Idenix Shares Fall as J&J Buys Rival Hepatitis C Therapy

Idenix Pharmaceuticals Inc., a maker of experimental hepatitis C therapies, fell the most in almost four months after partner Johnson & Johnson bought a rival drugmaker’s treatment for the viral disease.

Idenix declined 16 percent to $3.99 at the close in New York. It was the stock’s biggest one-day slide since June, when U.S. regulators requested more safety data for one of its hepatitis C drugs. The Cambridge, Massachusetts-based company has fallen 18 percent so far this year.

Idenix, J&J, AbbVie Inc. and Gilead Sciences Inc. are among drugmakers vying to develop pills for hepatitis C, a disease that attacks the liver and affects an estimated 170 million people worldwide. The new oral treatments, which combine different drugs, are easier to use with fewer side effects than the current therapies. Analysts estimate the market for the new treatments may reach $20 billion a year.

J&J, the world’s largest seller of health-care products, bought rights to a compound from London-based GlaxoSmithKline Plc in a class of drugs called non-structural 5A protein inhibitors. That suggests J&J may be close to ending a partnership with Idenix on its hepatitis C therapies including the NS5a drug samatasvir, Brian Abrahams, an analyst with Wells Fargo & Co., said today in a note to clients.

The deal shows “Hep C battle lines being drawn,” Abrahams said. Idenix’s drug “will need a new partner.”

J&J, based in New Brunswick, New Jersey, didn’t release terms of its deal with Glaxo in today’s statement announcing the purchase. Idenix in February ended development of two other medicines for hepatitis C.

Before it's here, it's on the Bloomberg Terminal.