Letermovir for cytomegalovirus infection in allogeneic hematopoietic stem-cell transplantation: tips and notes for effective use in clinical practice.

LET inhibits CMV replication by binding to components of the DNA terminase complex. A phase 3 trial in allo-HSCT recipients showed a reduced incidence of clinically significant CMV infection in the LET group. In 2017, this agent was first approved for CMV prophylaxis in adult CMV-seropositive allo-HSCT recipients in the United States, and is now used worldwide. While LET has an excellent toxicity profile, there are issues to be aware of, such as interactions with other drug classes (e.g. immunosuppressants and antifungals) and reactivation of CMV infection following LET cessation. While LET is the current standard of care for CMV prophylaxis, there are no established protocols for preemptive treatment of asymptomatic CMV viremia or for treatment of developed CMV disease. Further research is needed to maximize the benefits of LET, including the discovery of biomarkers.