecule that helps transmit interleukin-3, is a key biomarker and treatment target for patients with myelodysplastic syndromes and several types of hematologic malignancies, including AML and BPDCN. These patients express CD123 in bone marrow cells (CD123 is also expressed in of B-cell acute lymphoblastic leukemia, hairy cell leukemia, BPDCN, chronic myeloid leukemia and Hodgkin’s lymphoma.)

According to a statement from Mustang, the investigational treatment has demonstrated complete responses in patients with AML in low doses during first-in-human clinical trial at City of Hope, with these results reported at the 2017 meeting of the American Society of Hematology and the American Association of Cancer Research Special Conference on Tumor Immunology and Immunotherapy in November 2018. The statement said dose escalation studies are ongoing at City of Hope.

“We are pleased that MB-102 has received Orphan Drug Designation in two indications, AML and BPDCN,” Manuel Litchman, MD, president and chief executive officer of Mustang, said in a statement. “AML most commonly occurs in senior adults, many of whom have to forgo chemotherapy due to other health conditions. MB-102 has the potential to be an important new treatment for these and other patients, and to potentially address multiple areas of high unmet medical need. We expect to initiate a multicenter phase 1/2 clinical trial in patients with AML, BPDCN and high-risk myelodysplastic syndrome in the coming months.”

MB-102 is currently being studied in a City of Hope, first-in-human Phase 1 dose-escalation clinical trial evaluating the safety and anti-tumor activity of escalating doses of MB-102 in patients with relapsed or refractory AML (cohort 1) and BPDCN (cohort 2). Patients receive a single dose of MB-102 with an option for a second infusion if they continue to meet safety and eligibility criteria and still have CD123+ disease. MB-102 has demonstrated complete responses at low doses in AML and BPDCN without dose-limiting toxicities. City of Hope developed CD123 CAR T.

FDA’s Orphan Drug Designation is applied to drugs that affect fewer than 200,000 people in the United States. The designation offers tax credits toward the cost of clinical trials and prescription drug use fee waivers. If approved under this status, the drug gains 7 years of market exclusivity.