Repros Therapeutics has begun two clinical studies comparing Androxal to the leading U.S. testosterone replacement therapy. Investigational Review Board approval has been obtained for several of the study sites and an investigator meeting and shipment of drug is scheduled for next week. Several sites have begun pre-screening subjects. The FDA has previously indicated that head-to-head studies could be conducted against approved testosterone products to establish claims for labeling purposes with the proviso that Androxal must show superiority to the testosterone product for any specific claims to be made.

Repros will conduct two identical studies. Each will 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. Men on placebo will receive two placebos, one for each active. The studies will be of 17-week duration, consisting of 16 weeks of dosing and 1 week of follow-up.

The primary endpoint of the study is the comparison of Androxal to the topical gel from the perspective of normalizing testicular function. As such, men must exhibit 24-hour average testosterone levels in the normal range, 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. Based on results from previous studies, the company believes the two trials are suitably powered to demonstrate the key difference between restoration of normal testicular function with Androxal versus the T replacement-induced suppression of male reproductive organ activity. Additional efficacy and safety comparisons will also be made.