Merck’s New CMV Drug Approved in China Targets Nearly 40000 HSCT Patients

On June 23, 2025, Merck announced that its novel non-nucleoside cytomegalovirus (CMV) inhibitor, Letermovir, in both tablet and injectable forms, has been approved by the National Medical Products Administration (NMPA) for use in children aged 6 months and above, weighing ≥6kg.

The newly approved indication covers the prevention of CMV infection and disease in allogeneic hematopoietic stem cell transplant (HSCT) recipients who are CMV-seropositive (R+), including adults and children. According to Merck, Letermovir is the first and only CMV prevention therapy in China available for both pediatric and adult HSCT patients.

CMV, a prevalent herpes virus, poses a severe threat to transplant recipients, significantly increasing transplant-related mortality rates. In China, CMV infection is widespread, with 60%-80% of infants testing positive for antibodies. Children, who lack fully developed immune systems, face an increased risk of CMV reactivation after transplantation.

Data shows that in 2022 and 2023, there were 39,918 HSCT recipients in China, of which 9,860 were children—accounting for 1 in every 4 transplant patients. The approval of Letermovir addresses a critical unmet need in CMV prevention for this vulnerable group.

Previously approved CMV inhibitors in China include Roche’s ganciclovir and valganciclovir, while domestic companies such as Zhejiang Asia-Pacific Pharmaceutical and Shanghai Pharma have also entered the market with generic versions. However, Letermovir offers a novel mechanism of action, making it a game-changing option for CMV prevention in HSCT patients, particularly children.