RecruitingDrug trialA Block-and-Replace Therapy With Osilodrostat and Concomitant Glucocorticoid ReplacementThe 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.