Pharmasset Falls on Rival Abbott Hepatitis C Therapy Results

Pharmasset Inc. (VRUS), developer of anti- viral medicines, plunged today after Abbott Laboratories (ABT) said interim study results of its rival experimental hepatitis C therapy showed high cure rates.

Shares of Pharmasset, based in Princeton, New Jersey, fell 8.6 percent to $72.54 at the close of New York trading, the biggest single-day decline in nine weeks. The company’s shares have more than tripled this year.

Abbott, based in Abbott Park, Illinois, told investors and analysts today in New York that study results of its hepatitis C drug combination found that patients with the liver infection can be cured without adding interferon to treatment. Investors had expected that Pharmasset’s treatment wouldn’t have competition from a therapy that didn’t use interferon, said Howard Liang, an analyst at Leerink Swann in Boston.

“We are seeing there is another way of achieving a regimen without interferon that looks like it will be competitive,” said Liang in a telephone interview. “It will eventually all boil down to who has the better data.”

New Pharmasset data isn’t expected to be available until April, Liang said.

Abbott released early results of its trial, dubbed PILOT, at the conference. The study found the hepatitis C virus was reduced to undetectable levels in 41 of 42 patients after they were treated with Abbott’s drug combination for three months. At six months, nine of the 10 patients still being monitored showed no sign of the virus.

Abbott Results

Abbott’s hepatitis C therapy promises to “dramatically change the treatment landscape” for the disease, Richard Gonzalez, the company’s executive vice president for pharmaceuticals, said at the investor conference. “We’re on track to show patient cure rates in the 90 percent range.”

The drugmaker told investors it would be able to get its drug combination approved and to market by 2015. Pharmasset hasn’t given a date for release. Abbott’s trial tested four compounds, with each patient getting a combination of three. Pharmasset uses two.

“The two-drug combination has a better chance of a very clean safety profile,” Brian Skorney, an analyst at Brean Murray Carret & Co. LLC in New York, said in a telephone interview. “I continue to believe Pharmasset’s will be better.”

Richard E.T. Smith, Pharmasset’s vice president of investor relations and corporate communications, failed to return a telephone call placed to the company.

To contact the reporter on this story: Pat Wechsler in New York at pwechsler@bloomberg.net

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net