Feasibility of blinatumomab in newly diagnosed pediatric B-cell acute lymphoblastic leukemia patients requiring modification of standard chemotherapy.

PURPOSE: Newly diagnosed pediatric B-cell acute lymphoblastic leukemia (B-ALL) patients who require modification of standard chemotherapy because of severe treatment-related toxicities or inadequate early response represent an understudied population with limited therapeutic evidence. We evaluated the efficacy and safety of blinatumomab in this real-world clinical setting. METHODS: We conducted a retrospective, single-center analysis of 15 pediatric patients with newly diagnosed CD19-positive B-ALL treated with blinatumomab between May 2022 and December 2024 because of severe chemotherapy-related toxicities, inadequate early response, or individualized treatment modification. Clinical response, minimal residual disease (MRD) status, hematologic parameters, and adverse events (AEs) were evaluated before and after therapy. RESULTS: Most patients (86.7%) presented with high tumor burden at diagnosis. Notably, eleven patients received a 14-day course, two patients received a 16-day course, and two patients completed the standard 28-day treatment cycle. Following one cycle, blinatumomab induced MRD-negative remission in all six patients with persistent disease before treatment (four with MRD positivity and two with >5% residual bone marrow blasts). The remaining nine patients had already achieved MRD-negative remission after chemotherapy but received blinatumomab because further chemotherapy could not be continued owing to severe treatment-related toxicities; all maintained MRD-negative status during subsequent blinatumomab therapy. Significant improvements were observed in white blood cell counts, hemoglobin, and platelet levels compared with baseline (all P < 0.05). The most frequent AEs were fever (66.7%), neutropenia (40.0%), elevated transaminases (26.7%), and neurological symptoms (20.0%). All AEs were manageable and reversible; no treatment-related deaths occurred. CONCLUSIONS: Blinatumomab demonstrated encouraging efficacy and a favorable safety profile in newly diagnosed pediatric B-ALL patients requiring modification of standard chemotherapy. It achieved MRD clearance in patients with residual disease while maintaining MRD-negative remission in those unable to continue conventional chemotherapy because of severe toxicities, and was associated with rapid hematologic recovery. An abbreviated 14-day regimen also appeared feasible and well tolerated in this real-world cohort.