Impact of Cytomegalovirus Reactivation Following Allogeneic Hematopoietic Cell Transplantation on the Relapse of Acute Leukemia.

Background: Cytomegalovirus (CMV) reactivation following allogeneic hematopoietic cell transplantation (HCT) is a significant complication; however, its impact on relapse remains controversial.

Objectives: This study aimed to evaluate the clinical impact of CMV reactivation on relapse and survival after HCT in patients with acute leukemia.

Study Design: We conducted a retrospective analysis of 1258 patients diagnosed with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) who underwent their first HCT between 2000 and 2020.

Results: Our cohort included 871 patients with AML and 387 patients with ALL. Among all patients, 751 (61.6%) experienced CMV reactivation within one year post-HCT. CMV reactivation was associated with HCT from unrelated donors, anti-thymocyte globulin use, and the occurrence of acute graft-versus-host disease. Notably, CMV reactivation was associated with a lower risk of relapse (HR, 0.713; P = .001) and improved event-free survival (HR, 0.743; P = .001) in both AML and ALL patients. However, there was no significant difference in non-relapse mortality or overall survival according to CMV reactivation.

Conclusion: These results suggest that CMV reactivation may prevent post-HCT relapse and enhance event-free survival in AML and ALL patients. Therefore, a CMV prophylaxis strategy is warranted to establish a safe range of CMV reactivation titers that can yield beneficial effects.