Multinational phase 1-2 study of obecabtagene autoleucel for B-cell acute lymphoblastic leukemia in adult patients

Obecabtagene autoleucel (obe-cel) is an autologous 41BB-ζ anti-CD19 CAR T-cell therapy which uses an intermediate-affinity CAR to reduce toxic effects and improve persistence. The multinational phase 1b-2 FELIX study evaluated obe-cel for relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) in adult patients. Overall remission occurred in 77% of patients. The median event-free survival was 11.9 months (95% CI 8.0-22.1) with 6-month EFS rate 65.4% and 12-month EFS rate 49.5%. The median overall survival was 15.6 months (95% 12.9-NE) with 6-month OS rate 80.3% and 12-month OS rate 61.1%. Grade 3 or higher cytokine release syndrome was seen in 2.4% of the patients and grade 3 or higher immune effector cell-associated neurotoxicity syndrome in 7.1%. The authors conclude that obe-cel had durable activity among adult patients with R/R B-ALL, with a low incidence of grade 3 or higher immune-related toxic effects.