Repros Therapeutics Inc. (NasdaqCM:RPRX) today announced it has received IRB approval to commence the low dose Proellex® study. The contract for clinical services was previously awarded to ICON. The new low dose study is designed to explore both safety and signals of efficacy in an escalating dose fashion. The study will test 5 different doses of Proellex (1, 3, 6, 9 and 12 mg) with 1 mg being the first dose tested. In previous studies a 12.5 mg dose was well tolerated and yielded statistically significant efficacy signals for both uterine fibroids and endometriosis.
The Company plans to report the results after each patient dosing group has completed the 10 week dosing period. Based on previous work the Company anticipates that all five doses will be safe. Although the Company believes that both the 1 and 3 mg dose will not yield any efficacy signal due to the low levels of projected absorbed drug, those doses were required by the FDA to assure patient safety at higher doses in light of the liver toxicity exhibited at 50 mg. The Company believes that roughly 80% of women at the 12 mg dose will exhibit changes in menstrual patterns that translate to clinical benefit for both uterine fibroids and endometriosis. The benefits expected are significant reduction in menstrual bleeding and reduction in menstrual pelvic pain. Since the Company does not have human experience at doses lower than 12.5 mg it is difficult to project what efficacy signal might be observed below 12 mg.