Letermovir and Maribavir for the Treatment and Prevention of Cytomegalovirus Infection in Solid Organ and Stem Cell Transplant Recipients.

Until recently, available drugs for cytomegalovirus (CMV) prevention and treatment in transplant patients included (val)ganciclovir, foscarnet, and cidofovir. Use of these drugs is limited by toxicity and the development of resistance. The 2017 approval of letermovir for prevention of CMV after stem cell transplant marked the first approval of an anti-CMV agent since 2003. The role of letermovir in treatment of established CMV infection or disease remains largely unstudied, although early reports suggest that a low barrier to resistance will likely limit efficacy as primary therapy for patients with refractory or resistant disease. The investigational agent maribavir has shown promise as preemptive treatment; in patients with refractory or resistant disease the emergence of resistance while on treatment has been observed and ongoing studies will define efficacy in this population. Both agents have unique mechanisms of action limiting cross resistance, and neither exhibit myelotoxicity or nephrotoxicity.