Both Aeterna Zentaris (Nasdaq: AEZS) and Keryx Biopharmaceuticals (Nasdaq: KERX) ended yesterday a few percentage points higher than the Dow Jones Industrial Index (INDEX: ^DJI) or the iShares Nasdaq Biotech ETF (Nasdaq: IBB) after phase 2 data from the companies' cancer drug perifosine was published in the online edition of the Journal of Clinical Oncology.

While I encourage all investors to read articles that companies publish in scientific journals -- they're peer-reviewed, which is more than you can say about data in press releases -- in the case of perifosine's phase 2 data, it may not do much to help predict the likelihood of a positive phase 3 trial.

The phase 2 trial tested perifosine in combination with Xeloda as a second- or third-line therapy, but the phase 3 trial is enrolling only patients who have "failed available therapy for the treatment of advanced colorectal cancer," which includes a laundry list of drugs from Pfizer's (NYSE: PFE) Camptosar, which is available as a generic, to newer medications such as Bristol-Myers Squibb and Eli Lilly's (NYSE: LLY) Erbitux and Amgen's (Nasdaq: AMGN) Vectibix if the patients are eligible to take them.

The decision to narrow the entry criteria will help produce data quicker, since last-resort patients don't survive as long; the trial is expected to finish in the first quarter of next year. And it'll help with sales, since there won't be anyone to compete with. But it makes it more difficult to predict the results of the phase 3 trial.

The paper did look at patients who had failed fluorouracil treated patients, one of the types of drugs that patients must have failed to enter the phase 3 trial. The improvement in survival was impressive, but it's a subset analysis of an already fairly small 38-patient trial, so investors shouldn't assume that the phase 3 trial will turn out quite as impressive.

I think there's reason to be cautiously optimistic based on the phase 2 data. Hopefully, Aeterna and Keryx haven't jinxed the perifosine by naming the phase 3 trial "X-PECT" (Xeloda + Perifosine Evaluation in Colorectal cancer Treatment).

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Fool contributor Brian Orelli holds no position in any company mentioned. Check out his holdings and a short bio. Motley Fool newsletter services have recommended buying shares of Pfizer. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.