[Long-term safety and activity of humanized CD19 chimeric antigen receptor T cells for children and young adults with relapsed/refractory acute lymphoblastic leukemia].

To investigate the efficacy and safety of humanized CD19-specific chimeric antigen receptor T cells (hCART19s) in treating children and young adults with relapsed/refractory acute lymphoblastic leukemia (R/R ALL) and to analyze relevant factors affecting its curative effect and prognosis. We conducted a single-center clinical trial involving 31 children and young adult patients with R/R B-ALL who were treated with humanized CD19-specific CAR-T cells (hCART19s) from May 2016 to September 2021. Results showed that 27 (87.1%) patients achieved complete remission (CR) or CR with incomplete count recovery (CRi) one month after CAR-T cell infusion. During treatment, 20 (64.5%) patients developed grade 1-2 cytokine release syndrome (CRS) , and 4 (12.9%) developed grade 3 CRS. Additionally, two patients had grade 1 neurological events. During the follow-up with a median time of 19.3 months, the median event-free survival (EFS) was 15.7 months (95% 8.7-22.5) , and the median overall survival (OS) was 32.2 months (95% 10.6-53.9) . EFS and OS rates were higher in patients who have undergone hemopoietic stem cell transplantation (HSCT) than in those without [EFS: (75.0 ± 12.5) % (21.1 ± 9.4) %, =0.012; OS: (75.0 ± 12.5) % (24.6 ± 10.2) %, =0.035]. The EFS and OS rates were significantly lower in patients with >3 treatment lines than in those with <3 treatment lines [EFS: 0 (49.5±10.4) %, <0.001; OS: 0 (52.0±10.8) %, <0.001]. To the cutoff date, 12 patients presented with CD19(+) relapse, and 1 had CD19(-) relapse. hCART19s are effective in treating pediatric and young adult R/R ALL patients, with a low incidence of severe adverse events and reversible symptoms. Following HSCT, the number of treatment lines can affect the long-term efficacy and prognosis of pediatric and young adult R/R ALL patients.