[The mechanisms and salvage treatment strategies underlying positive relapse following CD19 CAR-T cell therapy in B-acute lymphoblastic leukemia].

Approximately 50% of patients suffering from relapsed/refractory B-acute lymphoblastic leukemia (R/R B-ALL), experience relapse within one year, with around 60% of these relapses being antigen-positive, despite the transformative impact of chimeric antigen receptor (CAR) T cell therapy. The mechanisms underlying relapse are primarily associated with tumor heterogeneity, CAR-T cell dysfunction, subopimal in vivo expansion and persistence, and an inhibitory immune microenvironment. This review aims to investigate salvage strategies designed to enhance outcomes for patients undergoing relapse or disease progression following the CAR-T cell therapy. These strategies include a second CAR-T cell infusion that targets either the same antigen or an alternative target, the administration of immune checkpoint inhibitors, and the utilization of novel targeted therapies including monoclonal antibodies, antibody-conjugated drugs and small molecule compounds aimed at mitigating CD19-positive relapse or overcoming CAR-T cell resistance. Nevertheless, achieving improved long-term survival for these patients continues be challenging.