Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic cell transplant (allo-HCT) has been associated with reduced risk of relapse in patients with acute myeloid leukemia (AML). However the influence of the conditioning regimen on this protective effect of CMV reactivation after allo-HCT is relatively unexplored. To address this, we evaluated the risk of relapse in 264 AML patients who received T cell replete, 6/6 HLA matched sibling or 10/10 HLA matched unrelated donor transplantation at a single institution between 2006 and 2011. Out of these 264 patients, 206 received myeloablative (MA) and 58 received reduced intensity conditioning (RIC) regimens. CMV reactivation was observed in 88 patients with MA conditioning and 37 patients with RIC. At a median follow up of 299 days, CMV reactivation was associated with significantly lower risk of relapse in patients who received MA conditioning both in univariate (P= .01) and multivariate analyses (hazard ratio of 0.5246, P= .006), however CMV reactivation did not significantly affect the risk of relapse in our RIC cohort. These results confirm the protective effect of CMV reactivation on relapse in AML patients after allo-HCT reported by previous studies, however they suggest that this protective effect of CMV reactivation on relapse is influenced by the conditioning regimen used with the transplant.

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