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An experimental hepatitis C drug from Vertex Pharmaceuticals VRTX can knock back the virus even in the most difficult-to-treat patients, according to results from a clinical trial announced Monday. The news sent Vertex shares up 63 cents, or 2%, to $32.87 in recent trading Monday morning. The Vertex drug, telaprevir, was able to reduce levels of the hepatitis C virus down to undetectable levels in 52% of so called non-responder or relapse patients. These are patients considered the hardest to treat because they either did not respond to current drugs like interferon and ribavirin, or their virus returned after treatment. Based on previous studies, roughly 10% of treatment-resistant hepatitis C patients who are then retreated with interferon and ribavirin are successfully cured of their disease. The new data on telaprevir come from the PROVE 3 study, a phase II clinical trial that enrolled 453 hepatitis C patients who failed to respond to prior treatment. This is an interim analysis, which means that, to date, telaprevir patients have only been followed for 12 weeks post-treatment. A hepatitis C patient is not considered "cured" of the disease until they have undetectable viral levels 24 weeks, or six months, after treatment.
A Race for Market Share
Based on these results, Vertex and partner Johnson & Johnson JNJ said Monday that they will start a pivotal phase III study in treatment-failure patients during the third quarter. There has been great market speculation whether Vertex might be able to seek regulatory approval for telaprevir based on PROVE 3 data alone, however. John Alam, Vertex's chief medical officer, says it is still too early to comment on the company's ultimate plans for telaprevir in treatment-failure patients. The company intends on sharing final data from PROVE 3 with the U.S. Food and Drug Administration by the end of the year or early 2009. In the meantime, Vertex and Johnson & Johnson are moving ahead on finalizing the design for the phase III study of telaprevir in treatment-failure patients, Alam said. If telaprevir is found to be effective for these hardest-to-treat hepatitis C patients, the commercial potential for Vertex is significant. There are an estimated 250,000 to 300,000 hepatitis C patients in the U.S. who have failed current interferon-ribavirin therapy and are waiting for something new and more effective to be approved so they can be retreated, and hopefully cured. This is one of the major reasons why the race to develop and market a new hepatitis C drug is so frenzied. Vertex and J&J are facing off with companies like Schering-Plough SGP, InterMune ITMN, Roche and Pharmasset VRUS -- all of which are hoping that their respective hepatitis C drugs are superior or can be approved first to be the go-to drug for treatment-resistant patients. A phase III study of telaprevir in hepatitis C patients not previously treated is underway, with data expected in the first half of 2010. If positive, Vertex plans to seek regulatory approval in the second half of 2010. PROVE 3 Data Breakdown
Breaking down the PROVE 3 interim results further, 41% of telaprevir-treated patients who had previously not responded at all to standard treatment (non-responders) reached undetectable levels of viral load at 12 weeks post treatment. For those patients who did respond to standard treatment but then relapsed during follow-up, treatment with telaprevir led to an undetectable viral load rate of 73% after 12 weeks of follow-up. Patients were treated with 12 weeks of telaprevir plus interferon and ribavirin, followed by another 12 weeks of interferon and ribavirin alone. There is a control arm in the PROVE 3 study, but these patients are still being followed. At this point, 8% of these patients retreated with standard therapy (interferon and ribavirin) had undetectable levels of virus after 12 weeks of treatment. After 36 weeks of treatment, the undetectable level rose to 30%. While the control arm patients appear to be doing better with longer re-treatment, Vertex's Alam says most of these difficult-to-treat patients must reach undetectable levels by week 12 if they have any real chance for a long-term cure. Most of the patients who reach undetectable levels after 12 weeks of treatment ultimately relapse again, he says. http://www.hcvadvocate.org
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