FDA review heralds first-in-class status for Gilead's hep C drug sofosbuvir

Friday's FDA panel review of Gilead's hep C drug sofosbuvir is shaping up as a marketing event. In an internal staff review released this morning, regulators said that the hep C drug combined with ribavirin would offer the first all-oral treatment for two key genotypes of hepatitis C patients, offering faster cures and an improved safety profile over anything currently on the market. And it presents a promising alternative for the large number of patients who can't tolerate the harsh impact of interferon injections.

Gilead's ($GILD) sofosbuvir appears headed for a quick if not early approval from the FDA, which would set it firmly on a path to a megablockbuster market, with a wide variety of analysts estimating peak annual sales at $5 billion-plus. And that would more than justify the $11 billion Gilead paid to get the treatment in the Pharmasset buyout.

The FDA concluded that "the currently available data support a favorable benefit-risk assessment for the use of sofosbuvir as part of a combination regimen for the treatment of chronic hepatitis C. In the HCV GT 2 and 3 populations, the sofosbuvir and ribavirin combination regimen provides the first all-oral, interferon-free treatment, as well as a shorter treatment duration and improved safety profile compared to the current standard of care interferon-based regimen. In addition, SOF+RBV provides a therapeutic option for patients who are ineligible, intolerant or unwilling to take interferon-based regimens, thus addressing an unmet need in this patient population."

In the HCV GT 1 and 4 populations, sofosbuvir in combination with pegylated interferon and ribavirin provides increased efficacy and shorter treatment duration compared with currently approved regimens. The shorter 12 week duration translates into a better tolerated side effect profile with observed treatment discontinuations due to AEs of less than 2%. The available data are believed to be insufficient to make definite dosing recommendations for patients with GT 5 or 6."

No major safety issues were founded related to the therapy, according to the FDA.

Sofosbuvir is widely expected to quickly topple the leaders in the hep C market, Vertex's ($VRTX) Incivek and Victrelis from Merck ($MRK). Both of those companies have been hurrying along substitute programs, but they're well behind the likes of Gilead, AbbVie ($ABBV) and Bristol-Myers Squibb ($BMY), which are all focused on developing cocktail therapies that will extend across the various genotype groups, where response times and cure rates can vary.

Gilead's own company review of the therapy--documents which typically provide only the most positive aspects of a drug profile--add that this is a drug that can be taken once a day without food, often without most other meds and generally without a dose adjustment. All those aspects help distinguish the therapy from what's on the market today.

- here's the FDA review (PDF)
- and the company review (PDF)

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