Merck Provides Update on FDA Advisory Committee Meeting Evaluating Gefapixant


November 17, 2023 5:31 pm ET

RAHWAY, N.J., Nov. 17, 2023 – Merck (NYSE: MRK), known as MSD outside of the United States and Canada, today announced the outcome of the U.S. Food and Drug Administration (FDA) Pulmonary-Allergy Drugs Advisory Committee (PADAC) meeting, which discussed the New Drug Application (NDA) for gefapixant, an investigational, non-narcotic, oral selective P2X3 receptor antagonist, developed for the treatment of refractory chronic cough (RCC) or unexplained chronic cough (UCC) in adults. The Advisory Committee voted 12 to 1 that the evidence does not demonstrate that gefapixant provides a clinically meaningful benefit to adults with refractory or unexplained chronic cough.

Chronic cough is defined as a cough lasting longer than eight weeks. In adults with RCC, the cough persists despite appropriate treatment of underlying conditions such as asthma or gastroesophageal reflux disease, and UCC is a cough where the underlying cause cannot be identified despite a thorough evaluation. Currently, there are no approved therapies to treat refractory or unexplained chronic cough.

The PADAC provides the FDA with independent, expert advice and recommendations on investigational medicines for use in the treatment of pulmonary disease and diseases with allergic and/or immunologic mechanisms. The FDA is not bound by the Advisory Committee’s guidance but takes its advice into consideration. The FDA has set a Prescription Drug User Fee Act (PDUFA), or target action, date of Dec. 27, 2023.

“We disagree with the Committee’s assessment based on the strong, comprehensive gefapixant data showing a meaningful clinical benefit for adults with refractory or unexplained chronic cough,” said Dr. Joerg Koglin, senior vice president, global clinical development, Merck Research Laboratories. “Merck believes in the value gefapixant can provide to adults living with this condition and today’s discussion underscored the clear need for new treatments.”

About gefapixant
Gefapixant is an investigational, non-narcotic, orally administered, selective P2X3 receptor antagonist, for the potential treatment of refractory or unexplained chronic cough. P2X3 receptors are one of the receptor types found on sensory nerve fibers, predominantly C fibers, in the airway lining. Chemical stimuli, including adenosine triphosphate (ATP), can be released from airway lining cells due to airway inflammation, irritation and mechanical stress/injury. Binding of extracellular ATP to P2X3 receptors on C fibers in the airway can be sensed as a signal of potential damage, creating an action potential, which may initiate coughing. The inhibition of binding of extracellular ATP to P2X3 receptors is thought to reduce sensory nerve activation and, subsequently, cough. Gefapixant under the brand name LYFNUA, has been approved in Japan, Switzerland, and the European Union for treatment of adults with refractory or unexplained chronic cough.

About refractory and unexplained chronic cough
The prevalence of chronic cough (a cough lasting more than 8 weeks) is estimated to be approximately 5 to 10% of adults globally. In a subset of chronic cough cases, patients either do not respond to treatment of underlying conditions (such as asthma or gastroesophageal reflux), known as RCC, or they have no identifiable underlying condition despite a thorough evaluation, known as UCC. People living with RCC or UCC experience uncontrollable coughing bouts, which can last for months or years. Cough hypersensitivity is a common characteristic in patients with RCC or UCC and includes allotussia, a cough triggered by trivial or low-level stimuli not normally sufficient to cause cough, such as cold air, singing, talking, or fatigue and stress, and hypertussia, a cough that is triggered in response to cough-inducing stimuli, such as inhaled chemical irritants.

About Merck
At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit and connect with us on Twitter, Instagram, YouTube and LinkedIn.

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