Merck's Single-Dose Monoclonal Antibody Clesrovimab Granted Priority Review in China for Prevention of RSV Lower Respiratory Tract Infection in Infants

▎WuXi AppTec Content Team Report

RSV is a contagious virus that causes widespread seasonal infections among infants and the elderly globally. Worldwide, RSV is the leading cause of hospitalization for healthy infants under one year of age, resulting in severe respiratory conditions such as bronchiolitis and pneumonia.

Clesrovimab is an investigational long-acting monoclonal antibody for passive immunization to prevent RSV.The product is designed to be administered in a single, uniform dose regardless of the infant’s birth weight, aiming to provide direct, rapid, and long-lasting protection for healthy preterm infants, full-term infants, and high-risk infants., helping them fend off mild, moderate, and severe RSV infections during their first RSV season.

The submission of Clesrovimab for marketing authorization in the United States is based on the results of the pivotal 2b/3 phase clinical trial CLEVER (MK-1654-004), a randomized, placebo-controlled trial that evaluatedSafety and Efficacy of a Single Dose of Clesrovimab in Healthy Premature and Full-Term Infants (From Birth to 1 Year) Entering Their First RSV Season; and the interim results of the ongoing Phase 3 clinical trial SMART (MK-1654-007), which is evaluating clesrovimab against approved long-acting RSV antibody therapies inHigh-Risk Infants and Childrenfor safety and efficacy in China. The data from these trials were presented at the Infectious Diseases Week (IDWeek) conference held in October 2024.Publish。

Among them, the CLEVER study recruited 3,632 participants who were randomly assigned in a 2:1 ratio.Receive a single fixed dose of clesrovimab (105 mg) or placebo intramuscularly on Day 1. The primary efficacy endpoint of the trial was to evaluate the effect of clesrovimab in reducing the incidence of medically attended lower respiratory tract infections (MALRI) associated with RSV within 150 days (5 months) after vaccination, compared to placebo. The trial met its primary efficacy endpoint,The effectiveness of clesrovimab reaches 60.4%.. In addition,Clesrovimab reduced RSV-related hospitalization rates and RSV-related lower respiratory tract infection (LRI) hospitalization rates by 84% and over 90%, respectively, within five months.。

According to the official website of the Chinese Drug Clinical Trial Registration and Information Disclosure Platform,The Chinese part of the CLEVER study has also been completed, with 449 subjects enrolled in China.。

This innovative antibody drug is proposed to be included in the priority review in China, meaning that the product is expected to reach patients more quickly.

References:

[1] Center for Drug Evaluation (CDE) of the National Medical Products Administration (NMPA) of China.Retrieved Mar 28，2025, From https://www.cde.org.cn/main/xxgk/listpage/4b5255eb0a84820cef4ca3e8b6bbe20c

[2] Merck Announces FDA Acceptance of Biologics License Application for Clesrovimab, an Investigational Long-Acting Monoclonal Antibody Designed to Protect Infants from RSV Disease During their First RSV Season. Retrieved December 17, 2024, from https://www.merck.com/news/merck-announces-fda-acceptance-of-biologics-license-application-for-clesrovimab-an-investigational-long-acting-monoclonal-antibody-designed-to-protect-infants-from-rsv-disease-during-their-first-rsv/