Side Effect of Low Side Effects: 20% Stock Gain

Side effects are usually a minor concern when treating terminal diseases like cancer. If you're going to die not taking the drug, hair loss, anemia, seizures, or one of the other numerous side effects of cancer treatments are acceptable risks.

But as more drugs become available to treat a disease, the side effects become increasingly important if the increase in life expectancy is approximately the same.

Last November, Medivation (NAS: MDVN) and Astellas Pharma (OTC: ALPMY) said that they were stopping a trial of their prostate cancer drug MDV3100 after an interim look at the data showed the drug was clearly helping patients. The drug increased survival by 4.8 months, which isn't too shabby for a patient population that has a life expectancy of just over a year.

The improvement in survival was similar to Johnson & Johnson's (NYS: JNJ) Zytiga, but the companies held back the side effect profile for a medical meeting; it's hard to get a top spot at a meeting if you're not presenting anything new.

That meeting -- the 2012 Genitourinary Cancers Symposium -- is being held this week, which caused the jump today after Medivation and Astellas released additional data on the safety profile as well as some secondary endpoints. The message: All clear on the home front. The biggest concern -- potential for seizures -- doesn't seem to be a major concern, with just 0.6% of patients exhibiting the side effect.

In addition to helping MDV3100 compete with Zytiga for late-stage patients who have failed Sanofi's (NYS: SNY) Taxotere, the clean side effect profile will help Medivation and Astellas move into earlier patients who haven't been treated with chemotherapy yet. Dendreon's (NAS: DNDN) Provenge, which treats that population, is very tolerable, so there's a high hurdle to reach there.

Of course, efficacy is still king. The stock more than doubled when the top-line data were announced; it's only up a little more than 20% today.

Medivation is the prototypical multibagger, up nearly 400% over the past year. Fool analysts think they've found another health-care company with just as much upside. You can read about it in their new free report: "Discover the Next Rule-Breaking Multibagger." You can get your copy for free by clicking here.

At the time thisarticle was published 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.

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