US FDA staff flags concerns about Merck's chronic cough drug

On Wednesday(Nov 15), the U.S. health regulator's staff expressed concerns that the available data on Merck's chronic cough drug may be insufficient to establish its meaningful benefits, as indicated by documents released before an upcoming meeting of independent experts. Merck's shares experienced a slight decline in afternoon trade. These concerns arose subsequent to the company submitting additional efficacy data to the U.S. Food and Drug Administration (FDA), which had rejected the drug in January of the previous year. A panel of expert advisers to the FDA is scheduled to convene on Friday to deliberate on the efficacy of Merck's drug, gefapixant.

The staff's evaluation of the data from Merck revealed a modest decrease in cough frequency and noted side effects, such as a loss of taste, in patients who received the drug. Analyst Mara Goldstein from Mizuho expressed low expectations for the drug candidate in terms of efficacy and side effects, suggesting that an unfavorable outcome would not be surprising. Currently, there are no approved therapies for chronic cough in the United States, a condition estimated to affect approximately 10% of the global adult population. Roughly half of these patients lack an identifiable cause for their cough despite diagnostic tests.

Gefapixant operates by inhibiting receptors that stimulate nerves and trigger the urge to cough. The drug underwent evaluation in two late-stage trials, demonstrating a statistically significant reduction in the average number of coughs per hour over a 24-hour period compared to a placebo when administered at a higher dose. While the European Union and Japan have granted approval for Merck's drug for the condition, marketed under the brand name Lyfnua, the outlook for its success in the U.S. remains uncertain.