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News|Articles|July 26, 2024

Investigational RSV Monoclonal Antibody Meets all Trial Endpoints

Merck’s antibody, clesrovimab (MK-1654), is designed to protect infants against medically attended lower respiratory infections (MALRI) caused by RSV.

This week, Merck announced positive topline results from its phase 2b/3 clinical trial (MK-1654-004) evaluating clesrovimab (MK-1654), the company’s investigational prophylactic monoclonal antibody designed to protect infants from respiratory syncytial virus (RSV) disease. In the trial, clesrovimab met its primary safety and efficacy endpoints, including reducing medically attended lower respiratory infections (MALRI) caused by RSV through Day 150.1

“We are encouraged by these findings and look forward to working with regulators to provide a new option to help address the impact of RSV on infants and their families" said Paula Annunziato, MD, senior vice president, infectious diseases and vaccines, Global Clinical Development, Merck Research Laboratories.1

Participants were randomized to receive either a single dose of clesrovimab or placebo. The primary endpoints include the incidence of participants with RSV-associated medically attended lower respiratory infection from Day 1 (post dose) to Day 150 as compared to placebo and safety. Safety measures assessed included the percentage of participants with any injection-related adverse events (AEs), AEs of special interest (AESIs) solicited systemic AEs, or serious adverse events (SAEs).1

What You Need to Know

Merck’s investigational monoclonal antibody, clesrovimab (MK-1654), successfully met all primary safety and efficacy endpoints in its phase 2b/3 trial. The drug showed effectiveness in reducing medically attended lower respiratory infections (MALRI) caused by RSV in infants.

RSV poses a significant health risk to infants, with 58,000-80,000 hospitalizations annually in the U.S. The infection can cause severe respiratory issues, making a preventive treatment like clesrovimab particularly valuable.

Following these promising results, Merck plans to present detailed findings at a scientific congress and will submit the data to global regulatory authorities for approval.

Clesrovimab is an investigational extended half-life monoclonal antibody (mAb) developed as a passive immunization for the prevention of RSV-associated medically attended lower respiratory infection (MALRI). Clesrovimab is being studied in infants (pre-term and full-term) to provide rapid, durable protection through their first RSV season with a single, fixed-dose administration.1

Scope of RSV in Pediatric Population

Currently, the burden of RSV in infants is significant. According to the Centers for Disease Control and Prevention (CDC), 58,000-80,000 children younger than 5 years are hospitalized due to RSV infection annually. “RSV is highly contagious and can cause inflammation in the airways of infants leading to difficulty breathing. As a widespread illness globally, RSV is the leading cause of hospitalization for healthy infants,” Annunziato said.1,2

Next Steps

With favorable data, the company plans to move forward with studies. Merck said detailed findings of the study will be presented at an upcoming scientific congress and Merck plans to file these data with global regulatory authorities.

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 26, 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.RSV in Infants and Young Children. CDC. June 5, 2024. Accessed July 26, 2024. https://www.cdc.gov/rsv/infants-young-children/index.html

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