Swiss drug maker Novartis AG said on Wednesday it has won European Union approval for its Signifor as the first medical therapy for Cushing's disease, a rare hormonal disorder.

Signifor, which is designed for Cushing's disease patients who cannot have surgery or for whom surgery has not been successful, had already won a green light from the European Medicines Agency (EMA) in January.

Cushing's is caused by a small tumour of the pituitary gland making too much of a hormone. Standard treatment is surgical removal of the tumour, but this does not always work.