Long-term response to autologous anti-CD19 chimeric antigen receptor T cells in relapsed or refractory B cell acute lymphoblastic leukemia: a systematic review and meta-analysis

Chimeric Antigen Receptor (CAR) T cell therapy is an effective treatment approach for patients with relapsed or refractory acute lymphoblastic leukemia (R/R B-ALL). However, identifying the factors that influence long-term response to this therapy is necessary to optimize patient selection and treatment allocation. We conducted a literature review and meta-analysis to investigate the use of autologous anti-CD19 CAR T cell therapy in both pediatric and adult patients with R/R B-ALL, using several databases including MEDLINE, Cochrane Central, ScienceDirect, Web of Science, Journals@Ovid, Embase, and clinicaltrial.gov. A total of 38 reports were analyzed, which enrolled 2134 patients. Time-to-event endpoints were estimated using reconstructed patient survival data. The study explored key modulators of response, including costimulatory domains, disease status, age, and lymphodepletion. The median overall survival and event-free survival were 36.2 months [95% CI 28.9, NR] and 13.3 months [95% CI 12.2, 17], respectively. The overall response rate was 76% [95% CI 71, 81]. The use of 4-1BB costimulatory domain in the CAR construct, administration of low-dose cyclophosphamide lymphodepletion, and pretreatment morphologic remission were associated with better overall survival, with hazard ratios of 0.72, 0.56, and 0.66, respectively. Morphologic remission and 4-1BB domain were associated with better event-free survival, with hazard ratios of 0.66 and 0.72, respectively. These findings suggest that CAR T cell therapy may offer long-term benefits to patients with R/R B-ALL. However, further research is needed to optimize patient selection and better understand the impact of various factors on the outcome of CAR T cell therapy.