Mustang Bio announces efficacy, safety data from WM cohort of Phase 1/2 trial

Mustang Bio announced that updated data from the ongoing Phase 1/2 clinical trial of MB-106, a CD20-targeted, autologous CAR T-cell therapy, show a favorable safety and efficacy profile in patients with Waldenstrom macroglobulinemia a rare form of blood cancer. MB-106 is being developed in a collaboration between Mustang and Fred Hutch Cancer Center to treat patients with relapsed or refractory B-cell non-Hodgkin lymphomas and chronic lymphocytic leukemia. The updated results from the single-institution Phase 1/2 clinical trial were presented during a poster session at the European Hematology Association 2024 Hybrid Congress by Brian Till, M.D., Associate Professor and physician at Fred Hutch and University of Washington. All ten patients in the study were previously treated with Bruton’s tyrosine kinase inhibitors, and their disease continued to progress while on BTKi. Overall, 90% of the patients treated with MB-106 responded to treatment, including 3 complete responses, 2 very good partial responses and 4 partial responses. In addition, 1 patient experienced stable disease. One of the patients who achieved a complete response has remained in remission for 31 months, with an immunoglobulin M level that decreased rapidly to the normal range after treatment with MB-106 and has remained normal since. Patients had a median of nine prior lines of therapy and only one patient has started additional anti-WM treatment after being treated with MB-106. From a safety perspective, cytokine release syndrome occurred in nine patients: five patients with grade 1 and four patients with grade 2. One patient experienced grade 1 immune effector cell-associated neurotoxicity syndrome. No grade 3 or 4 CRS or grade 2, 3 or 4 ICANS has been observed, despite dose escalation.