FOSTER CITY, Calif. (AP) -- Shares of Gilead Sciences are sinking in pre-market trading. The drugmaker says a promising hepatitis C treatment it recently acquired may have to be used with other drugs in patients with the disease.
The Foster City, Calif., company said Friday that some patients in a small part of a mid-stage study relapsed within a month of completing the treatment. The potential drug is labeled GS-7977, and Gilead is studying it in hepatitis C patients with genotype 1, the most prevalent subset of the disease in the Western world and the hardest to treat.
Hepatitis C can lead to life-threatening liver damage.
Gilead acquired the potential treatment in an $11 billion deal for Pharmasset Inc.
Shares of Gilead are down $9.97, or 18.2 percent, to $44.84 in pre-market trading.