( A at week 20 of post-treatmentfollow-u...)Interim Results Presented at EASL from PROVE 1 Clinical Trial of,Investigational Drug Telaprevir in Patients with Genotype 1,Hepatitis C,Health

Interim 12-Week Safety Analysis of PROVE 1

In PROVE 1, the types of adverse events that have been commonly observed with interferon and ribavirin were seen across all treatment arms. The most common adverse events, regardless of treatment assignment, were fatigue, rash, headache and nausea. Gastrointestinal disorders, rash and anemia were more common in the telaprevir arms.

In the telaprevir dosing arms, the incidence of treatment discontinuations due to adverse events through 12 weeks was 11% (19 of 175 patients), compared to 3% (2 of 75 patients) in the control arm. The difference between the two groups is due to the greater number of discontinuations due to rash, gastrointestinal disorders and anemia in the telaprevir arms compared to the control arm. The most common reason for treatment discontinuation in the telaprevir arms was rash (7 patients), and the median time to discontinuation in these patients was 64 days.

Webcast of Investor Presentation

Vertex intends to provide a live webcast of its investor presentation from Barcelona beginning at 7:30 p.m. CEST (1:30 p.m. EDT) on Saturday, April 14. The presentation may be accessed from the 'Events Calendar' on the homepage of Vertex's website at www.vrtx.com. A replay of the webcast will also be available on the Company's website until April 27, 2007. To ensure a timely connection, it is recommended that users register at least 15 minutes prior to the scheduled webcast.

About Telaprevir (VX-950)

Telaprevir (VX-950) is an investigational oral inhibitor of HCV protease, an enzyme essential for viral replication, and is one of the most advanced investigational agents in development that specifically targets HCV. Vertex is conducting a global Phase 2b clinical development program for telaprevir consis
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