Repros Therapeutics has reached the enrollment goal of 120 subjects in the first of two previously announced head-to-head studies comparing Androxal to the leading US testosterone replacement therapy. The two studies were initiated on January 12, 2014.

Each study is designed to enroll 120 men, 40 each into three parallel arms: Androxal, approved topical gel and placebo. All three arms will be blinded and "double dummied," meaning men will receive both an active dose and a placebo mimicking the other active. The studies will be of 17 week duration, 16 weeks dosing and 1 week follow-up.

Men (= 60 years of age) enrolled in the study must exhibit sperm counts in the normal range at baseline ( > 15 million/mL) on two separate days separated by at least two days. Men also must exhibit morning testosterones of < 300 ng/dL on both of those days to be eligible to enter the study.

The primary endpoints of the study are the composite endpoint showing that Androxal is superior to both placebo and the topical gel in the proportion of subjects who achieve both a normal testosterone level and a normal sperm concentration, and the equivalence of Androxal to placebo in the proportion of subjects who experience an end of study sperm concentration below 15 million/mL. These endpoints will provide a comparison of Androxal to the topical gel from the perspective of normalising testicular function. As such, men must exhibit normal 24 hour average testosterone levels in the normal range (300-1040 ng/dL), and an average of two sperm counts at the end of the study must remain above the lower bound of the 95% confidence interval for normal male fertility (15 million/mL). Based on results from previous Repros studies, the Company believes the two trials are suitably powered (90% power, alpha=0.05) to demonstrate the key difference between restoration of normal testicular function with Androxal versus the suppression of male reproductive organ activity typically induced by hormone replacement therapy.

A variety of different efficacy and safety comparisons will also be made. These include excursions of testosterone outside of the normal range as well as impact on testosterone levels after study drug is stopped. Safety assessments will include impact on hematocrit, an important cardiovascular safety marker.

This first fully enrolled study, ZA-305, was recruited at 10 clinical sites. The second study, ZA-304, is expected to fully enroll in the next few weeks.

Joseph Podolski, president and chief executive officer of Repros Therapeutics, commented, "We are very pleased with the effort of our internal clinical team, the clinical sites involved in the study as well as the clinical supplies contractor. It was no small effort to organise and deliver a complicated study that includes placebo for both a gel and capsule product." He further noted, "We further commend the input from our key opinion leader panel in helping to design the study and our own regulatory/clinical QA group for designing and implementing effective instruments that allowed for rapid screening and selection of appropriate study subjects."