Merck's mAB Prevents RSV in Infants, Readies Regulatory Talks

Merck & Co. is vying to be the next major biopharmaceutical company to make strides in combating respiratory syncytial virus (RSV), following Moderna's recent approval for an RSV preventive treatment. Merck is banking on new data indicating that its monoclonal antibody, clesrovimab (also known as MK-1654), can significantly reduce RSV-related infections in infants.

Clesrovimab is specifically designed for preventive use in infants, including both healthy pre-term and full-term newborns. According to a release from Merck dated July 23, a phase 2b/3 clinical trial demonstrated that clesrovimab successfully achieved its primary goal: reducing the incidence of RSV-related infections over a 150-day period compared to a placebo. Additionally, the trial met crucial safety benchmarks, including the percentage of participants experiencing any injection-related adverse events (AEs), AEs of special interest, solicited systemic AEs, or serious AEs.

Despite these promising results, specific data on clesrovimab's performance in the clinical trial remains under wraps. Merck has indicated that detailed findings will be unveiled at a forthcoming scientific congress and submitted to global regulatory bodies.

Paula Annunziato, senior vice president of infectious diseases and vaccines at Merck Research Laboratories, expressed optimism about the trial results. She noted the company's eagerness to collaborate with regulators to offer a new option to mitigate the impact of RSV on infants and their families.

Historically, Merck had an RSV vaccine for adults in early-stage development. However, in 2020, the company decided to transfer this project to its long-time partner, Moderna, choosing to focus its efforts on developing clesrovimab. Moderna has since made significant progress in the RSV domain, securing FDA approval in May for an RSV vaccine for adults.

Currently, the RSV market is primarily dominated by GSK's Arexvy shot, which generated 182 million pounds (approximately $227 million) in the first quarter of the year. This is compared to Pfizer's competing product, Abrysvo, which brought in $145 million in the same period.

With the ongoing developments and pending detailed disclosures, Merck's clesrovimab could potentially become a key player in preventing RSV infections in infants, addressing a significant medical need and offering a new preventive option for families.