File this under "P" -- not for Pfizer (NYSE: PFE) or pancreatic cancer, but for potential.

Researchers reported promising finding from a clinical trial of Pfizer's new drug, CP-870,893, in pancreatic cancer patients in the most recent issue of the journal Science. When the drug was combined with Eli Lilly's (NYSE: LLY) Gemzar, patients appear to live longer than would be expected from Gemzar alone.

As you might guess from the name, CP-870,893 is still in early stages of development; it doesn't even have a generic name, let alone a branded one. The trial didn't have a placebo control, so the 5.6 months of progression-free survival can only be compared with the historic figure of 2.3 months. About a quarter of the patients saw their tumors shrink by at least 30%; typically Gemzar alone would only cause about 5% of patients to achieve that.

Comparing results with historical figures instead of matched blinded controls is good for determining if a drug has potential, but a controlled trial will likely be needed before the Food and Drug Administration will approve it.

The most interesting thing about the drug is that it acts like Dendreon's (Nasdaq: DNDN) Provenge and Bristol-Myers Squibb's (NYSE: BMY) ipilimumab to stimulate the patient's immune system to attack the tumor. But researchers found that CP-870,893 actually spurred the immune system to attack the matrix that holds the tumor together. That could mean the drug might work for other types of solid tumors.

But let's not get ahead of ourselves. This was an early trial with a whopping 21 patients tested. There's a market for CP-870,893 if it works, but let's keep this one in the potential file and not pencil in revenue just yet.

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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.