Allogeneic stem cell transplantation for patients with chronic myeloid leukemia: Risk stratified approach with a long-term follow-up

The use of allogeneic stem cell transplantation (SCT) for chronic myeloid leukemia (CML) was almost abandoned in recent years for very effective targeted therapy with tyrosine kinase inhibitors (TKIs). However, approximately one third of patients still need another treatment including SCT. 38 consecutive CML patients were treated (most in preimatinib era) with allogeneic SCT, using partial T cell depletion (TCD) and preemptive donor lymphocyte infusion (DLI), without post-transplant graft-versus-host disease (GvHD) prophylaxis. Conditioning included busulfan, cyclophosphamide, antithymocytic globulin, and fludarabine followed by donor stem cell transfusion. With a median follow up of 90.5 months (1-134), 32 patients are alive. 97% engrafted. 5-year leukemia free survival (LFS) and overall survival (OS) were 78.95% and 84.2%, respectively. All patients are in major molecular remission and 78% in complete molecular remission. Transplant-related mortality (TRM) was 13%. Twenty-four patients received DLI for residual disease. Acute GvHD, mostly Grades I-II, occurred in 18% of patients post-transplant and in 24% of patients receiving DLI. In conclusion, the risk-adapted approach using only partial TCD and preemptive escalated dose of DLI precluded the need for immunosuppressive medications and reduced the risk of significant GvHD without compromising engraftment and long-term disease control.