Clinical separation of cGvHD and GvL and better GvHD-free/relapse-free survival (GRFS) after unrelated cord blood transplantation for AML

Few studies have presented a comparison of myeloablative cord blood transplantation (CBT) and HLA-identical sibling hematopoietic cell transplantation (HCT) for AML in a disease-specific analysis, and the evaluation of GvHD-free and relapse-free survival (GRFS) in AML patients after unrelated CBT has not been reported. A total of 162 consecutive AML patients receiving intensified myeloablative unrelated CBT (n =107) or allogeneic PBSC transplantation (allo-PBSCT) or bone marrow transplantation (BMT) from an HLA-identical sibling donor (n=55) were investigated. Neutrophil or platelet engraftment was slower in the CBT cohort compared with that in the allo-PBSCT/BMT cohort. The incidence of grade II-IV or grade III-IV acute GvHD (aGvHD) and transplant-related mortality (TRM) were not significantly different in the two cohorts. Compared with the allo-PBSCT/BMT cohort, the CBT cohort had a significantly lower rate of chronic GvHD (cGvHD) (13.7% vs 28.3%; P=0.047) or extensive cGvHD (9.9% vs 24.1%; hazard ratio (HR) = 2.06, P= 0.039). The incidence of relapse at 5 years in the CBT cohort was significantly lower than that in the allo-PBSCT/BMT cohort (15.3% vs 36.1%; HR=4.62, P=0.009). The probabilities of overall survival and leukemia-free survival were similar between the two cohorts. The adjusted 5-year probability of GRFS was higher after CBT than that after allo-PBSCT/BMT (55.4% vs 39.2%; HR = 1.63, P= 0.042). The present study suggests that, for AML patients, intensified myeloablative unrelated CBT is associated with less cGvHD and a lower risk of relapse. In addition, these patients do not experience excessive TRM or severe aGvHD that translates into better GRFS compared with those patients who undergo HLA-identical sibling allo-PBSCT/BMT; this observation may reflect the clinical separation between cGvHD and GvL within our CBT protocol.