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 Repros Therapeutics (NASDAQ:RPRX), a clinical-stage biopharmaceutical company focused on therapies to treat hormonal and reproductive system disorders, rallied as much as 23% after meeting with the Food and Drug Administration and discussing the future of its testosterone drug Androxal for secondary hypogonadism.

So what: According to Repros' press release, it expects to submit its new drug application for Androxal prior to the end of 2014. Furthermore, the company notes that "no additional safety assessments are currently planned prior to NDA submission." The press release also points out that the FDA has requested additional info regarding endpoints that Repros will use to confirm the maintenance of fertility by semen assessments in two ongoing studies, and that it'll supply these endpoints while enrollment is ongoing.

Now what: Long story short, the reason Repros is roaring higher relates to the FDA's original implication in October that it may need to run a year's worth of safety data on the highest dose of Androxal, causing it to delay its NDA filing. With the need for additional safety studies now on the backburner, and the company able to provide endpoint data to the FDA while concurrently completing enrollment in the aforementioned two studies, the timeline for Androxal's possible approval just got bumped forward. Admittedly, the testosterone drug market is flooded with competitors, but most peak sales estimates project that Androxal could bring in $400 million-$475 million annually. With Repros only valued at $420 million after today's pop (at the time of this writing), an eventual approval could still leave the company with significant upside.

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. The Motley Fool has no position in any of the stocks mentioned. 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.