Long-term treatment with the chimeric antigen receptor (CAR) T-cell therapy KTE-X19 was shown to be safe and effective in pediatric and adolescent patients with relapsed or refractory B-cell acute lymphocytic leukemia (B-ALL), according to study results presented at the 2021 American Society of Pediatric Hematology/Oncology (ASPHO) meeting.

Phase 1 of the multicenter, single‑arm, open‑label ZUMA‑4 study (ClinicalTrials.gov Identifier NCT02625480) included 24 patients aged 21 years and younger with relapsed or refractory B-ALL. The primary endpoint for the study was the incidence of dose-limiting toxicities (DLTs). Patients were assigned to 3 different dose levels: 2×106 cells/kg (n=4), 1×106 cells/kg (68 mL; n=11), and 1×106 cells/kg (40 mL; n=9).

The median follow up was 36.1 (range, 24.0-53.9) months. The median time from leukapheresis to KTE‑X19 release was 14.0 days for all treated patients, 16.5 days from leukapheresis to delivery to study site, and 27.0 days from leukapheresis to infusion.

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In the overall patient population, grade 3 or higher adverse events (AEs) occurred in all patients and consisted of mostly hypotension (50%) and anemia (42%). A total of 88% of patients experienced cytokine release syndrome (CRS), with 33% of patients experiencing grade 3 CRS. There was no grade 4 or higher CRS events, and all CRS events resolved.

Improved overall safety was observed in patients treated with the 1×106 CAR T-cells/kg (40 mL) dose under revised toxicity management compared with patients treated with 2×106 CAR T-cells/kg or 1×106 CAR T-cells/kg (68 mL).

The complete remission (CR) rates were 75%, 64%, and 67% in the 2×106 cells/kg, 1×106 cells/kg (68-mL), and 1×106 cells/kg (40-mL) groups, respectively. Of responding patients, 100% had undetectable minimal residual disease. At the time the study concluded, median overall survival was not reached.

Phase 2 of the ZUMA-4 trial is currently enrolling pediatric patients with relapsed or refractory B-ALL or non-Hodgkin lymphoma, including patients who have minimal residual disease-positive disease and early relapse after frontline therapy.

Disclosure: Several study authors declared affiliations with the biotech or pharmaceutical industries. Please see the original reference for a full list of authors’ disclosures.


Wayne AS, Huynh V, Hijiya N, et al. ZUMA-4 phase 1 long-term results: KTE-X19 CAR T-cell therapy in children/adolescents with R/R B-ALL. Poster presented at: 2021 American Society of Pediatric Hematology/Oncology virtual meeting; April 21-23, 2021.