Merck MRK announced that the FDA has accepted the biologics license application (BLA) for its investigational prophylactic long-acting monoclonal antibody, clesrovimab (MK-1654), designed to protect infants from respiratory syncytial virus (RSV) disease entering their first RSV season.

With the FDA accepting the BLA for review, a decision from the regulatory body is expected on June 10, 2025.

Clesrovimab is likely to be available by July 2025 in the United States.

If approved, clesrovimab can help address the burden of RSV disease in time for the 2025-26 RSV season.

Year to date, shares of Merck have declined 8.3% against the industry’s rise of 5.3%.

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More on MRK's BLA for Clesrovimab

The above BLA for clesrovimab was based on data from the pivotal phase IIb/III CLEVER (MK-1654-004) study and interim data from the ongoing phase III SMART (MK-1654-007) study.

The placebo-controlled CLEVER study evaluated a single dose of clesrovimab administered to healthy preterm and full-term infants (birth to one year of age), while the SMART study investigated the safety and efficacy of clesrovimab versus Synagis (palivizumab) in infants and children who are at increased risk for severe RSV disease.

Data from the CLEVER study showed that treatment with a single dose of clesrovimab significantly reduced the incidence of RSV disease and hospitalization in healthy preterm and full-term infants.

Other RSV Antibodies/Vaccines Available in the Market

AstraZeneca AZN and Sanofi’s SNY RSV antibody Beyfortus (nirsevimab) was approved in the United States in July 2023 for newborns and infants.

AstraZeneca records a 50% share of gross profits on sales of Beyfortus in major markets outside the United States, which it receives from Sanofi.

AZN also records Beyfortus product sales from products supplied to partner SNY.

In the first nine months of 2024, Beyfortus recorded sales worth €845 million. Beyfortus sales benefited from early deliveries in the United States and launch in countries like Canada, France, Germany, Spain, Portugal, Belgium and Ireland.

Pfizer’s PFE RSV vaccine, Abrysvo, was launched to help protect older adults as well as infants through maternal immunization in the United States as well as in the EU in 2023.

PFE’s Abrysvo recorded sales of $557 million in the first nine months of 2024.

PFE’s Abrysvo was approved for the prevention of lower respiratory tract disease (LRTD) caused by RSV in patients aged 18-59 years who are at increased risk of the disease by the FDA in October 2024.

GSK’s Arexvy is currently approved in the United States, Europe, Japan and several other countries for adults aged 60 and above for the prevention of LRTD caused by RSV. This was the first RSV vaccine for older adults to be approved anywhere in the world.

In the first nine months of 2024, Arexvy generated £432 million in sales.

Arexvy was approved for high-risk adults aged 50-59 years in the United States and the European Union in June and August 2024, respectively.

MRK's Zacks Rank

Merck currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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