Aeterna Zentaris' (Nasdaq: AEZS) investors got a bit of good news yesterday while they wait for phase 3 data for the company's colorectal cancer drug perifosine. AEZS-108 might serve as a backup compound if perifosine fails. Or better yet, maybe it's a second compound on the market if perifosine succeeds.

Maybe. This was only phase 1 data after all.

The purpose of the phase 1 prostate cancer trial is to figure out the right dose of AEZS-108 to use, but the efficacy data doesn't look too shabby. Half of the patients saw their PSA -- a measure of the severity of the prostate cancer -- go down, and out of the four patients with radiologic disease that could be evaluated, three showed signs of stable disease.

Of course, with any phase 1 trial, you have to keep this in perspective. It's only 10 patients. A lot can happen between now and a phase 3 trial with hundreds.

And even if AEZS-108 gets to the market in a few years, there's plenty of competition ahead of it. The phase 1 trial tested patients with castration and taxane-resistant prostate cancer. Assuming Aeterna Zentaris sticks with that patient population, AEZS-108 wouldn't have to compete with Dendreon's (Nasdaq: DNDN) Provenge, which is used before taxanes. But there'll still be competition from Johnson & Johnson's (NYSE: JNJ) Zytiga and Sanofi's (NYSE: SNY) Jevtana, which are used later in disease progression. And Medivation's (Nasdaq: MDVN) MDV3100 and Bayer and Algeta's Alpharadin are also well ahead of AEZS-108 in the prostate cancer space.

Not that competition in the prostate cancer space a few years from now should be investors' biggest worry. Getting perifosine approved by marketing partner Keryx Biopharmaceuticals (Nasdaq: KERX) is the key to Aeterna Zentaris' short- to mid-term success. I think perifosine has a good chance at succeeding, but there are no guarantees in drug development. At least the backup drug will offer some consolation if perifosine's phase 3 data doesn't turn out like investors are hoping.

Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Dendreon and Johnson & Johnson. Motley Fool newsletter services have recommended buying shares of and creating a diagonal call position in Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not 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.