FDA puts clinical hold on valopicitabine over risk/benefit profile; Idenix plunges 34%

Swiss drug major Novartis and USA-based Idenix Pharmaceuticals have suspended trials of their co-developed hepatitis C drug, valopicitabine (MN283), after discussions with the US Food and Drug Administration highlighted an unfavorable risk/benefit profile in the clinical data on the novel HCV RNA polymerase inhibitor. On the day of the news, July 13, shares in Idenix plunged 34% to $3.80 in midday trading. Novartis dipped 1% to $55.01.

"We are disappointed with the FDA's perspective on the program and are working with Novartis to evaluate our options for valopicitabine," said Jean- Pierre Sommadossi, chief executive officer of Cambridge, Massachusetts-headquartered Idenix.

Last year, Novartis exercised its option to license the oral antiviral, Idenix' lead drug candidate, in a deal worth up to $70.0 million in license fees and as much as $455.0 million in milestones (Marketletter April 3, 2006).