US FDA Staff Expresses Concerns Over Merck’s Chronic Cough Drug Efficacy

Ahead of an upcoming meeting of independent experts, the U.S. health regulator’s staff has raised doubts about the adequacy of data supporting Merck’s chronic cough drug’s meaningful benefits, according to documents released on Wednesday. Merck’s shares dropped nearly 1 percent to $101.2 in afternoon trade following the news.

This concern emerged after Merck submitted additional efficacy data for the drug, which the U.S. Food and Drug Administration (FDA) had previously rejected in January of the previous year. A panel of expert advisers to the FDA is scheduled to meet on Friday to assess the efficacy of Merck’s drug, gefapixant.

The panel will specifically consider whether the data provided by Merck demonstrates that the reduction in cough frequency achieved with gefapixant is clinically significant for patients. Currently, there are no approved therapies for chronic cough in the United States. Globally, approximately 10 percent of the adult population is estimated to be affected by this condition, with about half of these individuals lacking an identifiable cause for their cough despite diagnostic tests.

Gefapixant functions by blocking receptors that stimulate nerves, thereby suppressing the urge to cough. The drug underwent evaluation in two late-stage trials, where a higher dose demonstrated a statistically significant reduction in the average number of coughs per hour over a 24-hour period compared to a placebo.

While the European Union and Japan have granted approval for Merck’s drug under the brand name Lyfnua, the FDA staff’s concerns highlight uncertainties about its efficacy in the U.S. market.