Short-course blinatumomab as a bridge-to-transplantation improves the survival of Ph-negative MRD-positive B-ALL

Post-transplant relapse remains the chief therapeutic challenge in Ph-negative B cell acute lymphoblastic leukemia (Ph^- B-ALL). This retrospective study evaluated whether short-course blinatumomab for measurable resident disease (MRD) eradication could improve transplant outcomes. We compared 23 patients receiving pre-transplant short-course blinatumomab (2-week) for MRD eradication with 46 chemotherapy-only controls. All achieved MRD-negative before allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Only two patients developed grade 2 cytokine release syndrome with blinatumomab. The neutrophil and platelet engraftment times were similar between the two groups. The blinatumomab cohort had a significantly lower 18-month cumulative incidence (CI) of relapse (p = 0.05) and chronic graft-versus-host disease (GVHD) (14.8% vs. 41.8%; p = 0.05), with comparable non-relapse mortality (NRM) (p = 0.98) and 180-day grade II-IV acute GVHD rates (p = 0.93). Consequently, this cohort showed superior 18-month relapse-free survival (RFS) (90.9% vs. 65.2%; HR 0.30, 95% CI 0.09-1.04; p = 0.04), improved 18-month overall survival (OS) (95.7% vs. 81.9%; HR 0.20, 95% CI 0.03-1.71), and a trend toward better GVHD-free and relapse-free survival (GRFS) (74.71% vs. 63.71%; HR 0.64, 95% CI 0.23-1.78). Multivariate analysis confirmed blinatumomab as an independent favorable factor for RFS. In conclusion, short-course blinatumomab as a bridge-to-transplantation could reduce the risk of relapse and improve survival for Ph^- B-ALL patients undergoing allo-PBSCT.