Merck's investigational RSV monoclonal antibody clesrovimab demonstrates positive results

Merck's investigational RSV monoclonal antibody clesrovimab demonstrates positive results | Image Credit: © Guru - © Guru - stock.adobe.com.

Positive, topline safety and efficacy data has been reported for clesrovimab (MK-1654; Merck), an investigational prophylactic monoclonal antibody created to protect infants from respiratory syncytial virus (RSV) disease, according to a press release from Merck. The positive data is from the phase 2b/3 MK-1654-004 (NCT04767373) clinical trial.¹

The trial to evaluate safety and efficacy of clesrovimab in healthy preterm and full-term infants is a double-blind, randomized, placebo-controlled study with an estimated (actual) 3632 participant enrollment number, according to study details posted to ClinicalTrials.gov. Clesrovimab is being developed currently to "provide rapid, durable protection through [infants] first RSV season with a single, fixed-dose administration," stated Merck in the press release.^1,2

Patients received either a single dose of clesrovimab or placebo, with the primary endpoints as the incidence of participants with RSV-associated medically attended lower respiratory infection (MALRI) from day 1 (post dose) to day 150, compared to placebo and safety. Percentage of participants with any injection-related adverse events (AEs), AEs of special interest, solicited systemic AEs, or serious AEs were safety measures assessed in the trial. Merck announced clesrovimab met all primary safety and efficacy endpoints, and that additional detailed findings will be presented at an upcoming scientific congress.¹

"Merck plans to file these data with global regulatory authorities," the company also stated in the press release.¹

From a global perspective, RSV remains the leading cause of hospitalizations for healthy infants under 1 year of age. The respiratory disease can lead to conditions such as bronchiolitis and pneumonia, which cause an estimated 101,000 deaths per year worldwide among children younger than 5 years of age.

According to a study published in April 2024, RSV hospitalizations quadrupled in 2022 among children aged 2 to 5 years, who were almost 5-times more likely to be hospitalized because of RSV that year compared to anytime between 2015 and 2019. Click here for more information about the study and additional data.³

Providers would welcome the addition of another way to prevent RSV disease in this vulnerable population, just as they welcomed the FDA approved nirsevimab (Beyfortus; Sanofi and AstraZeneca) in July 2023, and Pfizer's maternal RSV vaccine (Abrysvo) in August 2023.^4,5

[Those approvals] were fantastic because it really put other tools in our toolbox that we could use to prevent severe complications [we saw] with RSV, especially in the younger infants under 6 months of age," said Contemporary Pediatrics editor in chief Tina Tan, MD, FAAP, FIDSA, FPIDS, in a previous interview.³

References:

1. Merck announces topline results from phase 2b/3 trial of clesrovimab (MK-1654), an investigational respiratory syncytial virus preventative monoclonal antibody for infants. Merck. Press release. July 23, 2024. Accessed July 24, 2024. https://www.merck.com/news/merck-announces-topline-results-from-phase-2b-3-trial-of-clesrovimab-mk-1654-an-investigational-respiratory-syncytial-virus-preventative-monoclonal-antibody-for-infants/
2. Efficacy and safety of clesrovimab (mk-1654) in infants (MK-1654-004). ClinicalTrials.gov. Updated July 16, 2024. Accessed July 24, 2024. https://clinicaltrials.gov/study/NCT04767373
3. Kenzmann, K. RSV hospitalizations quadrupled among young children after COVID-19. Contemporary Pediatrics. April 18, 2024. Accessed July 24, 2024. https://www.contemporarypediatrics.com/view/rsv-hospitalizations-quadrupled-young-children-covid-19
4. Fitch, J. Nirsevimab-alip FDA approved to prevent RSV in neonates, infants. Contemporary Pediatrics. July 17, 2023. Accessed July 24, 2024. Contemporary Pediatrics. https://www.contemporarypediatrics.com/view/nirsevimab-alip-fda-approved-to-prevent-rsv-in-neonates-infants
5. Fitch, J. What Pfizer's maternal RSV vaccine means for the infant population. Contemporary Pediatrics. August 22, 2023. Accessed July 24, 2024. https://www.contemporarypediatrics.com/view/what-pfizer-s-maternal-rsv-vaccine-means-for-infant-population