Vertex Pharmaceuticals' ( VRTX) experimental hepatitis C drug telaprevir is capable of significantly improving cure rates in the most difficult-to-treat patients, according to final results from a phase II study released Wednesday afternoon. The new data come from Vertex's PROVE 3 study, which enrolled 453 patients who had failed prior treatment with the current standard drug regimen for hepatitis C -- a 48-week course of long-acting interferon plus ribavirin. In the phase II study, these patients were randomized to receive either treatment with a combination of telaprevir plus the standard therapy or retreatment with the standard therapy alone. In all, 51% of patients treated with a 24-week regimen that included 12 weeks of telaprevir reported undetectable levels of the hepatitis C virus six months after treatment. In hepatitis C parlance, that's known as a sustained virologic response, or SVR. Simply stated, these patients are considered cured of hepatitis C. By comparison, only 14% of the patients retreated with 48 weeks of standard therapy alone achieved an SVR, or cure, six months after treatment. The final data from the PROVE 3 study was released online Wednesday in a research abstract ahead of next month's meeting of the European Association for the Study of the Liver (EASL), one of two important scientific meetings held each year devoted to hepatitis C research. Researchers had previously presented the PROVE 3 results from patients treated with telaprevir, but Wednesday's research abstract was the first time data was made public on the patients in the study's control arm retreated with standard therapy alone.