Merck's Anfu Chang® (Clesrovimab) Launches Commercially in China

en.Wedoany.com Reported - On September 9, according to MSD China, Merck's long-acting monoclonal antibody for the prevention of respiratory syncytial virus (RSV), Anfu Chang (Clesrovimab Injection), has officially launched commercially in China for neonates and infants entering or born during their first RSV season to prevent RSV-associated lower respiratory tract infection. The product is administered as a single fixed dose, requiring no weight-based dose adjustment for neonates and infants. Clesrovimab had previously been approved by China's National Medical Products Administration (NMPA), and this commercial launch marks a new milestone in its transition from regulatory approval to market availability in China.

In June, the NMPA approved the marketing of Clesrovimab Injection, submitted by Merck Sharp & Dohme B.V., through a priority review and approval procedure, with the trade name Anfu Chang and the approved indication being the prevention of lower respiratory tract infection in neonates and infants during their first RSV season. According to the product labeling published by MSD China, the recommended dose for the first RSV season is 105 mg, administered as a single intramuscular injection of 0.7 mL, with no need to select different doses based on infant weight before administration. For infants undergoing cardiac surgery with cardiopulmonary bypass during the RSV season, the labeling recommends an additional 105 mg dose as soon as the infant is stable after surgery.

The core clinical development program for Clesrovimab includes the CLEVER study. ClinicalTrials.gov registration information shows that CLEVER is a randomized, double-blind, placebo-controlled Phase IIb/III study that enrolled 3,632 healthy preterm and full-term infants, who received a single 105 mg dose of Clesrovimab or placebo. The study primarily evaluated the incidence of RSV-associated lower respiratory tract infection requiring medical intervention and safety within 150 days after administration. Study results published by Merck showed that, compared with placebo, Clesrovimab reduced the incidence of RSV-associated lower respiratory tract infection requiring medical intervention by 60.5% and the rate of RSV-associated hospitalization by 84.3% during the 150-day observation period.

Merck is also advancing an indication expansion for Clesrovimab in children at high risk for severe RSV disease. Its SMART Phase III study, which enrolled 1,003 high-risk infants and young children, has been completed; in August 2026, the U.S. FDA accepted the related supplemental Biologics License Application, proposing to expand the intended use to children under 2 years of age who remain at high risk for severe disease during their second RSV season. Merck also disclosed that Clesrovimab has now been approved in more than 40 countries and regions, including China, the United States, Canada, the European Union, and Japan, for use in infants during their first RSV season.