Pharmasset halts Hep B trial after adverse events

Pharmasset announced today that the company has halted a late-stage study for its experimental chronic hepatitis B treatment clevudine. According to the the Princeton, NJ based company, a number of cases of mild to moderate muscle weakness were observed in patients involved in the trial. The drug company licensed clevudine from South Korea's Bukwang Pharmaceuticals, where the drug is marketed as Levovir. Pharmassett says it was aware of more severe cases of myopathy in patients involved in clevudine studies in South Korea and after consulting with the FDA and its monitoring board, decided to shut down its trial to avoid more serious adverse reactions.

The news sent Pharmasset's shares tumbling nearly 14 percent in morning trading. Pharmasset says it will continue to monitor patients, but does not plan to include data from the QUASH studies in submissions to regulators. The company will now focus its efforts on its Hepatitis C pipeline.

"While we are obviously disappointed with the outcome, we believe the decision to stop dosing is an appropriate one," stated Schaefer Price, President and CEO. "Our full energy and resources in research and development will now be focused on our promising HCV pipeline. Our partner Roche will shortly initiate dosing in a phase IIb trial with R7128, and will report interim data from the INFORM-1 trial at the upcoming EASL meeting. Pharmasset's unpartnered second generation HCV nucleoside, PSI-7851, is progressing well in a phase I trial and we expect to report the first antiviral data in the second half of 2009. In addition, we are collecting preclinical data from our research efforts to select a purine nucleos(t)ide for clinical development."

- read the Pharmasset release