Cushing’s disease is an uncommon endocrine disorder resulting from a pituitary tumour stimulating excess secretion of cortisol from the adrenal gland. Excess cortisol results in abdominal obesity, hypertension, osteoporosis, depression and increased mortality. It occurs in approximately 8 per million of the population and is more common in women (Broder 2014). The primary treatment is pituitary surgery, however cure is only effected in 40-75% cases depending on the size of the tumour and many patients are left with excess cortisol and a greater than 2-fold increased risk of death (Nieman 2015). Diurnal is testing a new approach to directly treating the pituitary tumour and switching off its stimulation of the adrenal gland. It is anticipated that this treatment will address the increased mortality and poor quality of life in the 25-60% of patients who have residual disease after pituitary surgery or where surgery is contraindicated.

Diurnal owns the Orphan Drug Designation in Europe for a novel, short, interfering RNA (siRNA) oligonucleotide directed against proopiomelanocortin for the treatment of adrenocorticotropin-dependent Cushing's syndrome.

Broder MS, Neary MP, Chang E, Cherepanov D, Ludlam WH. Incidence of Cushing's syndrome and Cushing's disease in commercially-insured patients <65 years old in the United States. Pituitary2015; 18:283-289

Nieman LK, Biller BM, Findling JW, Murad MH, Newell-Price J, Savage MO, Tabarin A, Endocrine S. Treatment of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2015; 100:2807-2831