[Impact of HLA compatibility on the outcome of allogeneic hematopoietic stem cell transplantation for chronic myeloid leukemia].

Objective: To analyze the influence of HLA compatibility on the outcome of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with chronic myeloid leukemia (CML).

Methods: This retrospective study involved 121 CML patients including 90 in chronic phase, 8 in accelerated phase and 23 with blast crisis. Of these patients, 85 received related and 36 had unrelated donor allo-HSCT. The conditioning regimens included total body irradiation with cyclophosphamide in 37 patients, and modified BUCY protocol in 84 patients. Cyclosporine A (CsA) and methotrexate (MTX) were used for graft-versus-host disease (GVHD) prophylaxis in patients undergoing HLA-matched sibling donor transplants. CsA, MTX, antihuman thymocyte globulin and mycophenolate were used in all the patients undergoing HLA-mismatched related donor and unrelated donor transplants. The prognostic factors of CML were evaluated using Cox regression and the cumulative overall survival and the disease-free survival were estimated using Kaplan and Meier survival analysis model.

Results: The incidence of II-IV acute GVHD was 26.1% in HLA-matched and 53.3% in HLA-mismatched cases (P=0.006), with a 5-year cumulative incidence of chronic GVHD of 47.4% and 49.6%, respectively (P=0.947). The 5-year cumulative incidences of disease relapse was 16.7% in the total patients, with a 5-year cumulative overall survival (OS) of 70.5% and disease-free survival (DFS) of 63.4%. The 5-year OS was 78.2% in HLA-matched cases, as compared with 47.6% in HLA-mismatched cases. Multivariate analysis with Cox regression model identified HLA mismatch, II-IV acute GVHD, and advanced phase as the risk factors affecting the OS.

Conclusion: HLA mismatch can significantly increase the incidence of II-IV acute GVHD following allo-HSCT and decrease the long-term survival rate, which is not related to the donor source.