This past weekend concluded the European Association for the Study of the Liver (EASL) conference, one of the top two annual disease-related conferences. Data presentations at such gatherings usually lead to both winners and losers, but this conference seemed to produce more of the former than the latter.

While much of the new hepatitis-C-drug developments at EASL and in the past month focused on protease inhibitors from InterMune (Nasdaq: ITMN) and others, development-stage drugmaker Pharmasset (Nasdaq: VRUS) also presented strong early-stage clinical data on its lead polymerase inhibitor, R7128.

In a phase 1 study, a combination of R7128 and one of the current standard hepatitis C treatments consistently worked as well as some of the other top potential antiviral therapies, like Vertex Pharmaceuticals' (Nasdaq: VRTX) telaprevir, after similar amounts of time in the clinic.

For example, 17 of the study's 20 patients in one R7128 treatment group had an undetectable amount of the hepatitis C virus (HCV) in their bloodstreams after four weeks of treatment, compared to only 10% of patients in the control group. In a comparable patient population at this stage of development in 2006, telaprevir produced undetectable HCV levels in 12 out of 12 patients.

Pharmasset shares have traded all over the place in the past year, as its prospects have zigged and zagged in relation to its rivals'. The company shouldn't get cocky about R7128 yet; in the last few years, competing drugmakers such as Wyeth (NYSE: WYE) produced similarly good early-stage efficacy data for hepatitis C drugs, only to get bounced out of contention because of safety issues with their compounds. For the long term, R7128 remains a mystery, but for now, the early efficacy results look quite excellent.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has an A+ disclosure policy.