“upfront use of blinatumomab in adolescents and adults with Philadelphia Chromosome–Negative B-cell acute lymphoblastic leukemia: A systematic review and proportional meta-analysis”

Abstract Background: Philadelphia chromosome–negative (Ph–) ALL is a genetically heterogeneous entity defined by recurrent cytogenetic and molecular aberrations that shape its clinical trajectory and prognosis. Historically poor outcomes in adults prompted significant changes in therapeutic approaches over the past decade, resulting in improved survival. Currently, blinatumomab is a bispecific T-cell engager targeting CD19 in leukemic cells and CD3 on T Lymphocytes. It has shown significant results in relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL). However, its role in the frontline treatment of Philadelphia chromosome–negative (Ph–) B-ALL, particularly in combination with chemotherapy, is continuously being explored. Objective: Our purpose is to evaluate the efficacy of blinatumomab-based frontline regimens in adolescents and adults with newly diagnosed Ph– B-ALL through a systematic review and meta-analysis of proportions. Methods: We systematically searched PubMed, Embase, and Cochrane from inception through May 2025. Eligible studies included adolescents or adults with a cut off age of 15 years old, with newly diagnosed Ph– B-ALL where blinatumomab was used in the induction phase, consolidation phase, or both. Primary outcomes were complete remission (CR), measurable residual disease (MRD) negativity, and 3-year overall survival (OS). Random-effects proportional meta-analyses were conducted using logit or Freeman–Tukey transformations. Risk of bias was assessed using RoB 2 for Randomized Controlled Trials and ROBINS-I for prospective trials. Subgroup analysis was performed, dividing subgroups by phase of Blinatumomab utilization; either induction, consolidation or both. To tackle heterogeneity in the MRD pooled results, we conducted a Meta-regression to evaluate the link between different treatment phases and sample sizes. Results: Thirteen studies (n = 878 patients) met the inclusion criteria. The pooled CR rate after induction-phase blinatumomab was 78% (95% CI: 71–85%; I² = 21.2%). The pooled MRD negativity rate was highest in the induction-only group, at 90% (95% CI: 83%–95%), with no significant heterogeneity (I² = 0%). The consolidation group showed a pooled MRD negativity rate of 88% (95% CI: 75%–96%), though heterogeneity was substantial (I² = 74.2%, p = 0.0087). For patients treated during both induction and consolidation, the pooled MRD negativity rate was 89% (95% CI: 82%–94%), also with no observed heterogeneity (I² = 0%). The overall pooled MRD negativity rate across all ten studies was 89% (95% CI: 84%–93%), using a random-effects model with Freeman–Tukey double arcsine transformation. A meta-analysis of four studies reporting 3-year overall survival (OS) following frontline blinatumomab-based therapy was performed, stratified by treatment phase. In the consolidation subgroup, the pooled 3-year OS was 83% (95% CI: 76%–88%), with no heterogeneity (I² = 0%, p = 0.4032). In contrast, for patients treated during both induction and consolidation, the pooled 3-year OS was 52% (95% CI: 22%–81%), with substantial heterogeneity (I² = 88.6%, p < 0.0001). Conclusions: Blinatumomab-based regimens in the frontline setting are associated with high MRD clearance and complete remission rates, particularly when used during induction or consolidation. However, the predominance of non-randomized studies, small sample sizes, and heterogeneity in MRD assessment limit definitive conclusions. Prospective randomized trials are needed to clarify the optimal integration of blinatumomab in frontline Ph– B-ALL therapy.