Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of ZIOPHARM Oncology (NASDAQ:ZIOP), a clinical-stage biopharmaceutical company focused on developing therapies to treat cancer, jumped as much as 17% after announcing the results of preclinical and clinical activity for investigational compound Ad-RTS-IL-12 in an oral presentation at the American Society of Gene and Cell Therapy's annual meeting in Washington D.C.

So what: According to ZIOPHARM's press release, IL-12 gene expression levels can be controlled using Intrexon's (NYSE:XON) RheoSwitch Therapeutic System to essentially "switch on" IL-12 expression and lead to powerful anti-tumor and anti-cancer stem cell effects. As noted, "This immune response is characterized by an increase in tumor infiltrating lymphocytes with system wide immune activation." ZIOPHARM noted positive anti-tumor effects in both phase 1 and 2 for Ad-RTS-IL-12 patients with breast cancer and melanoma in its presentation, as well as a potent anti-cancer effect in a glioma model which demonstrated tumor mass shrinkage and prolonged survival compared to the current standard of treatment. Most importantly, the data showed a reduction in brain cancer stem cells which are believed to be the primary cause of relapse or metastasis.

Now what: As always, keep in mind that these are very early stage results and it's probably not worth getting too excited until we have some tangible efficacy results in a larger pool of patients (i.e., phase 2 studies). I wouldn't, however, fault you for putting ZIOPHARM on your watchlist given that anti-cancer stem cell research is drawing a lot of investments from big pharma. Anti-cancer stem cell therapies also represent one of the first attempts to treat cancer at the source rather than simply trying to manage its proliferation. Today's data is intriguing for sure, but I believe ZIOPHARM is still a volatile and dangerous investment considering that it's wholly clinical-stage and burning through its remaining cash.

ZIOPHARM shares may have soared today, but they'll likely struggle to keep pace with this top stock over the long run
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Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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