The marathon race to bring the next hepatitis C drug to the market is coming to a close. In the last couple of weeks, both Schering-Plough (NYSE:SGP) and Vertex Pharmaceuticals (NASDAQ:VRTX) have announced that their phase 3 trials have finished enrolling patients.

That means investors can pretty much guess when data from the trials should be available. The timetable for hepatitis C trials is pretty clear, unlike cancer drugs, where the trials often conclude when enough events, like deaths or progression of the disease, have taken place, which makes the timing of their conclusion somewhat unpredictable. For instance, the results of Dendreon's (NASDAQ:DNDN) prostate cancer treatment Provenge are now expected a few months earlier than originally planned.

Almost there
Schering's Sprint-2 trial testing boceprevir and Vertex's Illuminate trial testing telaprevir have a maximum of 48 weeks of treatment and a 24-week follow up to see if the virus has been eradicated, so the subjects that just started treatment now should be done in about 17 months. Add a month or two to process the data, and investors should get results before the end of the summer next year.

Both companies are also testing the drug in patients who have failed the current treatments: Roche's Pegasys and Schering's Pegintron. Vertex is expecting final data from a phase 2 trial, confusingly called Prove 3, in the first half of this year. It's still a possibility that the company could file a marketing application with just that data given the unmet need, but the company needs to see the data and discuss it with the Food and Drug Administration first. If it can get approved with the phase 2 data, great -- Vertex would likely be first to market. But if that doesn't work out, it has a backup plan with a phase 3 trial that is expected to be fully enrolled this quarter. Schering's phase 3 trial for treatment-failure patients concluded enrollment last November.

Watch your back
Telaprevir and boceprevir are the two drugs getting the most attention, but Vertex and Schering aren't the only ones developing drugs to fight hepatitis C.

There are two drugs in development that are hoping to upstage the current treatment (Pegasys and Pegintron). Human Genome Sciences' (NASDAQ:HGSI) Albuferon has already proven itself as effective as Pegasys in treating patients infected with the easier-to-treat genotype 2 and 3 virus. Investors should find out in March whether it's effective against the harder-to-treat genotype 1 infection. Fortunately, Albuferon only has to prove that it's as effective as Pegasys to get approved since the drug is dosed half as often.

ZymoGenetics' (NASDAQ:ZGEN) PEG-interferon lambda is farther back in the clinic -- it recently completed a phase 1 trial -- but the drug is showing a lot of promise. So much promise, in fact, that Bristol-Myers Squibb (NYSE:BMY) licensed the drug for $105 million upfront and another $1 billion in milestone payments if the drug is successful in the clinic, approved by regulatory authorities for various indications, and reaches sales goals. For a phase 1 drug, that high price tag says a lot about how much potential Bristol-Myers thinks the drug has.

There are also other drugs set up to be used with the current treatment's pegylated interferons, rather than replace them. Roche, InterMune (NASDAQ:ITMN), and Pharmasset all have drugs that are further behind telaprevir and boceprevir, but hope to prove superior by the time they conclude their phase 3 trials.

A long road
Hepatitis C is clearly a large market -- Pegintron and Pegasys combined for around $1.7 billion in sales through the first nine months of last year. The first company to hit the market with a new drug will have a clear advantage, but it doesn't look like it'll last for very long. In the drug world, there's always someone on your tail.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.