TIBOTEC BEGINS STUDY OF HEPATITIS C PROTEASE INHIBITOR

Medivir, on behalf of the Tibotec and Medivir collaborative project, announced that Tibotec has initiated a clinical trial with a potent and selective hepatitis C virus (HCV) NS3/4A protease inhibitor for the treatment of chronic HCV infection. The Phase Ia clinical trial is designed to assess the safety, tolerability and pharmacokinetics in healthy volunteers. The study will be conducted in Europe.

The preclinical research conducted on the clinical candidate demonstrated favorable characteristics in potency, cross-resistance profiles and pharmacokinetic properties, supporting the exploration of oral dosing in the clinical trials.

This milestone triggers a payment by Tibotec of 2.5 million euros to Medivir.

In November 2004 Tibotec and Medivir signed a license and research collaboration agreement to discover and develop inhibitors of the HCV NS3/4A protease. This novel series of potent HCV protease inhibitors exhibit antiviral properties in a cell-based assay and have drug-like properties.

The NS3 gene product is an enzyme with multiple functions, including polyprotein processing. The enzyme cleaves four sites within the polyprotein, yielding the NS3, 4A, 4B, 5A and 5B proteins. The NS4A protein is a critical cofactor for NS3 HCV protease activity.