Federal regulators have approved a promising new drug to treat flu symptoms. Clinical trials are expected to start within a few weeks.
The medication currently known as GP1681 is being developed by San Francisco–based Gemmus Pharma. The company announced on Monday its investigational new drug application was accepted by the Food and Drug Administration, allowing for the start of Phase 1 clinical trials in healthy adults in either the second or third quarter of 2015, according to company CEO William Guilford in an e-mail response
Guilford said GP1681 represents a new approach to treating influenza that would make it effective against any strain of the virus including those that have become drug-resistant to a flu vaccine or current therapies such as neuraminidase inhibitors, like Tamiflu, and amantadines.
"Existing therapies that target the virus and are sensitive to the development of drug resistance are effective for only the first 48 hours after the start of symptoms and do not directly reduce flu symptoms," he said. "GP1681 was designed to address these issues by targeting the patient's response to the virus and directly reducing flu symptoms. The approach is effective in animal models of influenza."
Amantadines are a class of antiviral medications that are not recommended for treating flu in the U.S. because they have been shown to have high levels of antiviral resistance, according to the Centers for Disease Control and Prevention.
This past flu season was particularly severe, due in large part to a reduced effectiveness of this year's vaccine. The dominant strain of the virus this year was H3N2, but that strain mutated over the course of the season, which made the vaccine only 19% effective against infection.
From Oct. 1, 2014, through Feb. 21, the rate of hospitalizations from flu-related illness was 51 per 100,000 people; according to a March CDC report. Antiviral medications were effective against this season's strains, which showed little resistance against neuraminidase inhibitor medications.
Questions, however, have arisen over the ability of medications like Tamiflu to reduce the severity of flu symptoms. A review released in April 2014 by the Cochrane Collaboration concluded Tamiflu shortened flu symptoms by half a day, and found no evidence that the treatment helped reduce hospitalizations from the illness.
But a subseqeunt analysis published in January in the Lancet found Tamiflu cut flu symptoms by a day, and helped reduce the risk of developing more severe complications in some patients.
Guilford expects the market for GP1681 to be the same, if not greater, than for Tamiflu because of its potential to treat those who have had flu symptoms longer than the 48-hour window during which Tamiflu and similar medications are seen as most effective.