Vertex Pharmaceuticals Inc. (VTRX) on Tuesday reported interim results from an early stage trial that indicate its experimental oral hepatitis C (search) virus treatment was well tolerated and demonstrated potent antiviral activity.

The results sparked a 14 percent jump in Vertex shares in premarket activity.

The study enrolled 34 patients with chronic genotype 1 hepatitis C virus (HCV) infection who were treated for 14 days with placebo or one of three dose regimens of the Vertex treatment, known as VX-950 (search).

Genotype 1 HCV infection is the most difficult strain of HCV to treat and the most prevalent strain in the United States, Western Europe and Japan.

Patients receiving 750 mg of VX-950 every eight hours achieved a median reduction of the virus equivalent to a more than 10,000-fold decrease in viral levels at the end of 14 days of treatment, Vertex said.

The company reported a median reduction in each of the other two VX-950 dose groups at the end of 14 days of treatment, and said every patient receiving the treatment achieved reduction in HCV levels within the first three days of treatment.

Based on the results of the Phase Ib clinical study, Vertex said it plans to explore the development of VX-950 as monotherapy and in combination with other hepatitis C virus treatments.

Vertex said it expects to file an investigational new drug application in the second half of 2005 to support Phase II clinical development of VX-950 in the United States. In collaboration with Vertex, Mitsubishi Pharma Corp. is developing VX-950 in Japan and certain countries in Asia.

Results from the study will be presented by a clinical investigator on May 17 at the Digestive Disease Week medical conference in Chicago.