The efficacy of short-course blinatumomab immunotherapy as a bridge-to-HSCT in ph-negative B-cell acute lymphoblastic leukemia

Abstract Introduction Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) provides a potential cure for patients with Ph-negative B-cell acute lymphoblastic leukemia (Ph-B-ALL), the post-transplant relapse remains a therapeutic challenge. Earlier and deeper minimal residual disease (MRD) remission has the potential to improve this outcome. Full-course blinatumomab has been demonstrated to significantly improve overall survival (OS) in MRD-negative patients undergoing allo-HSCT. Here, we reported the effect of short-course blinatumomab administered before allo-HSCT on transplant outcomes in MRD-negative patients assessed by multiparameter flow cytometry (MFC). Methods In this retrospective analysis, twenty-three Ph-B-ALL patients in hematologic complete remission received blinatumomab 15 µg/m2per day for up to 14 days (blinatumomab group) and forty-seven patients received conventional chemotherapy (chemotherapy group). Then all these seventy Ph-B-ALL patients subsequently underwent allo-HSCT. The primary end point was 18-month RFS (relapse-free survival) and OS rate. Results All enrolled patients achieved MRD-negative status (<10⁻⁴ sensitivity) as assessed by MFC before allo-HSCT. The Kaplan-Meier estimate of RFS at 18 months was 62.8% (95% CI: 65.2%-89.8%) and the corresponding OS was 74.4% (95% CI:51.2%-77.1%). In landmark analyses, patients in the blinatumomab cohort had higher 18-month rates of RFS (78.5% vs 55%; p = .033), GVHD-free relapse-free survival (GRFS) (71.3% vs 45.5%; p = .043), and OS (95.6% vs 69.7%; p = .077) compared with the chemotherapy cohort. Additionally, although blinatumomab did not improve non-relapse mortality, it resulted in a significant reduction in relapse (p = .03). This immunotherapy did not affect the incidence of grade 2-4 acute graft-versus-host disease (GVHD) (8.76% vs. 13.1%, p = .15) significantly reduced the incidence of chronic GVHD (10.14% vs. 35.8%, p = .05) compared with the chemotherapy cohort.Conclusion Compared to the chemotherapy group, bridging transplantation with short-course blinatumomab provided superior survival benefits, significantly reduced relapse rates, and decreased the incidence of post-transplant chronic GVHD.