Cytomegalovirus induces strong antileukemic effect in acute myeloid leukemia patients following sibling HSCT without ATG-containing regimen

A considerable number of studies have demonstrated that cytomegalovirus (CMV) reactivation after allogeneic hematopoietic stem cell transplantation (Allo-HSCT) could enforce graft-versus leukemia (GVL) effect in acute myeloid leukemia (AML) patients. However, the use of antithymocyte globulin (ATG) as part of graft-versus-host disease (GVHD) prophylaxis may dampen this beneficial effect of CMV replication. In this context, we retrospectively analyzed the effect of CMV reactivation on relapse, survival and prognosis in a total of 227 AML patients who received a myeloablative (MA) conditioning regimen at a single research center between January 2010 and April 2013. Of these 227 patients, 110 cases received non-ATG-containing regimens and 117 cases received ATG-containing regimens. CMV reactivation occurred in 45 patients (41%) among non-ATG regimen group and 73 patients (62%) among ATG regimen group (P = 0.001). At a median time to follow-up of 27.5 months, a lower risk of cumulative relapse incidence associated with CMV reactivation was observed in non-ATG group in multivariate analyses (OR 0.28, 95% CI 0.10-0.79; P = 0.016). However, CMV reactivation after transplantation did not significantly decrease the cumulative incidence of relapse in our ATG group (OR 0.28, 95% CI 0.10-0.79; P = 0.016). Collectively, our results demonstrate that in AML patients following sibling HSCT, the CMV-induced beneficial effect on relapse occurs only in the MA regimens containing no ATG, although ATG promotes CMV reactivation.