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.