Merck claims late-stage study success for RSV antibody

Dive Brief:

• An experimental Merck & Co. drug designed to protect infants from illness caused by respiratory syncytial virus succeeded in a late-stage trial, the company said Tuesday.
• In a statement, Merck said the therapy, an antibody called clesrovimab, met its main safety and efficacy objectives in a placebo-controlled trial involving more than 3,600 healthy or preterm infants. Those goals included the incidence of RSV-associated lower respiratory infections requiring medical attention over the course of five months, compared to placebo, as well as the percentage of patients experiencing certain types of adverse events.
• A spokesperson told BioPharma Dive in an email that clesrovimab met a key secondary measure by reducing the risk of hospitalization from RSV in the trial. But the company didn’t provide specifics on that result or the rest of the study findings, which will be presented at a future medical meeting. In the meantime, Merck plans to share the data with global health authorities.

Dive Insight:

Clesrovimab is one of several important experimental drugs for Merck, which is preparing for the expiry later this decade of key patents protecting its top-selling cancer medicine Keytruda.

One of those medicines, the pulmonary arterial hypertension drug Winrevair, has already reached market and has what analysts forecast as multibillion-dollar sales potential. Clesrovimab is another that Merck executives have highlighted, arguing it can stand out in a crowded, but lucrative, market for RSV therapies.

“We’re excited about it,” Merck’s research chief Dean Li said on an April earnings call. “We believe that this will be a distinguished monoclonal antibody.”

The treatment landscape for RSV, a common respiratory virus that can cause serious illness in infants and the elderly, has changed significantly. Since last year, three vaccines have become available. So too has an antibody drug called Beyfortus that, like Merck’s medicine, is meant to shield infants from RSV-related illness.

Sales of some of those products surged last fall, when infections of the seasonal virus tend to spike. GSK’s vaccine, Arexvy, tallied $1.5 billion in 2023. Sanofi and AstraZeneca struggled to meet the higher-than-anticipated demand for Beyfortus, which generated 547 million euros, or about $594 million, in 2023. It is expected to surpass $1 billion in sales this year.

Beyfortus has set a “high efficacy bar” for Merck’s drug to clear, Jefferies analyst Peter Welford wrote in a research note earlier this month. In two studies, Beyfortus lowered the risk of medically attended lower respiratory tract disease by 70% and 75%, respectively. The drug was also 83% effective in preventing hospitalizations from RSV-related illness in a third, larger trial, and associated with an 82% risk reduction in a study of real-world use that was published in The Lancet in April.

Merck executives have contended the virus is less likely to develop resistance to clesrovimab, and that its administration via a single fixed dose, rather than Beyfortus’ two injections, is an advantage. The drug was also associated with a similar reduction in the risk of lower respiratory tract infections in a small, early-stage trial.

But Welford noted that clesrovimab would have to also show an 80% to 90% reduction in hospitalizations to be considered “comparable” to Beyfortus.

Merck didn’t say specifically when it would disclose the study’s findings. 

Editor’s note: This story has been updated with a comment from a Merck spokesperson. 

This post has been syndicated from a third-party source. View the original article here.