Mustang Bio to present MB-106 CD20-targeted CAR-T data

Mustang Bio announced that interim Phase 1/2 data from Mustang’s multicenter clinical trial of MB-106, a CD20-targeted, autologous CAR-T cell therapy for patients with relapsed or refractory B-cell non-Hodgkin lymphomas and chronic lymphocytic leukemia, have been selected for a poster presentation at the 65th American Society of Hematology Annual Meeting, taking place December 9-12, 2023 in San Diego. MB-106 is being developed in a collaboration between Mustang and Fred Hutchinson Cancer Center. The abstract posted today on the ASH Annual Meeting website reported on four patients who received MB-106 at dose level 1, 3.3106 cells/kg: two patients with follicular lymphoma who achieved complete response as demonstrated by both PET-CT and bone marrow biopsy, one patient with Waldenstrom macroglobulinemia who achieved a very good partial response and one patient with transfusion-dependent hairy cell leukemia variant who continued to have stable disease with decreased bone marrow disease and who achieved complete transfusion independence which is ongoing at 6 months. All patients displayed MB-106 expansion, with peak levels between 7-14 days post-infusion, and CAR-T cell persistence is ongoing at 6 months. From a safety perspective, 3 patients experienced Grade 1 cytokine release syndrome and no occurrences of immune effector cell-associated neurotoxicity syndrome were reported. Dose-limiting toxicities were monitored through day 28, and no DLTs were observed at DL1. Because of this favorable safety profile, MB-106 is infused in the outpatient setting if allowed by the institution, except for the first patient in each DL cohort, who is kept for overnight observation after MB-106 administration. All four patients were heavily pre-treated, with a median of 5.5 prior lines of treatment. The WM patient in particular had nine prior treatments, including autologous stem cell transplant, and a high disease burden, and the patient’s VGPR was notable for complete metabolic response by PET-CT, morphologic clearance of lymphoma in bone marrow and resolution of the immunoglobulin M paraprotein. Other high-risk features were observed in each of the two FL patients: progression of disease within 24 months of first-line treatment in one patient and prior CD19-targeted CAR-T therapy in the other. Finally, the HCL-v patient received non-conforming material following FDA authorization.