Allogeneic stem cell transplantation with alemtuzumab-based conditioning for patients with advanced chronic myelogenous leukemia.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the treatment of choice for patients with chronic myelogenous leukemia (CML) who have failed or are intolerant to tyrosine kinase inhibitors (TKI). Myeloablative conditioning regimens have been associated with high treatment-related mortality (TRM) rate in such patients, and reduced-intensity conditioning (RIC) regimens are often preferred but have high rates of disease recurrence and graft-versus-host-disease (GVHD). We report our experience with nine CML patients (four chronic phase and five with accelerated phase or blast crisis) who failed TKI and underwent allo-HSCT using an alemtuzumab-based RIC regimen. The conditioning regimen was well tolerated and induced engraftment in all patients, and complete cytogenetic remission (CCyR) in eight of nine. Four patients, all with a history of accelerated phase or blast crisis, died. Four of the five remaining patients had a cytogenetic relapse a median of 10 months after transplantation. Donor lymphocyte infusion (DLI), TKI or both induced a CCyR in all cases. With a median follow-up of 47 months, five patients, including all those transplanted in first or second chronic phase, are alive and in remission. Allo-HSCT with an alemtuzumab-based conditioning regimen induces remission in patients with CML that have failed TKI therapy and has a low incidence of GVHD. Disease recurrence is frequent but responds to DLI. In some cases, restoration of susceptibility to TKI was observed. Outcomes may improve with the routine administration of post-transplant TKI.