Sometime in 2012, Aeterna Zentaris (Nasdaq: AEZS) and Keryx Biopharmaceuticals (Nasdaq: KERX) are going to go up or down substantially. How's that for a prediction that will almost certainly come true?

Why not be more specific? It's complicated.

Unlike with FDA decisions, the timing of clinical trial results isn't clear-cut. In the case of Keryx and Aeterna Zentaris' cancer treatment drug perifosine, the trial will end after 360 deaths in the trial, and then Keryx, which is running the trial, will have to unblind the data and calculate the results. Currently the companies are guiding for results sometime in the first quarter.

Predicting which way the trial will go is complicated by changes that the companies made between the phase 2 and phase 3 trials. A subset of the colon cancer patients in the phase 2 trial looked really good: survival of 15.1 months versus 6.5 months for the control group. So the companies decided to run the phase 3 trial on patients that matched the subset's criteria.

That's a sound move, but the decision was based on results from just 25 patients, and only 14 of those received perifosine; that's not exactly a large data set. Running another phase 2 trial with a larger number of patients -- but smaller than the 430 in the phase 3 trial -- would have been a cheaper way to confirm the hypothesis. Instead, the companies pressed ahead with a phase 3 trial, which will result in perifosine getting on the market quicker if it's a success, but leaves investors a little in the dark as to what the results will be.

No news is good news?
As we get further into the first quarter, you'll start to hear a lot of chatter about how not hearing the results is a good thing. The theory being that the longer wait is because patients taking perifosine are living longer, which makes it more likely that the trial will be a success.

While that's certainly a possibility, there are other potential reasons for a longer-than-expected wait, including that patients taking placebo are living longer. It's hard enough to correctly guess survival times, which is only complicated by the small number of patients in the phase 2 trial with the characteristics of the patients in the phase 3 trial.

Another possibility is that the ending of the trial will have little effect on the difference in the median survival. The trial ends when a certain number of subjects in the trial die, but that can be driven by outliers that survive substantially longer, as Exelixis (Nasdaq: EXEL) saw with its trial for cabozantinib. The median survival time is what the FDA will care about, and by definition it isn't affected by the outliers on either side of the data set.

Plan B
While perifosine colon cancer data is the most important event for both Keryx and Aeterna Zentaris, the companies have backup plans both together and individually.

Perifosine is also in a phase 3 trial for multiple myeloma, a type of blood cancer. There are plenty of examples of drugs that have worked for one cancer type but not another: Pfizer's (NYSE: PFE) Sutent for kidney and other cancers, but not breast, lung, liver, or prostate cancer; Bayer and Onyx Pharmaceuticals' (Nasdaq: ONXX) Nexavar for liver and kidney, but less so for lung cancer. Perifosine failing for colon cancer should give investors less confidence that it will work for multiple myeloma, but not enough to write it off completely.

Keryx has one other drug in development, Zerenex, which treats end-stage renal disease. The drug passed one of its phase 3 trials, and Keryx is waiting on long-term safety and efficacy from a second phase 3 trial before it can submit to the FDA.

Aeterna Zentaris has a packed early-stage pipeline and a couple drugs that are later-stage. AEZS-130 passed its phase 3 trial as a diagnostic for adult growth hormone deficiency. And it has another cancer compound, AEZS-108, that's being tested in numerous phase 2 trials.

The backup plans should help provide some valuation support should perifosine fail for colon cancer, but both companies remain risky going into 2012. If you're looking for something a little less dependent on binary events for next year, check out the Fool's new free report, in which Fool analysts report their top pick for 2012. Just click here to grab your free copy.