FDA said adding Gilead's sofosbuvir to the standard drug cocktail cured 90 percent of patients with the most common form of the virus in just 12 weeks.
The agency's reviewers state that the "shorter 12-week duration translates into a better tolerated side effect profile," adding that "no major safety issues associated with sofosbuvir have been identified to date."
Foster City, Calif.-based Gilead Sciences is one of a half-dozen drugmakers working to develop more effective treatments for hepatitis C, though many analysts predict the company's drug will eventually outperform its competitors. The FDA is expected to make a decision on the drug by Dec. 8.
Drugmakers see hepatitis treatments as a potentially lucrative market because the disease is expected to grow into a major public health problem as the baby boom generation ages. People born between 1945 and 1965 are five times more likely to have the virus than people of other age groups, and the Centers for Disease Control and Prevention is urging all baby boomers to get tested for the disease. Many Americans contracted the virus by sharing needles or having sex with an infected person in their youth.
For most of the last 20 years, the standard treatment for hepatitis C has involved a grueling one-year regimen of pills and injections that caused flu-like symptoms and cured less than half of patients. Then in 2011, the FDA approved two new drugs from Merck and Vertex Pharmaceuticals that raised the cure rate to about 65 and 75 percent, respectively, when combined with the older treatments.
Gilead's once-a-day pill appears to push the cure rate even higher.
In a company study of 327 patients with the most common form of the disease, 90 percent of participants had undetectable levels of the virus after 12 weeks of treatment. The form of the disease studied in the trial accounts for about 75 percent of hepatitis C cases in the U.S.
Gilead's drug was not as effective in treating two less common forms of the disease that account for about 25 percent of cases in the U.S. Among those patients, sofosbuvir cured about 67 percent of patients who had not previously taken other hepatitis C drugs.
But even for those patients, the FDA says Gilead's drug represents an important step forward.
The company's approach used only pill-based medications — sofosbuvir and another antiviral drug — while excluding interferon, the injectable medication that is the backbone of standard treatment, which can cause nausea, diarrhea and other unpleasant side effects.
For patients with the less common subtypes of the disease, Gilead's approach "provides the first all-oral, interferon-free treatment, as well as a shorter treatment duration and improved safety profile," according to the FDA's review.
Gilead is racing against other drugmakers to develop the first all-pill approach to treating the most common form of hepatitis C, long viewed as the holy grail of treatments by drugmakers. Similar efforts are underway from Abbott Laboratories, Bristol-Myers Squibb Co., Vertex Pharmaceuticals and others.
Pharmaceutical industry consulting firm Decision Resources estimates the market for hepatitis C drugs will grow to more than $23 billion by 2018. Sales of the drugs are expected to decline to $17.5 billion by 2021 as more patients are cured of the virus.
Shares of Gilead Sciences Inc. rose $1.01 to $69.10 in morning trading.