Idenix Falls After U.S. FDA Delays Hepatitis C Drug Trial

Idenix Pharmaceuticals Inc., a U.S. drugmaker that stopped development of two hepatitis C therapies this year, plunged the most in almost three years after regulators asked for more safety data on another experimental treatment.

Idenix dropped 31 percent to $3.55 at the close in New York, the biggest single-day decline since September 2010. Food and Drug Administration officials said they needed more safety information about IDX20963 for hepatitis C before allowing human clinical trials to begin, the Cambridge Massachusetts-based company said yesterday in a statement.

Idenix is among companies including AbbVie Inc. and Gilead Sciences Inc. seeking new medicines for the viral disease that attacks the liver and affects an estimated 170 million people worldwide. Analysts estimate the market for such new drugs is $20 billion. The request for more data is expected to delay the start of the clinical program for IDX20963, Idenix said.

“There is a lot more uncertainty right now in terms of when it’s going to Phase 1, if at all,” said Geoffrey Meacham, a JPMorgan Chase & Co. analyst who today lowered the rating on the company to neutral from overweight. “I think it will, but it could be a delay of three months or more,” he said in a telephone interview.

Idenix in February stopped development of two experimental hepatitis C therapies after a drug in the same class of compounds from Bristol-Myers Squibb Co. was linked to heart risks.

The company has declined 66 percent in the past 12 months.

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