US regulators have given the green light to Corcept Therapeutics' Korlym, a drug with the same active ingredient as abortion pill RU-486, to treat Cushing’s Syndrome, a rare hormone disorder caused by too much exposure to cortisol.

Specifically, the US Food and Drug Administration has approved Korlym (mifepristone) to control hyperglycaemia secondary to hypercortisolism in adults with endogenous Cushing's syndrome who have type 2 diabetes or glucose intolerance and are not suitable for surgery. The thumbs-up is based on data from a 24-week Phase III study of 50 patients.

Korlym is the first drug to be approved for Cushing’s syndrome which most commonly affects women between 25 and 50. Corcept says it affects 20,000 people in the USA, while the FDA notes that about 5,000 patients will be eligible for treatment with Korlym, which has an orphan drug designation.

Mifepristone has been controversial when used for abortions, especially from pro-life groups in the USA. The FDA notes that Korlym will carry a boxed warning, informing patients that the therapy will terminate a pregnancy.

Corcept chief executive Joseph Belanoff noted that "a relatively small number of endocrinologists regularly treat patients with Cushing's syndrome". As such, "these doctors can be reached without a large sales and marketing infrastructure", and Korlym will be available by May 1.

In Europe, regulators recently recommended approval of Novartis' Signifor (pasireotide) for Cushing's Syndrome.