Obe-cel provides consistent efficacy and safety for relapsed or refractory B-ALL regardless of EMD status

In the phase 1b/2 FELIX trial, treatment with obecabtagene autoleucel (obe-cel) yielded favorable safety and efficacy outcomes for patients with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL), regardless of extramedullary disease (EMD) status at time of lymphodepletion. Duration of response (DoR) was comparable between responders with or without EMD.

Jae H Park, MD, of Memorial Sloan Kettering Cancer Center in New York, and colleagues presented the findings at the Fourteenth Annual Meeting of the Society of Hematologic Oncology in Houston, Texas.

The FELIX study administered obe-cel, an autologous chimeric antigen receptor T-cell therapy, to patients with relapsed or refractory B-ALL using a tumor burden–guided dosing strategy. Out of 127 patients that received obe-cel infusion, 21% had EMD at lymphodepletion. The median bone marrow blast percentage at lymphodepletion was 54% in patients with EMD and 39% in patients without EMD.

After a median follow-up of 32.8 months (range, 19.9-52.8), the overall remission rate was 59% (95% CI, 39-78) in patients with EMD and 83% (95% CI, 74-90) in patients without EMD. Among responders, the median DoR was 42.5 months (95% CI, 3.4-not evaluable [NE]) for 16 responders with EMD and NE for 83 responders without EMD.

The overall median event-free survival (EFS) was 4.5 months (95% CI, 0-NE) in patients with EMD and 14.3 months (95% CI, 9-NE) in patients without EMD. However, median EFS between responders with and without EMD was comparable at 44.6 months (95% CI, 6-NE) and NE, respectively, according to the authors. The median overall survival was 15.3 months (95% CI, 7.85-NE) for patients with EMD and 21 months (95% CI, 13.2-NE) for patients without EMD.

The rates of grade 3 or higher cytokine release syndrome were 3.7% and 19% and rates of grade 3 or higher immune effector cell-associated neurotoxicity syndrome were 2% and 4% for patients with and without EMD, respectively.

Reference

Park JK, Sandhu KS, Roddie C, et al. The effect of obecabtagene autoleucel on adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia and extramedullary disease. Abstract ALL-77. Presented at the 2026 Society of Hematologic Oncology Annual Meeting; September 9-12, 2026; Houston.