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 developing therapies to treat hormonal and reproductive system disorders, rocketed higher by as much as 21% after the company announced positive trial data for its lead drug, Androxal, an oral treatment for secondary hypogonadism, after the closing bell Wednesday night.

So what: According to the top-line analysis of its study, which pitted Androxal against AbbVie's (NYSE:ABBV) AndroGel, Repros' Androxal exhibited superiority to AndroGel in both of its co-primary endpoints and a number of secondary endpoints. The two primary endpoints included the percentage change in baseline in sperm concentration, and the percentage of responders to the therapy. Overall, Androxal subjects witnessed their sperm concentration increase 5.9%, while AndroGel-treated patients demonstrated a 33.3% reduction from baseline. Furthermore, the responder rate for AndroGel was just 33.3% compared to Androxal which produced a responder rate of 65.9%.

Key secondary endpoints that were met, according to the press release, include "change in the important pituitary signaling hormones LH and FSH; percent of subjects that become severely oligospermic (< 10 million sperm/mL); induction of hormone dependence via assessment of morning testosterone levels comparing baseline to one week after the end of dosing; and impact on testicular size at the end of the dosing period."

With Androxal also shown to be safe and tolerable in its head-to-head against AndroGel, Repros notes that it believes it has enough data to back a new drug application submission to the Food and Drug Administration by the end of this year.

Now what: Based on today's head-to-head data it would appear that Repros' Androxal is superior in many ways to AndroGel. This is an important finding because treating low testosterone is an extremely crowded market, and the FDA hasn't been willing to let therapies that provide no improvement over existing low testosterone drugs onto pharmacy shelves.

For some idea of the market share that Androxal could be looking at if it's approved, AbbVie's AndroGel has brought in $472 million through the first-half of 2014. If Androxal is able to even garner half of that amount it'd be valued (based on its current price) at one times peak sales estimates, which for those who follow the biotech industry regularly know is fairly inexpensive.

Keep in mind there are still regulatory hurdles to overcome here in that no experimental drug is a "sure thing" to be approved by the FDA. Also, launching a drug into a very crowded market for a company with smaller pockets and a less experienced sales staff than many of its peers could make for a bumpy ride for shareholders. Either way, I'm certainly intrigued after today's results and am keeping a close eye on Repros going forward.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.