(Reuters) -The U.S. health regulator's staff on Wednesday flagged concerns that data on Merck's chronic cough drug might not be enough to prove the treatment's meaningful benefit, documents released ahead of a meeting of independent experts showed.
Shares of the drugmaker were down nearly 1% at $101.2 in afternoon trade.
The concerns were raised after the company had submitted additional efficacy data to the U.S. Food and Drug Administration (FDA), which had declined to approve the drug in January last year.
A panel of expert advisers to the FDA is set to meet on Friday to discuss the efficacy of Merck's drug gefapixant.
The panel will deliberate whether the data provided by Merck establishes that a small reduction in cough frequency with the use of gefapixant is clinically meaningful to patients.
Currently, there are no approved therapies for chronic cough in the United States. The condition is estimated to affect about 10% of the adult population globally and roughly half of those patients do not have an identifiable cause for their cough despite diagnostic tests.
Gefapixant works by blocking receptors that stimulate the nerves and trigger the urge to cough.
The drug was evaluated across two late-stage trials where a higher dose showed statistically significant reduction in the average number of coughs per hour over a 24-hour period compared to placebo.
The European Union and Japan have approved Merck's drug for the condition and is sold under brand name Lyfnua.