Vanilla might not have come up positive, but at least sanofi-aventis (NYSE:SNY) and Regeneron Pharmaceuticals (NASDAQ:REGN) will keep trying to show that aflibercept is capable of helping cancer patients live longer.

On Friday afternoon, the companies said they were stopping a trial, oddly named Vanilla, because an interim look at the data showed that aflibercept in combination with Eli Lilly's (NYSE:LLY) Gemzar wasn't going to increase overall survival in patients with metastatic pancreatic cancer compared with Gemzar alone.

Companies build in these interim peeks at the data to potentially cut their losses and not have to wait until the end of the study to realize that the drug doesn't help patients. Considering the high cost of drug development, cutting their losses is a good thing for patients, companies, and shareholders

While the drug doesn't seem to work for pancreatic cancer patients, sanofi-aventis and Regeneron haven't given up on aflibercept altogether. The drug is still in three other phase 3 trials -- thankfully, none of which are named chocolate or strawberry -- testing it as a first-line treatment for prostate cancer and as second-line treatments for colorectal cancer and non-small cell lung cancer.

In all three trials, aflibercept is being tested in combination with currently approved chemotherapy agents. I like that approach because the drug only has to show an improvement to survival rather than trying to beat the current treatments if the study were a head-to-head trial. Pfizer's (NYSE:PFE) Sutent, for instance, failed to beat Roche's Xeloda and Avastin, in two separate trials, as Pfizer tried to expand Sutent to treat additional tumor types.

Still, as the Vanilla trial shows, adding a treatment is no guarantee you'll avoid a disappointing outcome.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Pfizer is a recommendation of the Inside Value newsletter. The Fool has a disclosure policy.