Prognostic factors influencing clinical outcome of allogeneic hematopoietic stem cell transplantation following imatinib-based therapy in BCR-ABL-positive ALL.

We investigated prognostic factors for the clinical outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) following imatinib-based therapy. Among 100 adult patients who were prospectively enrolled in the JALSG Ph+ALL202 study, 97 patients obtained complete remission (CR) by imatinib-combined chemotherapy, among whom 60 underwent allo-HSCT in their first CR. The probabilities of overall survival (OS) and disease-free survival (DFS) at 3 years after HSCT were 64% (95% CI, 49-76) and 58% (95% CI, 43-70), respectively. Prognostic factor analysis revealed that the major BCR-ABL transcript was the only unfavorable predictor for OS and DFS after HSCT by both univariate (HR, 3.67 (95% CI 1.49-9.08); P=0.005 and HR, 6.25 (95% CI, 1.88-20.8); P=0.003, respectively) and multivariate analyses (HR, 3.20 (95% CI, 1.21-8.50); P=0.019 and HR, 6.92 (95% CI, 2.09-22.9); P=0.002, respectively). Minimal residual disease status at the time of HSCT had a significant influence on relapse rate (P=0.015). Further study of the BCR-ABL subtype for the clinical impact on outcome of allo-HSCT in Ph+ALL is warranted.