Comparing the impact of blinatumomab therapy versus standard chemotherapy on the progression of relapsed/refractory pediatric B-ALL: a two-center retrospective cohort study

BACKGROUND: Despite advances in risk-adapted chemotherapy and allogeneic hematopoietic stem cell transplantation (allo-HSCT), relapse remains the leading cause of treatment failure and mortality in pediatric acute lymphoblastic leukemia (ALL). Achieving measurable residual disease (MRD)-negative status prior to allo-HSCT is strongly associated with improved outcomes. This study aimed to compare the effectiveness of blinatumomab versus conventional re-induction chemotherapy in relapsed/refractory pediatric B cell acute lymphoblastic leukemia (B-ALL) patients. METHOD: This retrospective, non-randomized cohort study included pediatric patients (1-18 years) diagnosed with relapsed/refractory CD19⁺ B-ALL. Patients received either conventional re-induction chemotherapy followed by consolidation according to institutional protocols or blinatumomab administered as a continuous intravenous infusion in 28-day cycles. Treatment allocation was based on physician decision and drug availability. Primary endpoints included complete remission (CR) and MRD negativity after one treatment cycle. Secondary endpoints included eligibility for allo-HSCT, relapse-free survival, overall survival, and adverse events. RESULTS: A total of 52 patients were analyzed (blinatumomab, n = 30; chemotherapy, n = 22). MRD negativity after one cycle was significantly higher in the blinatumomab group compared with chemotherapy (83.4% vs. 18.2%, P < 0.001). A greater proportion of patients in the blinatumomab group proceeded to allo-HSCT (68.2% vs. 40%, P = 0.041). Overall survival was significantly improved with blinatumomab (77.3% vs. 30%, P < 0.001). Mortality was primarily associated with FAB type L3 following the first treatment cycle. CONCLUSIONS: In this retrospective cohort of pediatric patients with relapsed/refractory B-ALL, blinatumomab was associated with significantly higher MRD negativity rates, improved transplant eligibility, and superior survival compared with conventional chemotherapy. These findings support the role of blinatumomab as an effective therapeutic option in this high-risk population.