Drug major Merck & Co., Inc. (MRK) announced late Wednesday that the U.S. Food and Drug Administration has issued a Complete Response Letter or CRL regarding its New Drug Application or NDA for gefapixant under development for the treatment of refractory chronic cough or RCC or unexplained chronic cough or UCC in adults.
Gefapixant is an investigational, non-narcotic, oral selective P2X3 receptor antagonist. In the CRL, the FDA concluded that Merck's application did not meet substantial evidence of effectiveness for treating RCC and UCC.
The CRL was not related to the safety of gefapixant. Merck said it is reviewing the FDA's feedback to determine next steps.
In adults with RCC, the cough persists despite appropriate treatment of underlying conditions such as asthma or gastroesophageal reflux disease. Further, UCC is a cough where the underlying cause cannot be identified despite a thorough evaluation.
Joerg Koglin, senior vice president, global clinical development, Merck Research Laboratories, said, "We thank our clinical trial participants and investigators for their important contributions that add to the body of knowledge related to chronic cough and help to raise awareness about the significant unmet medical need and the impact of RCC and UCC on patients. Acknowledging the absence of any approved treatments for refractory or unexplained chronic cough, we are disappointed in the FDA's response to our application for gefapixant."
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