This study evaluated the efficacy and safety of tisagenlecleucel, an anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in children and young adults with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). The primary endpoint was the overall remission rate within 3 months. A total of 75 patients received tisagenlecleucel, and the overall remission rate was 81%, with all patients achieving negative minimal residual disease. The 6-month relapse-free survival rate was 80%, and the 12-month overall survival rate was 76%. The median duration of remission was not reached, and tisagenlecleucel persistence was observed for up to 20 months. Grade 3 or 4 adverse events occurred in 73% of patients, with cytokine release syndrome being the most common. Neurologic events occurred in 40% of patients but were managed with supportive care. The study demonstrated that tisagenlecleucel provided durable remission and long-term persistence in patients with relapsed or refractory B-cell ALL, with transient high-grade toxic effects.This study evaluated the efficacy and safety of tisagenlecleucel, an anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in children and young adults with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL). The primary endpoint was the overall remission rate within 3 months. A total of 75 patients received tisagenlecleucel, and the overall remission rate was 81%, with all patients achieving negative minimal residual disease. The 6-month relapse-free survival rate was 80%, and the 12-month overall survival rate was 76%. The median duration of remission was not reached, and tisagenlecleucel persistence was observed for up to 20 months. Grade 3 or 4 adverse events occurred in 73% of patients, with cytokine release syndrome being the most common. Neurologic events occurred in 40% of patients but were managed with supportive care. The study demonstrated that tisagenlecleucel provided durable remission and long-term persistence in patients with relapsed or refractory B-cell ALL, with transient high-grade toxic effects.