Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced that the U.S. Food and Drug Administration (FDA) has issued a Complete Response Letter (CRL) regarding Merck’s New Drug Application (NDA) for gefapixant, the investigational, non-narcotic, orally administered selective P2X3 receptor antagonist, under development for the treatment of refractory chronic cough (RCC) or unexplained chronic cough (UCC) in adults. In March 2021, Merck announced that the FDA accepted the company’s NDA for gefapixant. In the CRL, the FDA requested additional information related to measurement of efficacy. The CRL was not related to the safety of gefapixant. Merck is reviewing the letter and will meet with the agency to discuss next steps.

“We remain committed to advancing gefapixant for patients with refractory or unexplained chronic cough and will work with the FDA to address the agency’s feedback,” said Dr. Roy Baynes, senior vice president and head of global clinical development, chief medical officer, Merck Research Laboratories. “We believe there is a significant unmet need to help patients manage their chronic cough, as there are no available treatment options indicated in the U.S. specifically for this condition.”

Last week, the Japan Ministry of Health, Labor and Welfare (MHLW) approved LYFNUA^® (gefapixant) Tablets 45 mg for adults with refractory or unexplained chronic cough. In Japan, LYFNUA is the planned trademark for gefapixant; the trademark for gefapixant in other countries has not been approved. Outside of Japan, gefapixant is an investigational treatment and is still under review by other regulatory bodies.

About Chronic Cough

The prevalence of chronic cough (a cough lasting more than 8 weeks) is estimated to be approximately 5% of adults in the U.S. In a subset of these cases, patients either do not respond to treatment of underlying conditions (such as asthma or gastroesophageal reflux), known as refractory chronic cough (RCC), or they have no identifiable underlying condition despite a thorough evaluation, known as unexplained chronic cough (UCC). There are currently no approved therapies for the treatment of RCC or UCC in the U.S.

About Merck

For over 130 years, Merck, known as MSD outside the United States and Canada, has been inventing for life, bringing forward medicines and vaccines for many of the world’s most challenging diseases in pursuit of our mission to save and improve lives. We demonstrate our commitment to patients and population health by increasing access to health care through far-reaching policies, programs and partnerships. Today, Merck continues to be at the forefront of research to prevent and treat diseases that threaten people and animals – including cancer, infectious diseases such as HIV and Ebola, and emerging animal diseases – as we aspire to be the premier research-intensive biopharmaceutical company in the world. For more information, visit www.merck.com and connect with us on Twitter, Facebook, Instagram, YouTube and LinkedIn.

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