Effects of conditioning intensity in allogeneic stem cell transplantation for Philadelphia chromosome‑positive acute lymphoblastic leukemia.

We retrospectively analyzed the outcomes of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) who underwent first allogeneic stem cell transplantation (allo-SCT) at complete remission (CR) with myeloablative conditioning (MAC, n = 31) or reduced-intensity conditioning (RIC, n = 15) between 2001 and 2012. All the patients had received tyrosine kinase inhibitor (TKI)-based chemotherapy prior to allo-SCT. Overall survival (OS) rates (57 vs 63%, p = 0.53), leukemia-free survival rates (50 vs 65%, p = 0.29), and non-relapse mortality rates (39 vs 35%, p = 0.62) at 2 years were similar between the MAC and RIC groups. The minimal residual disease (MRD) status evaluated by sensitive polymerase chain reaction prior to allo-SCT did not influence the OS rate (77 vs 54%, p = 0.28) and leukemia-free survival rate (69 vs 51%, p = 0.48), irrespective of the conditioning intensity. Our data suggest that the RIC regimen may represent a sufficient intensity of therapeutic pre-transplant conditioning for patients with Ph+ALL who have maintained a hematological CR with TKI-combined chemotherapy.