Osilodrostat - an emerging drug for the medical management of Cushing's disease.

Cushing's disease (CD) is a rare endocrine disorder characterized by the overproduction of adrenocorticotropic hormone (ACTH) by pituitary adenoma followed by hypercortisolaemia with severe complications. Although transsphenoidal resection of the defined pituitary adenoma has been the treatment of choice for the past decades, it does not always result in long-term remission - 10-30% of cases show ineffective surgical treatment or tumour recurrence even after initial success. Pharmacological therapies for cortisol reduction are often required for those who either cannot undergo pituitary surgery or when the surgery has failed, and patients still present with the persistent disease. Osilodrostat is a potent oral steroidogenesis inhibitor that has lately been shown as an effective adjuvant therapy in the management of patients with CD. In this article, we review the recent reports on the efficacy and safety of osilodrostat in clinical settings.

MGMT expression in pituitary corticotroph adenomas and its relationship to clinical, pathological, and ultrastructural parameters in patients with Cushing's disease.

INTRODUCTION: Transsphenoidal surgery is the treatment of choice in Cushing's disease (CD), although even late recurrences occur in some patients. Low expression of O-6-methylguanine-DNA methyltransferase (MGMT) has been linked to a high risk of relapse in pituitary tumours, but the evidence for corticotroph adenomas is limited. Therefore, we investigated whether MGMT expression was associated with CD remission or clinicopathological markers of tumour aggressiveness among patients with corticotroph adenomas. MATERIAL AND METHODS: We included 72 consecutive patients (83% female, mean age ±SD: 44.15 ±15.15 years) with CD, who underwent transsphenoidal adenomectomy between 2012 and 2018. The invasiveness of corticotroph tumours was assessed based on the Knosp scale. Immunohistochemistry was used to analyse MGMT expression as well as the proliferation markers (Ki-67, p53, mitotic index). Electron microscopy was used to categorise tumours into densely or sparsely granulated. Early biochemical remission was evaluated in all patients 6 months after pituitary surgery. RESULTS: Early remission was observed in 47 (65%) patients 6 months after surgery. MGMT expression was > 75% in half of all tumours, < 25% in 14 tumours, and 25-50% or 50-75% in 11 tumours. Lower MGMT expression was associated with a larger tumour diameter (p = 0.001), higher adrenocorticotropic hormone (ACTH) concentration (p = 0.002), higher p53 expression (p = 0.026), and higher frequency of sparsely granulated corticotroph adenomas (p = 0.009). Low MGMT expression was significantly related to lower frequency of early clinical remission (p = 0.005). CONCLUSIONS: MGMT predicted the outcomes of transsphenoidal surgery for CD. Pituitary corticotroph adenomas with low MGMT expression may be associated with increased invasiveness and poorer prognosis.