CAR T-cell therapy as a definitive consolidation for older adults with B-ALL in first complete remission

We report a phase 1 study assessing the safety and efficacy of CD19 chimeric antigen receptor (CAR) T cells as definitive consolidation in older adults (aged ≥55 years) with B-cell acute lymphoblastic leukemia (B-ALL) in first complete remission (CR1). Eighteen patients received lymphodepletion followed by infusion of memory-enriched CD19 CAR T cells. The median age was 64 years, and all patients were measurable residual disease (MRD)-negative before lymphodepletion. There were no dose-limiting toxicities, grade ≥2 cytokine release syndrome, or any grade immune effector cell-associated neurotoxicity syndrome. Estimated 18-month event-free and overall survival were 84% and 100%, respectively. CAR T cells expanded in the blood and cerebrospinal fluid despite patients' MRD-negative status. Comparing clinical samples from patients with relapsed/refractory (R/R) B-ALL from our historical trial (ClinicalTrials.gov identifier: NCT02146924) and patients in CR1, we found that the blood and CAR T-cell products from patients with R/R B-ALL were hyperinflammatory and hyperimmunometabolic, respectively. First-line CAR T-cell therapy was safe and well tolerated and potentially extended remission in patients in MRD-negative CR1. These findings support further investigation of the early use of CAR T-cell therapy for B-ALL. This trial was registered at www.clinicaltrials.gov as NCT05707273.