It's been a quiet few weeks for hepatitis C-focused drugmakers such as InterMune (Nasdaq: ITMN) since the American Association for the Study of Liver Disease conference in November. Yesterday, the Rule Breakers pick updated investors on the progress of its lead hepatitis C virus (HCV) protease inhibitor drug candidate in conjunction with its JP Morgan Healthcare conference presentation.

InterMune's anti-HCV drug, ITMN-191, is not its lead drug candidate; that distinction goes to its idiopathic pulmonary fibrosis phase 3 drug candidate, pirfenidone. But ITMN-191 has captured the focus of many investors because HCV is the next major infectious disease ripe for drug innovation.

ITMN-191, which InterMune in-licensed from Array BioPharma (Nasdaq: ARRY), is currently in phase 1 testing in patients infected with HCV genotype 1. The drug has already completed an earlier phase 1 trial in non-HCV-infected individuals. InterMune announced yesterday that this second phase 1 trial is still set to produce top-line results sometime in the first quarter of this year.

The good news that InterMune gave yesterday is that the 14-day phase 1 trial will be expanded to include higher doses of ITMN-191, and that combination treatment with Roche's already-approved interferon, Pegasys, is expected to begin in the second quarter.

This means that InterMune and partner Roche haven't seen any ominous safety issues with the drug yet, which is a good sign, because higher doses of ITMN-191 should result in lower hepatitis C viral loads.

With no efficacy data on ITMN-191 out yet, we really have no idea (outside the preclinical potency data) how the drug stacks up against much more advanced HCV protease and polymerase inhibitors from competitors such as Vertex Pharmaceuticals (Nasdaq: VRTX), Schering-Plough (NYSE: SGP), and even its own partner, Roche.

Equally as important, we still have no idea about the safety of ITMN-191 in longer-term dosing. Multiple HCV small-molecule compounds have showed no major safety issues in short-term testing, but subsequently faced liver toxicity and other issues after being studied in longer clinical trials.

Unfortunately, I estimate that we'll have to wait for the end of 2008 -- or, more likely, until 2009 -- before we get to see even intermediate-term dosing of ITMN-191. Likewise, I believe it will be the end of 2009 by the time longer-term virologic response data from later studies comes in. Nonetheless, the phase 1 efficacy data that we get to see this quarter will be the first step in showing whether InterMune has a viable drug candidate on its hands with ITMN-191.

InterMune, Vertex, and Array are active picks of our Rule Breakers newsletter.

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