Merck today announced promising safety and efficacy results from a phase 2/3 clinical trial of a monoclonal antibody it is developing to protect infants from respiratory syncytial virus (RSV) infection.
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If approved by federal regulators, clesrovimab (MK-1654-004) would be the second prophylactic monoclonal antibody injection against RSV for babies. In July 2023, the Food and Drug Administration (FDA) approved the first such RSV preventive for infants, nirsevimab-alip (Beyfortus), which is made by AstraZeneca. Unprecedented demand for Beyfortus last fall and winter led to some supply shortages.
In its announcement, Merck said clesrovimab met its primary safety and efficacy endpoints, including reductions in medically attended lower respiratory infections caused by RSV through day 150. The drug is given as a single fixed-dose injection.
Merck said it would release details about the study at an upcoming scientific meeting and will submit the data to global regulatory authorities.