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Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic cell transplant (allo-HCT) has been associated with a 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. 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, .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 but suggest this protective effect of CMV reactivation on relapse is influenced by the conditioning regimen used with the transplant.

Pre-transplant remission status in patients with acute myeloid leukemia (AML) is one of the most important factors determining their outcomes after allogeneic hematopoietic cell transplantation (allo-HCT). Most patients are in complete remission with full hematologic recovery (CR) prior to undergoing allo-HCT. However, some patients achieve CR without recovery of platelet count (CRp) or a morphologic leukemia-free state (MLFS), defined as meeting all CR criteria without recovery of both neutrophil and platelet counts. Currently, there is a paucity of data regarding transplant outcomes in AML patients achieving MLFS after chemotherapy. To address this question, we evaluated transplant outcomes in 270 AML patients who received 6/6 HLA-matched sibling or 10/10 HLA-matched unrelated donor transplantation at a single institution between 2006 and 2013. Of our 270 patients, 206 were in complete remission (CR), 45 were in complete remission with incomplete platelet count recovery (CRp), and 19 were in MLFS prior to allo-HCT. Patients in CR, CRp, or MLFS had similar 3-year overall survival (49%, 46%, and 47%, respectively; P = 0.88) and 3-year event-free survival (45%, 36%, and 40%, respectively; P = 0.53). However, the cumulative incidence of non-relapse mortality (NRM) was significantly higher in patients in MLFS compared to those in CR (58% vs. 22%, P =0.0004), while the cumulative incidence of relapse in patients in MLFS was significantly lower compared to those in CR (11% vs. 36%, P = 0.03). Our results suggest that survival outcomes in AML patients are not influenced by degree of hematologic recovery prior to allo-HCT.