Impact of pre-infusion disease burden on outcomes in pediatric relapsed/refractory B-cell lymphoblastic leukemia following anti-CD19 CAR T-cell therapy

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have demonstrated high efficacy in pediatric patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Despite this success, the challenge of post-infusion relapse persists. In our study, we evaluate 116 children with R/R B-ALL who received anti-CD19 CAR T-cell therapy at our center. All patients were included in the response analysis and assessed for survival and toxicity. The CR rate was 98.3%, with 90.5% achieving minimal residual disease negative (MRD)^- CR by day 28 (d28). The overall survival (OS) and event-free survival (EFS) were 69.3%±4.5% and 59.0%±4.6%, respectively, with a median follow-up duration of 47.9 months. The patients with pre-infusion MRD ≥ 1% was associated with lower 4-year OS (<i>p</i> = 0.006) and EFS (<i>p</i> = 0.027) comparing to those with MRD < 1%. The incidences of grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity were21.6 and 5.0%, respectively. Therefore, pre-infusion disease burden is a predictor of long-term outcome following anti-CD19 CAR T-cell therapy for pediatric R/R B-ALL.