Background
Phase 2, multicenter, single-arm registration trial (ZUMA-3, NCT03761056). N=78 adults (≥18 years) with R/R B-cell ALL; 55 treated after successful CAR-T manufacturing. Heavily pretreated (median 2 prior lines; 45% had prior allo-HSCT). Brexucabtagene autoleucel (KTE-X19, TECARTUS) is an autologous CD28ζ anti-CD19 CAR-T product; it differs from tisagenlecleucel by (1) a manufacturing process that removes circulating CD19+ blasts, and (2) inclusion of adults. FDA approved October 2021. Published Lancet 2021; 3-year analysis Leukemia 2025.
Interventions and follow up
Regimen: Brexucabtagene autoleucel (KTE-X19) 1 × 10⁶ CAR-T cells/kg IV single infusion after fludarabine/cyclophosphamide lymphodepletion in adult R/R B-ALL
Primary endpoint: CR + CRi rate (complete remission with incomplete hematologic recovery)
mFollow up: 41.6 months (3-year analysis)
Primary endpoint: CR + CRi rate (complete remission with incomplete hematologic recovery)
mFollow up: 41.6 months (3-year analysis)
Results
CR/CRi rate (primary, N=55 treated): 71% (39/55); CR 60% (33/55)
MRD-negative (among treated): 76%; among responders 97%
mRFS (all treated): 11.6 months
mOS (all treated): 25.4 months (3-year update; initial report 18.2 months)
mOS (CR/CRi responders): Not reached at 3-year analysis
3-year OS: ~47%
Manufacturing success rate: 92% (65/71)
MRD-negative (among treated): 76%; among responders 97%
mRFS (all treated): 11.6 months
mOS (all treated): 25.4 months (3-year update; initial report 18.2 months)
mOS (CR/CRi responders): Not reached at 3-year analysis
3-year OS: ~47%
Manufacturing success rate: 92% (65/71)
Adverse events
CRS: Grade ≥3 CRS 24%; any-grade CRS 89%
Neurologic (ICANS): Grade ≥3 25%; any-grade 60%
Hematologic/infectious: Prolonged grade ≥3 cytopenias ~60%; grade ≥3 infections 27%
Deaths/second malignancy: 2 treatment-related deaths (1 CRS, 1 neurotoxicity); FDA 2024 boxed warning for secondary T-cell malignancy applies to all CAR-T products
Neurologic (ICANS): Grade ≥3 25%; any-grade 60%
Hematologic/infectious: Prolonged grade ≥3 cytopenias ~60%; grade ≥3 infections 27%
Deaths/second malignancy: 2 treatment-related deaths (1 CRS, 1 neurotoxicity); FDA 2024 boxed warning for secondary T-cell malignancy applies to all CAR-T products
Conclusions
Brexucabtagene autoleucel achieved 71% CR/CRi in adult R/R B-ALL with 97% MRD-negativity among responders. With mOS of 25.4 months in a population that historically had median survival <6 months, this represents a transformative improvement. A durable long-term remission plateau (~30–40% at 3–5 years) suggests curative potential in a subset.
Key Limitations
Single-arm design without randomized comparator. High grade ≥3 CRS (24%) and neurotoxicity (25%) require specialized infrastructure and limit applicability to fit patients. Substantial attrition between enrollment (78) and treatment (55) due to manufacturing time and disease progression. mRFS of 11.6 months indicates frequent relapse. Small sample size limits subgroup precision.
Clinical Context
ZUMA-3 supported the FDA approval (October 2021) of brexucabtagene autoleucel for adults with R/R B-ALL — the first CAR-T approved for adult ALL; EMA approval followed. ASCO and ESMO guidance recognize CD19 CAR-T as a standard option for adult R/R B-ALL, with choice among brexu-cel and obecabtagene autoleucel guided by toxicity profile and access.