From: WSJ

Repros Therapeutics (RPRX) said the Food and Drug Administration in a letter doubted whether the company would be able to identify a dosing regimen for Proellex that will be both effective for any of the intended indications and free of an unacceptable risk of serious liver toxicity.

The FDA wants the following information on its Proellex drug application before releasing it from a clinical hold: follow-up information from all subjects treated with Proellex who exhibited any laboratory changes indicative of liver injury; pharmacokinetic analyses to try and identify a serum concentration of Proellex below which there was no increase in liver enzymes; any information regarding the likely mechanism(s) for the Proellex-induced liver toxicity and processes/steps that will be implemented to minimize the risk of liver toxicity; and a dosing regimen to investigate the efficacy of Proellex.

Proellex was developed to treat uterine fibroids and endometriosis.

Repros said it would need to license Proellex if the FDA does allow future development because it doesn't have the resources or time to do so on its own, and also announced that the medical director for oncology, Dr. Stephen Howell, has resigned.