Favorable outcome of unrelated cord blood transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph⁺ALL) is one of the highest-risk ALL groups. Whenever possible, patients with Ph⁺ALL should undergo allogeneic hematopoietic stem cell transplantation (HSCT) after induction of remission. Although unrelated cord blood transplantation (CBT) has become a common treatment in adult patients who lack a sibling donor, data on the efficacy of CBT for Ph⁺ALL are limited. We analyzed the clinical outcomes of 20 Ph⁺ALL patients who underwent CBT (n = 8) or unrelated bone marrow transplantation (BMT) (n = 12). The median age was 41 years (range, 17-55 years). All but one of the patients were treated with an imatinib-based regimen before HSCT, and 19 patients were in first complete remission (CR) and 1 patient was in second CR at the time of HSCT. Seventeen patients received a myeloablative conditioning regimen containing 12 Gy of total-body irradiation, and 3 received a reduced-intensity conditioning regimen. After a median of 26 months of follow-up, estimated 3-year overall and leukemia-free survival rates were 100% and 85%, respectively, after CBT, and 49% and 38%, respectively, after unrelated BMT. The CBT group had significantly better overall survival than the BMT group (P = .02). Although BCR-ABL transcript was detected in 4 of 8 CBT patients at transplantation, 7 patients remained in molecular CR. Our findings suggest that CBT may be a viable option as postinduction therapy for Ph⁺ALL in patients lacking a sibling donor.