The promising efficacy of a risk-based letermovir use strategy in CMV-positive allogeneic hematopoietic cell recipients.

Letermovir is the first approved drug for cytomegalovirus (CMV) infection prophylaxis in adult patients who are CMV positive undergoing allogeneic hematopoietic cell transplantation (allo-HCT). Because CMV infection risk varies from patient to patient, we evaluated whether a risk-based strategy could be effective. In this single-center study, all consecutive adult patients who were CMV positive and underwent allo-HCT between 2015 and 2021 were included. During period 1 (2015-2017), letermovir was not used, whereas during period 2 (2018-2021), letermovir was used in patients at high risk but not in patients at low risk, except in those receiving corticosteroids. In patients at high risk, the incidence of clinically significant CMV infection (csCMVi) in period 2 was lower than that in period 1 (P < .001) by week 14 (10.5% vs 51.6%) and week 24 (16.9% vs 52.7%). In patients at low risk, although only 28.6% of patients received letermovir in period 2, csCMVi incidence was also significantly lower (P = .003) by week 14 (7.9% vs 29.0%) and week 24 (11.2% vs 33.3%). Among patients at low risk who did not receive letermovir (n = 45), 23 patients (51.1%) experienced transient positive CMV DNA without csCMVi, whereas 17 patients (37.8%) experienced negative results. In both risk groups, the 2 periods were comparable for CMV disease, overall survival, progression-free survival, relapse, and nonrelapse mortality. We concluded that a risk-based strategy for letermovir use is an effective strategy which maintains the high efficacy of letermovir in patients at high risk but allows some patients at low risk to not use letermovir.