It just keeps getting better.

Not only does adding Vertex Pharmaceuticals' (Nasdaq: VRTX) telaprevir onto the standard of care for hepatitis C increase the likelihood of a sustained viral response -- essentially a cure for patients -- but it allows many patients to take current offerings for less time.

In a phase 3 trial dubbed Illuminate, Vertex compared 24 weeks of treatment with the current standard of 48 weeks. For patients who had undetectable levels of the hepatitis C virus early in treatment -- after four weeks and 12 weeks of treatment -- 92% of them were cured after 24 weeks of treatment compared to 88% cured after taking a full course of 48 weeks.

Cutting the time on the standard of care is a big deal because Roche's Pegasys and Merck's (NYSE: MRK) Pegintron have nasty side effects that make many patients feel horrible. In the trial, 65% of the patients had early response rates that would be eligible for the shortened treatment.

Merck, which is developing competing hepatitis C treatment boceprevir, also tried the same trick of separating out early responders. But Schering-Plough, which owned the drug before Merck bought the company, set up its trial to treat the early responders for 28 weeks, a month longer than Vertex treated its. Merck hasn't broken out the data for just early responders yet, but the cure rate for those who got response-guided therapy was 63%, lower than the 72% for all the patients taking telaprevir.

Vertex has one more phase 3 trial to report about patients who have failed prior hepatitis C treatment. Assuming that trial goes as well as the first two -- first results are expected next month -- Vertex and marketing partner Johnson & Johnson (NYSE: JNJ) should have no problem getting the drug approved and then persuading patients to take it. I wonder if Eli Lilly's (NYSE: LLY) executives cringe at every data release, wondering what could have been.

Vertex is up 240% since the analysts at Motley Fool Rule Breakers recommended it in early 2005. To read the original recommendation and our analysts' current thinking, grab a free 30-day trial subscription to the high-growth newsletter.

Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Johnson & Johnson is a Motley Fool Income Investor selection, and Motley Fool Options recommended buying calls on the stock. The Fool has a disclosure policy.