Vertex shares dip ahead of rival study data

The stock fell $1.05, or 4.1 percent, to $24.90, adding to Wednesday's 3.8 percent decline. Shares have traded between $13.84 and $41.42 over the last 52 weeks.

Telaprevir is now in late-stage development but its likely competitor, boceprevir, could enter late-stage development soon. That drug's developer, Schering-Plough Corp., has already submitted a Phase III clinical trial plan with the Food and Drug Administration and plans to release additional study data Saturday at the 43rd Annual Meeting of the European Association for the Study of the Liver (EASL) in Milan.

Analysts have been looking to telaprevir as a possible top-selling hepatitis C treatment, but the market is still unsure of how it would fare against boceprevir.

Shares of Kenilworth, N.J.-based Schering-Plough fell 15 cents to $18.12.

On Thursday, Cambridge, Mass.-based Vertex said telaprevir invoked a response in hepatitis C patients who failed a prior treatment. The data, released at EASL, follows additional midstage study results that show the drug worked in patients who had not received prior treatment and data showing a twice-daily dose worked just as well as the current practice of dosing three times a day.

Hepatitis C can cause liver disease and cancer and affects about 170 million people globally.

Lazard Capital Markets analyst Dr. Terence Flynn reaffirmed a "Hold" rating on Vertex as he awaits Schering-Plough's study data.

"Telaprevir's current profile leaves opportunity for improvement by competitor protease inhibitors (rival drugs) in development, and in our view, it is unlikely to be best in class," he said, in a note to investors.

Rodman & Renshaw analyst Navdeep S. Jaikaria cited the risks involved with the drug while reaffirming a "Market Perform" rating.