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 CytRx (NASDAQ:CYTR), a clinical-stage biopharmaceutical company focused on developing therapies to treat cancer, jumped as much as 14% after the Food and Drug Administration granted the company approval to extend the dosing of aldoxorubicin until disease progression in an upcoming phase 3 trial for soft-tissue sarcomas.

So what: The FDA's ruling is important because its previously outlined phase 3 design under its Special Protocol Assessment had called for treatment, and the study, to be stopped after six cycles. But following CytRx's phase 2b clinical results that utilized a 1,560 mg/m2 dose of doxorubicin, which would have been expected, on paper, to potentially cause cardiac toxicity, no such cardiotoxicities were noted. In other words, with CytRx now being able to dose until disease progression there could be an even greater progression-free survival and median overall survival benefit.

Now what: Everything is in the details, and the FDA's thumbs up to CytRx clearly shows that it likes what it's seen so far in terms of cardiovascular safety from aldoxorubicin. Obviously, there aren't many second-line-treatment options available for soft-tissue sarcomas, so this could be construed as mildly positive news for CytRx. I wouldn't, however, get too excited until I see its pivotal late-stage results, which are targeting a statistically significant improvement in progression-free survival as its primary endpoint.

CytRx is having a great day, but it may struggle to keep up with this top stock in 2014
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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.

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