Pfizer's (NYSE: PFE) Sutent is on a roll. Unfortunately, it's not the kind that can boost sales and increase the share price. The drug failed another clinical trial yesterday -- this time in liver cancer.

Sutent is already approved for kidney and gastrointestinal cancers and has been shown to work on pancreatic cancer as well. But to boost sales substantially, Pfizer needs to get it approved for another indication.

Things haven't worked out that way. Let's review the bidding: Testing against Roche's Xeloda in breast cancer? Fail. Against Roche's Avastin in combination with Bristol-Myers Squibb's (NYSE: BMY) Taxol? Fail. Against placebo in combination with sanofi-aventis' (NYSE: SNY) Taxotere and another testing it when combined with Roche's Xeloda? Fail, and fail.

Breast cancer is a tough market to break into, but you'd think investors would have had higher hopes for liver cancer. After all, Bayer and Onyx Pharmaceuticals' (Nasdaq: ONXX) Nexavar is approved for kidney cancer, just like Sutent is, while also being approved for liver cancer.

Sutent failed there, too. Pfizer stopped the trial because of higher incidence of serious adverse events and because it was clear that the trial wouldn't be able to show that Sutent was as efficient as Nexavar. The failure is a clear win for Onyx, which rose by nearly 9% today on the news.

Pfizer hasn't given up hope, though. The company is still testing Sutent in lung cancer (good luck) and prostate cancer (another tough one), and as an adjuvant in kidney cancer. The last one, treating kidney cancer patients who have surgery, could be its best option, as Pfizer has already shown that the drug works on patients with advanced kidney cancer.

Of course, Nexavar is in similar trials, so even if Sutent actually breaks its losing streak in the clinical trial realm, that may not translate to a win in the marketplace. It depends on the survival numbers for each drug's clinical trial.

Sutent may not be a winner, but Tom Gardner thinks this stock will remain one.

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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.