Merck, with GSK in its rearview, suffers second FDA rejection of cough drug gefapixant
The FDA has put a lump of coal in Merck & Co.’s stocking. Following the recommendation of its advisory committee, the agency has issued a second complete response letter for the chronic cough drug gefapixant, giving GSK a shot at coming from behind to capture the untapped market.
Merck received its first FDA rejection for gefapixant, a P2X3 receptor antagonist designed to treat chronic cough, at the start of last year. The Big Pharma recounted coughs in two pivotal trials to try to address the FDA’s worries, only for the agency to publish an advisory committee briefing document that reflected doubts about whether the molecule has clinically meaningful effects.
Those doubts informed a 12-1 advisory committee vote against gefapixant—and now the FDA’s decision to again reject the molecule. The FDA gave Merck the news one week ahead of the decision deadline.
Merck said the FDA concluded that the filing fell short of the requirement for substantial evidence of effectiveness in the two targeted indications, refractory chronic cough and unexplained chronic cough in adults. The drug developer, which voiced disappointment at the FDA’s decision given the unmet need, is reviewing the latest feedback from the agency before deciding on the next steps.
At this stage, it is unclear what the next steps may entail. Merck won approval earlier this year in the European Union, where it persuaded regulators that a “modest effect” on cough and “manageable” side effects supported authorization, but has now failed twice to deploy its existing data to bring the drug to the U.S. market.
The rejections will have provided information on how to design studies that deliver the data requested by the FDA, but running another trial will mean investing more time and money in gefapixant. Delays are eating into the headstart that Merck had over GSK, which lists September 2024 and July 2025 as the primary completion dates for phase 3 trials of a rival asset it acquired from Bellus Health.