Only a few days after Merck reported the positive results from the two pivotal Phase III registration studies for its investigational oral hepatitis C protease inhibitor, boceprevir. The spotlight on the stage now shifted the another hepatitis C protease inhibitor, Vertex’s telaprevir.

Vertex announced new clinical data demonstrating this week that nearly all hepatitis C patients who respond early and robustly to treatment with the company’s experimental drug telaprevir achieve a cure after six months — reducing the conventional treatment time for the disease in half. The results come from a phase III study known as ILLUMINATE, which was designed to confirm the theory — long held by Vertex — that telaprevir could help cure hepatitis C patients with 24 weeks of total therapy instead of the 48 weeks of treatment currently considered the standard of care.

Investigators set out to determine if patients who achieved undetectable levels of the virus after four and 12 weeks of treatment would benefit by going past the 24-week mark and push on to 48 weeks of therapy. But they found that subjects with an extended rapid viral response, or eRVR, had a cure rate of 92 percent at 24 weeks and 88 percent at 48 weeks.

“The viral cure rates seen in (the Phase III Illuminate trial) showed that there was no benefit to extending telaprevir-based therapy to 48 weeks for the majority of people,” said Kenneth Sherman, the principal investigator of the trial. “Patients who had a rapid response to telaprevir-based regimens at weeks four and 12 had a high likelihood of achieving a cure with 24 weeks of total treatment, which may provide important information to motivate people to continue therapy.”

Vertex’s HCV drug telaprevir will be the first HCV specific protease inhibitor to offer a real hops for a hepatitis C cure. The virus has infected roughly four million Americans, most of them baby boomers, in addition to 170 million people worldwide. Following the approval of telaprevir, which is expected in early 2011, Merck’s (MRK) drug, boceprevir, would probably be available a few months later. The market is huge and more drugs in this category are required to satisfy its needs.

Vertex plans to release more late-stage data next month in the lead-up to completing their rolling FDA application by the end of this year. Seeking Alpha says it expects an approval of the drug in early 2011 with a huge market to tap.