Merck's Gefapixant Faces FDA Scrutiny Again After Prior NDA Rejection for Chronic Cough Treatment

　　【Pharmaceutical Network Product Information】Chronic Refractory Cough (CRC) is a long-term cough condition that persists for eight weeks or longer. Even after receiving treatment, the cough symptoms remain unrelieved, significantly impacting the patient's quality of life. This disease presents a significant market opportunity for treatment. According to a report by Bellus, there are approximately 2.6 million patients with recurrent/refractory chronic cough in the United States, representing a potential market worth billions of dollars.
 

P2X3 Receptor Antagonists Seen as a New Direction for Treating Adult Refractory CoughP2X3 receptor antagonists are regarded as one of the new directions for treating adult refractory cough. Their mechanism of action is to reduce patients' cough symptoms by inhibiting the activity of P2X3 receptors. Currently, many companies worldwide, including giants like Eli Lilly, MSD, and Bayer, are developing this type of drug.
 

Among them, MSD's Lyfnua (gefapixant) was approved in Japan in January 2022. This drug is an oral, selective P2X3 receptor antagonist used to treat adult patients with refractory chronic cough (RCC) or unexplained chronic cough (UCC). Regarding dosage, the Lyfnua 45mg tablet is taken twice daily.
 

It is reported that Gefapixant is an oral, selective P2X3 receptor antagonist, under development for the treatment of refractory or unexplained chronic cough. It is one of the leading investigational drugs in its class and has the potential to capture a multi-billion dollar market in the treatment of chronic cough.
 

Merck & Co., Inc. is known as MSD outside the United States and Canada. In January 2022, Merck & Co., Inc. announced that the U.S. FDA had rejected the New Drug Application (NDA) for its novel cough medication gefapixant (MK-7264). The FDA also requested additional data information.
 

However, MSD clearly has not abandoned the application for this new drug to be marketed in the U.S., but judging from the progress, the road to market for this drug has not been smooth. According to reports, staff at the U.S. health regulatory agency said on Wednesday that the data for MSD's chronic cough drug may not be sufficient to demonstrate the actual efficacy of this treatment.
 

At the same time, an expert advisory panel of the U.S. FDA will meet on Friday to discuss the efficacy of Merck's drug gefapixant. An evaluation of the data submitted by Merck by the staff shows that patients taking the drug have a slight reduction in cough frequency and side effects such as reduced taste. Compared with the placebo, the higher dose of the drug can significantly reduce the average number of coughs per hour within 24 hours.
 

To date, there are no approved drugs for the treatment of chronic cough in the United States.
 

Globally, in the development field of P2X3 receptor antagonists, Camlipixant (BLU-5937), which is being developed by Bellus Health, is also progressing rapidly and has now entered Phase 3 clinical trials. Public data indicates that the preliminary research on Camlipixant has shown excellent performance in treating chronic refractory cough, particularly in its selectivity for P2X3 receptors and P2X2/3 receptors. This suggests that Camlipixant may reduce the incidence of taste disorder side effects more effectively compared to MSD's Gefapixant.
 

In addition to multinational companies, domestic pharmaceutical enterprises are also actively deploying in the field of P2X3 receptor antagonist research and development, such as R&L Development, Hansoh Pharma, Takeda Pharmaceutical, and Hangzhou Vitan, with multiple products currently in Phase 2 or Phase 1 clinical trials.
 

In China, there are numerous patients with respiratory diseases, and chronic cough is a particularly common condition that troubles many people. Its prevalence increases with age and is associated with poorer health conditions. Currently, the treatment needs faced by patients in China are also very substantial. With the initiation of clinical trials for related treatment products by Chinese pharmaceutical companies, there is hope that new treatment options will be brought to a wide range of patients in the future.
 

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