KTE-X19 at 1×106 CAR T cells/kg had a high manufacturing success rate and manageable safety that further improved with revised AE management
KTE-X19 resulted in high complete remission rates and undetectable residual disease; median response duration (1×106 dose) was 18 months
ZUMA-3 is a phase 1/2 study evaluating KTE-X19, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in adult relapsed/refractory (R/R) B-ALL. We report the phase 1 results. Following fludarabine/cyclophosphamide lymphodepletion, patients received a single infusion of KTE-X19 at 2, 1, or 0.5×106 cells/kg. The rate of dose-limiting toxicities (DLTs) within 28 days following KTE-X19 infusion was the primary endpoint. KTE-X19 was manufactured for 54 enrolled patients and administered to 45 (median age: 46 years [range, 18-77]). No DLTs occurred in the DLT-evaluable cohort. Grade ≥3 cytokine release syndrome (CRS) and neurologic events (NE) occurred in 31% and 38% of patients, respectively. To optimize the benefit-risk ratio, revised adverse event (AE) management for CRS and NE (earlier steroid use for NE and tocilizumab only for CRS) was evaluated at 1×106 cells/kg KTE-X19. In the 9 patients treated under revised AE management, 33% had grade 3 CRS and 11% had grade 3 NE, with no grade 4/5 NE. The overall complete remission rate correlated with CAR T-cell expansion and was 83% in patients treated with 1×106 cells/kg and 69% in all patients. Minimal residual disease was undetectable in all responding patients. At 22.1 months (range, 7.1-36.1) median follow-up, the median duration of remission was 17.6 months (95% CI, 5.8-17.6) in patients treated with 1×106 cells/kg and 14.5 months (95% CI, 5.8-18.1) in all patients. KTE-X19 treatment provided a high response rate and tolerable safety in adults with R/R B-ALL. Phase 2 is ongoing at 1×106 cells/kg with revised AE management.