A prophylactic tyrosine kinase inhibitor strategy based on measurable residual disease pre-transplantation for Ph+ acute lymphoblastic leukemia undergoing allogeneic hematopoietic stem cell transplantation: A prospective multicenter cohort study

Relapse is the major cause of treatment failure in Philadelphia chromosome-positive (Ph⁺) acute lymphoblastic leukemia (ALL) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to evaluate the effect of a prophylactic tyrosine kinase inhibitor (TKI) strategy on relapse in this population. Patients were assigned to prophylactic or control groups based on measurable residual disease (MRD) pre-transplantation. The primary endpoint was the cumulative incidence of relapse. A total of 110 patients with Ph⁺ ALL undergoing allo-HSCT were enrolled in this prospective study. Thirty-eight patients with positive MRD pre-transplantation were included in the prophylactic group, and 72 with negative MRD pre-transplantation were included in the control group. The 4-year cumulative incidence of relapse was 25.3% (95% CI: 12.1%–41.0%) and 20.3% (11.6%–30.7%; HR = 1.272, 95% CI: 0.551–2.940, p = .549), and non-relapse mortality was 10.5% (3.3%–22.7%) and 9.7% (4.2%–17.9%; HR = 1.094, 95% CI: 0.320–3.738, p = .928) in the prophylactic and control groups. The 4-year overall survival was 71.8% (53.2%–84.1%) and 84.1% (72.9%–90.9%; HR = 1.746, 95% CI: 0.741–4.112, p = .196), and leukemia-free survival was 64.1% (45.8%–77.7%) and 70.0% (57.6%–79.4%; HR = 1.212, 95% CI: 0.607–2.421, p = .585) in the prophylactic and control groups. Our results suggest that prophylactic TKI post-HSCT in patients with positive MRD pre-transplantation can produce outcomes comparable to negative MRD pre-transplantation without TKI post-HSCT.