Real-world experience with letermovir in primary prophylaxis of cytomegalovirus in adult patients after hematopoietic cell transplantation: summary of reported data

Abstract

Introduction: Letermovir (LMV) is a new antiviral agent approved in 2017 for prophylaxis to prevent cytomegalovirus (CMV) reactivation in CMV-seropositive allogeneic hematopoietic cell transplant recipients. Numerous reports on real-world experiences with LMV have been presented at international hematology and hematopoietic cell transplantation meetings. The objective of this study was to summarize data reported 2019–2020 on primary prophylaxis with LMV in adult patients. Methods: We analyzed 19 studies published or presented in 2019 and 2020, including two studies presented twice. Results: An overall 817 patients received primary prophylaxis with LMV. In 12 studies with a control group, the rate of breakthrough infection was 99/577 (17.2%) vs. 874/1,525 (57.3%), odds ratio (OR) =6.5 [95% confidence interval (CI) =5.1–8.2), p <0.0001]. In seven studies without a control group, the rate was 17/240 (7.1%). Overall breakthrough infection occurred in 116/817 (14.2%) patients on LMV primary prophylaxis vs. 874/1,525 (57.3%) without prophylaxis, OR =8.1 (95% CI =6.5–10.1), p <0.0001. Conclusions: LMV when used for primary prophylaxis challenges the standard of care for CMV reactivation based on preemptive therapy. Presented real-world data shows a significant improvement in reducing the risk of any CMV viremia and clinically significant CMV infection in all reported studies performed so far. LMV is a drug that breaks the paradigm of preventive therapy by moving it from pre-emptive treatment to prophylaxis.