Updates with stock price.

CAMBRIDGE, Mass. ( TheStreet) -- Vertex Pharmaceuticals ( VRTX) released new late-stage clinical data Tuesday demonstrating that 65% of hepatitis C patients whose prior therapy was unsuccessful were able to later achieve a viral cure following treatment with the company's experimental drug telaprevir plus the current standard of care.

By comparison, only 17% of these hard-to-treat hepatitis C patients were cured after being treated again with the current standard of care -- long-acting interferon plus ribavirin. The results were statistically significant.

The news helped Vertex shares move almost 3% higher to $36 in Tuesday's after-hours trading session. In advance of the data, Vertex fell almost 3% to $35.01.

These results come from the last of three major phase III studies of telaprevir conducted by Vertex and partner Johnson & Johnson ( JNJ). Previous, positive results from the other two late-stage telaprevir studies in newly treated hepatitis C patients were released in May and August. The companies intend to seek regulatory approval for telaprevir later this year.

This last phase III study, dubbed "Realize," was set up to confirm previous, earlier findings that showed telaprevir could cure a significant number of hepatitis C patients without treatment options because they failed to respond to the current standard of care.

The Realize study enrolled 662 so-called treatment resistant hepatitis C patients split into three different groups: Those who respond to treatment but then relapse during the follow-up period; patients who partially respond to treatment but whose virus never completely disappears; and patients who never respond well to treatment at all.

Since these patients have a form of the hepatitis C virus that is more stubborn or harder to treat, Vertex extended the total treatment duration in the Realize study to 48 weeks, compared to just 24 weeks in the previous studies of newly treated patients. Like in other studies, telaprevir was still dosed for only 12 weeks.

The overall results showed that 65% of patients treated with telaprevir plus the standard of care achieved a cure, or sustained viral response, compared to 17% of patients in the control arm who were re-treated with just the standard of care.

Breaking the results down into the different groups, 86% of relapsers were cured after telaprevir treatment compared to 24% in the control arm.

Among partial responders, the cure rate for the telaprevir-treated patients was 57% compared to 15% for the control arm.

Finally, in the null responder patients, the most difficult to treat patients, telaprevir achieved a 31% cure rate compared to 5% for the control arm.

Results across all three patients types were statistically significant in favor of telaprevir over standard of care.

Wall Street has been waiting for the data from the Realize study, generally expecting overall cure rates for telaprevir in the 60-70% range. The data are important because the competitive race towards approval of the first new hepatitis C drug that acts directly against the virus is heating up.

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