UPDATE: Idenix Says FDA Partial Hold On Hepatitis C Drug Lifted

Biopharmaceutical company Idenix Pharmaceuticals Inc. (IDIX) said the U.S. Food and Drug Administration's partial hold on its drug IDX184 has been lifted and a Phase 2B study evaluating the drug can continue, allowing the company to expand its trial.

Idenix, which focuses on researching drugs to treat human viral diseases, is developing IDX184, its lead hepatitis C drug. The stock jumped last month after Idenix reported positive interim data from a IDX184 trial and said it was advancing its hepatitis C drug development pipeline.

After the FDA reviewed interim safety and antiviral activity results of an IDX184 trial, it removed the partial hold and allowed continued enrollment in the study, the company said. Chief Executive Ron Renaud said the change allows the company to expand its study in evaluating the drug.

But despite the seemingly good news, shares came under pressure Friday. They were off 9% at $12 after Gilead Sciences Inc. (GILD) released positive data on its experimental hepatitis C drug that analysts warned could outperform Idenix's competing drug candidate.

"I think Gilead's drug is further ahead in development and clearly much better," said Brian Skorney, a Brean Murray Carret & Co. analyst, referring to its superior rate in making the liver-attacking virus undetectable.

Gilead last month completed its purchase of Pharmasset Inc. for more than $11 billion, in a deal expected to accelerate its hepatitis C drug pipeline. It said late Thursday that its GS-7977 drug--which it acquired in the deal--along with the older drug ribavirin, made hepatitis C undetectable after four weeks of treatment in 100% of patients. Its shares are up 8.4% at $53.46.

Idenix has been viewed as an acquisition target but could appear less attractive with a weaker hepatitis C drug. In interim results, its IDX184 drug, when adding in older drugs ribavirin and interferon, made the virus undetectable after four weeks in only 73% of patients, far less than GS-7977's results.

Gilead said it plans to gain first approval from the U.S. Food and Drug Administration on GS-7977 with ribavirin in the first half of 2014. It said there are over 12 million hepatitis C-infected individuals in commercial markets.

In November, Idenix said its third-quarter loss narrowed on reduced research and development costs, as well as lower general and administrative expenses, despite lower revenue.

-By Ben Fox Rubin, Dow Jones Newswires; 212-416-3108; ben.rubin@dowjones.com

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