A Block-and-Replace Therapy With Osilodrostat and Concomitant Glucocorticoid Replacement

The major goal of this study is to determine the incidence of adrenal insufficiency in patients with endogenous Cushing syndrome receiving osilodrostat treatment combined with a replacement of glucocorticoid (block-and-replace approach). The investigators are also evaluating new biomarker steroids to reflect adequate osilodrostat dosing, the durability and safety, and clinical improvement during treatment.

Inclusion Criteria: * Endogenous Cushing syndrome, either following surgery or not candidates for surgery * Under consideration to receive osilodrostat as part of their clinical care * Able to provide informed consent. Exclusion Criteria: * Treatment with other investigational drugs within 30 days or five half-lives (whichever is longer). * A history of hypersensitivity to osilodrostat or therapies of a similar chemical class.