A phase 3 clinical trial compared blinatumomab, a bispecific T-cell engager antibody, with standard chemotherapy in adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). The study enrolled 405 patients, with 376 receiving treatment. Blinatumomab significantly improved overall survival compared to chemotherapy, with a median survival of 7.7 months versus 4.0 months. The hazard ratio for death was 0.71 (95% CI, 0.55 to 0.93; P = 0.01). Blinatumomab also showed higher remission rates, with 34% complete remission with full hematologic recovery versus 16% in the chemotherapy group. Event-free survival was also better with blinatumomab, with 6-month estimates of 31% versus 12%. The median duration of remission was longer with blinatumomab (7.3 months vs. 4.6 months). Adverse events of grade 3 or higher were reported in 87% of blinatumomab patients and 92% of chemotherapy patients. Blinatumomab was associated with higher rates of serious adverse events, including neurologic events and cytokine release syndrome. Despite these risks, blinatumomab showed significant survival benefits and was associated with improved health-related quality of life. The trial was stopped early due to the survival benefit observed. Blinatumomab resulted in significantly higher rates of hematologic remission and longer survival than chemotherapy. The study highlights the potential of blinatumomab as a more effective treatment for relapsed or refractory ALL in adults.A phase 3 clinical trial compared blinatumomab, a bispecific T-cell engager antibody, with standard chemotherapy in adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). The study enrolled 405 patients, with 376 receiving treatment. Blinatumomab significantly improved overall survival compared to chemotherapy, with a median survival of 7.7 months versus 4.0 months. The hazard ratio for death was 0.71 (95% CI, 0.55 to 0.93; P = 0.01). Blinatumomab also showed higher remission rates, with 34% complete remission with full hematologic recovery versus 16% in the chemotherapy group. Event-free survival was also better with blinatumomab, with 6-month estimates of 31% versus 12%. The median duration of remission was longer with blinatumomab (7.3 months vs. 4.6 months). Adverse events of grade 3 or higher were reported in 87% of blinatumomab patients and 92% of chemotherapy patients. Blinatumomab was associated with higher rates of serious adverse events, including neurologic events and cytokine release syndrome. Despite these risks, blinatumomab showed significant survival benefits and was associated with improved health-related quality of life. The trial was stopped early due to the survival benefit observed. Blinatumomab resulted in significantly higher rates of hematologic remission and longer survival than chemotherapy. The study highlights the potential of blinatumomab as a more effective treatment for relapsed or refractory ALL in adults.