After a relatively quiet few months for drug developer InterMune (NASDAQ:ITMN), on Wednesday the Rule Breakers pick announced more early clinical-trial results for its potential hepatitis C drug.

In advance of a major liver-disease conference in November, InterMune and development partner Roche released data and abstracts for protease inhibitior ITMN-191 from several preclinical and phase 1 studies of the drug.

Unlike some of ITMN-191's potential rivals, testing's still in too early a stage to draw definitive conclusions about its efficacy against competitors. That said, its initial results seem roughly comparable to other drugs' preliminary performance. In one 14-day study of patients who'd failed other hepatitis C therapies, ITMN-191 lowered the levels of hepatitis C in patients to roughly the same average level that Vertex's (NASDAQ:VRTX) telaprevir did in one of its first phase 1 studies among a similar patient group.

In Wednesday's release, InterMune also included some preclinical data testing ITMN-191 with other Roche hepatitis C compounds. Ironically, ITMN-191's future might depend as much on the success of one of Roche's hepatitis C partners as on its own.

Over the past several months, Vertex and Schering-Plough (NYSE:SGP) have been amassing mountains of positive clinical-trial data for their own antiviral protease inhibitors, telaprevir and boceprevir, both of which could compete with ITMN-191. InterMune and Roche have an ace up their sleeve, though; they've been testing ITMN-191 in combination with other antiviral polymerase inhibitors from Roche and another Roche partner, Pharmasset (NASDAQ:VRUS).

If Roche's polymerase/protease inhibitor combinations work notably better (and no less safely) than Schering and Vertex's single-therapy approaches,  ITMN-191 could become the protease inhibitor of choice for treating hep C. That will be particularly true if doctors display a preference for drugs proven in combination testing, rather than leaning toward Vertex or Schering's compounds.

Many potential hep C compounds that produced solid preclinical data, like ViroPharma (NASDAQ:VPHM) and Wyeth's (NYSE:WYE) HCV-796, have later been felled by safety issues, so the verdict is still out on ITMN-191's longer-term chances. Whatever the compound's fate, InterMune's immediate future will be shaped more by the phase 3 study results due next January for its pulmonary fibrosis drug pirfenidone. If successful, InterMune could have pirfenidone approved for marketing and on sale in early 2010. In that case, more positive early-stage results for ITMN-191 could be icing on the cake for InterMune investors.

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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.