Cytomegalovirus (CMV) infection is a common complication that surfaces in recipients after allogeneic hematopoietic cell transplantation (alloHCT) and may lead to overall detrimental effects on the transplant outcome.1,2 Antiviral prophylaxis (where antivirals are given to all transplant recipients) or preemptive therapies (where antivirals are prescribed only if CMV is detected) are used to counter the risk of CMV infection in alloHCT recipients.3 The success of preemptive therapy depends on early detection, since the early reactivation of CMV in transplant recipients is associated with significant morbidity and mortality.1,2 This leads to the consideration of antiviral prophylaxis, which can effectively prevent early CMV activation.1,2 The mainstay antiviral drugs like valganciclovir, foscarnet, and cidofovir are often associated with a high incidence of toxicity and adverse drug reactions in these patients, propelling the development of novel antivirals.1,2 Letermovir is a relatively novel antiviral drug that targets the deoxyribonucleic acid terminal transferase of CMV and inhibits its maturation.2,4 This medicine was approved by the United States Food and Drug Administration (FDA) in 2017 as a prophylactic treatment for alloHCT CMV-seropositive recipients, based on the efficacy results of a phase 3 randomized clinical trial.1,2 Letermovir is safe and efficacious with a favorable tolerability profile, but its clinical performance should be persistently monitored in the real-world setting.1,2,5 In the 48th Annual Meeting of the European Society for Blood and Marrow Transplantation (EBMT) held in March 2022, Raval et al. presented the results of a systematic review and meta-analysis of the real-world observational studies on the impact of letermovir as primary prophylaxis in adult alloHCT recipients in a clinical setting.6
