The study is being conducted at various US clinical sites. As of this date 158 men have been enrolled in ZA-300 and 62 men have completed 6 weeks of treatment at the 12.5 mg dose.
In general, the population of men studied in ZA-300 is identical to the population in the pivotal studies with the exception that they may be current testosterone users who have refrained from testosterone use for an appropriate wash out period and there is no sperm count entry requirement.
Repros Believes Early Results from ZA-300 May Be Predictive of Positive Outcome for Pivotal Studies
For the first 62 men that have completed dosing at the lower 12.5 mg dose, 80.6% of men have exhibited testosterone levels above 300 ng/dL after 6 weeks of treatment which exceeds the pivotal study criteria for success. None of the men have exhibited testosterone levels outside of the normal range. The mean testosterone level at baseline was 206 ng/dL and at the end of the 6 weeks the mean rose to 428 ng/dL (pairwise comparison of week 6 results to baseline yielded a p value of < 0.00001). This data is in line with previous Repros Androxal studies. The Company believes many of the men that did not achieve a testosterone level of 300 ng/dL will experience an improvement when they up-titrate to the 25 mg dose. The Company plans to update the findings from the ZA-300 study as warranted by the data.One Year DEXA Study (ZA-303) The Company has also begun enrollment in the one year DEXA study to determine effects of Androxal on bone mineral density. The study is being conducted at various US sites. Repros believes that Androxal will have no negative impact on bone and previous studies have shown improvement in markers of bone turnover. The ZA-303 study, due to its duration, is on the NDA critical path. Depending on recruitment into this study, the Company currently believes it can submit the NDA during the first half of 2014.