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 cancer-therapy-focused biopharmaceutical company ZIOPHARM Oncology (NASDAQ:ZIOP) soared as much as 24% after announcing that its Phase 3 study for Palifosfamide reached enough progression-free survival (PFS) events to start analyzing the trial data.

So what: Palifosfamide is being targeted as a first-line treatment for metastatic soft tissue sarcoma and, according to ZIOPHARM, it reached its targeted number of progression-free survival, or PFS, events as outlined in the blinded study. Now, the data will be reviewed by an independent data monitoring committee for efficacy, and ZIOPHARM expects to report top-line results of the drug during the last week of March.

Now what: Obviously, this is a good step in the right direction, but we unfortunately don't know how big that step actually was, which makes buying into today's rally somewhat of a gamble. There could be a number of factors that wind up negating today's rally including the exact PFS improvement, as well as safety and efficacy data relative to placebo. I'd much rather wait for the top-line data in March than play a guessing game of where ZIOPHARM is heading next.

Craving more input? Start by adding ZIOPHARM Oncology to your free and personalized watchlist so you can keep up on the latest news with the company.

Fool contributor 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.

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.