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FDA Accepts Biologics License Application for Clesrovimab to Protect Infants from RSV Infection
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Key Takeaways
- Clesrovimab is a long-acting monoclonal antibody designed for single-dose RSV protection in infants, regardless of weight.
- Clinical trials demonstrated clesrovimab's efficacy, reducing RSV-associated hospitalizations by over 84% and 90% for lower respiratory infections.
Clesrovimab would be the first and only single dose immunization indicated for infants regardless of weight, aimed to protect against their first RSV season.
The FDA has accepted a biologics license application for clesrovimab (MK-1654; Merck), a long-acting monoclonal antibody designed to protect infants from respiratory syncytial virus (RSV) infection during their first RSV season. If approved, clesrovimab would be the first and only single dose immunization indicated for infants regardless of weight.1
“Despite recent advances in RSV prevention, unmet needs remain for additional effective interventions to help protect infants and continue to help address the burden RSV places on families and the health care system. This regulatory milestone, along with promising results from our pivotal studies demonstrating efficacy in the prevention of RSV disease, marks important progress toward our goal of having clesrovimab available in time for the 2025-26 RSV season,” said Paula Annunziato, MD, senior vice president, infectious diseases and vaccines, Global Clinical Development, Merck Research Laboratories, in a news release.1
RSV can be dangerous among infants, particularly newborns less than 6 months old. According to the CDC, infants infected with RSV typically show symptoms that differ from adults, including irritability, decreased activity, eating or drinking less, and apnea. In most cases RSV presents as a mild, cold-like illness, although severe RSV can result in bronchiolitis or pneumonia. Data have demonstrated that 2 to 3 out of every 100 infants under 6 months are hospitalized with RSV annually. Additionally, an estimated 101,000 deaths occur globally each year in children under 5 years of age, highlighting the need for vaccination and protection among this patient population.1,2
As an investigational, extended half-life monoclonal antibody (mAb), clesrovimab was developed as a passive immunization to protect against RSV and is designed as a single dose injection, regardless of weight, according to study authors.1
The biologics license application was granted based on results from the randomized placebo-controlled phase 2b/3 CLEVER trial (MK-1654-004) that evaluated a single dose of clesrovimab in healthy preterm and full-term infants, along with interim results from an ongoing phase 3 SMART trial (MK-1654-007) that is evaluating the safety and efficacy of clesrovimab versus palivizumab (Synagis; Swedish Orphan Biovitrum AB) in infants and children at increased risk for severe RSV disease. Both studies aimed to to assess whether the immunization provides rapid and durable protection for infants through their first RSV season against mild, moderate, and severe RSV.1
Presented during IDWeek in October 2024, results from the phase 2b/3 trial demonstrated that clesrovimab reduced RSV-associated hospitalizations and RSV-associated lower respiratory infection hospitalizations by more than 84% and 90%, respectively, through 5 months. The study authors noted that the trial met both the secondary and tertiary end points.3
The FDA set a prescription drug user fee act date of June 10, 2025, for clesrovimab.1
“We look forward to working alongside the FDA on the review of clesrovimab, which, if approved, would be the first and only single dose immunization for infants regardless of weight designed to protect them for the duration of their first RSV season,” said Annunziato, in a news release.1
REFERENCES
1. 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. Merck. News release. December 17, 2024. Accessed December 19, 2024. 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/.
2. RSV in Infants and Young Children. CDC. News release. August 30, 2024. Accessed December 19, 2024. https://www.cdc.gov/rsv/infants-young-children/index.html#:~:text=Infants%20who%20get%20RSV%20almost,a%20fever%20with%20RSV%20infection.
3. Merck’s Clesrovimab (MK-1654), an Investigational Respiratory Syncytial Virus (RSV) Preventative Monoclonal Antibody, Significantly Reduced Incidence of RSV Disease and Hospitalization in Healthy Preterm and Full-term Infants. Merck. News release. October 17, 2024. Accessed December 19, 2024. https://www.merck.com/news/mercks-clesrovimab-mk-1654-an-investigational-respiratory-syncytial-virus-rsv-preventative-monoclonal-antibody-significantly-reduced-incidence-of-rsv-disease-and-hospitalization-in-heal/.
