Vertex's Lead Cut Down

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Schering-Plough (NYSE: SGP) is moving forward with its antiviral hepatitis C drug even faster than expected. Although Vertex Pharmaceuticals' (Nasdaq: VRTX) telaprevir was originally going to market substantially sooner than Schering's boceprevir, Shering's most recent move will cut that lead down to almost nothing.

On Wednesday, Schering announced the plans for its phase 3 program with boceprevir, its protease inhibitor. This is significant news for Vertex, because many investors and analysts (like myself) have been counting on telaprevir having some lead to market over boceprevir.

Vertex started its telaprevir phase 3 program in March. Schering's press release was unfortunately light on the details about when exactly its phase 3 program will start enrolling patients, but it is likely to be soon. Both Vertex's and Schering's studies will be dosing individual patients with drugs for the same amount of time (48 weeks), so the phase 3 program that completes its patient enrollment first will likely have the drug that gets to market soonest for newly diagnosed hepatitis C patients.

The hepatitis C genotype 1 standard of care treatment regimens currently consist of either Schering's pegylated interferon (Peg-Intron) or Roche's slightly different interferon (Pegasys). The efficacy and safety of the two drugs are generally very comparable, and this scenario may be playing out with telaprevir and boceprevir as well.

Both Vertex and Schering's pivotal phase 3 studies in newly diagnosed hepatitis C patients will enroll about 1,000 patients. In its respective phase 2 studies, Vertex seemed to have the less strict patient enrollment criteria. If this holds for its respective phase 3 studies, the race to complete the trials will come down to Vertex's several-month enrollment lead and looser enrollment criteria, versus Schering's much greater experience in running hepatitis C studies, thanks to its history with Peg-Intron.

Efficacy, safety, and convenience will ultimately determine the winners and losers in the race to develop the next new hep C drug. While there are some key potential differences in how Schering, Vertex, and Vertex partner Johnson & Johnson (NYSE: JNJ) will be positioning their protease inhibitor hep C drugs to be used, whichever compound is approved first will have some positive marketing advantages compared to the follow-on protease inhibitors.