Achillion Hepatitis C Drug Trial on Hold on Liver Concern

Achillion Pharmaceuticals Inc. fell the most in six years after a trial of one of its experimental hepatitis C drugs was delayed because of abnormal liver results.

Achillion declined 25 percent to $6.26 at the close in New York, its biggest one-day loss since February 2007.

U.S. regulators put the hepatitis C drug trial on hold after some patients experienced elevated liver enzymes, Achillion said in a statement yesterday. The elevations were observed in healthy patients when Achillion’s sovaprevir was combined with two medicines used to treat HIV infections in order to test for possible drug interactions. The combination may have resulted in a drug interaction that produced higher-than-expected blood levels of the therapies, Achillion said.

“Achillion voluntarily stopped further dosing” and “promptly notified” the Food and Drug Administration of the finding in the early-stage trial involving sovaprevir, the New Haven, Connecticut-based company said. The hold doesn’t affect a current second-stage study of the drug in hepatitis C patients.

Achillion has three drugs in clinical testing for hepatitis C, a liver disease that affects 170 million people worldwide. The company said April 23 that one of the treatments, ACH-3102, appeared effective in five out of eight patients, reducing the amount of the liver-destroying virus in their bloodstream to undetectable levels after 12 weeks of treatment.

Achillion is competing with drugmakers including AbbVie Inc. and Gilead Sciences Inc. to develop new treatments for the disease, a market analysts’ estimate may be $20 billion.

To resolve the hold, the regulatory agency has asked for data from two drug interaction studies as well as a safety analysis of continuing sovaprevir studies, which the company said it plans to provide in about six weeks.

Achillion shares had gained 35 percent in the past 12 months through yesterday.