SPI-62 as a Treatment for Adrenocorticotropic Hormone-dependent Cushing's Syndrome

Inclusion Criteria: * Male or non-menstruating female * 18 years or older * Active and consistent cortisol excess * Documented diagnosis of ACTH-dependent Cushing's syndrome including Cushing's disease, ectopic ACTH secretion, and ectopic CRH secretion. Exclusion Criteria: * Recent (within 6 weeks) surgery for Cushing's or surgery planned within 24 weeks of randomization. * History of any fractionated radiation therapy for Cushing's within the past 2 years or conventional radiation therapy within 4 years. * History of bilateral adrenalectomy or exogenous, pseudo, cyclic, or non-ACTH-dependent Cushing's syndrome (including certain inherited conditions). * High risk of acute morbidity from corticotroph adenoma growth (similar to that which occurs with Nelson's syndrome) defined as current evidence of macroadenoma at risk of impingement of vital structures. * Any current or prior medical condition, medical or surgical therapies, or clinical trial participation expected to interfere with the conduct of the study or the evaluation of its results, including but not limited to poor venous access or recent receipt or donation of blood products. * Women who are currently pregnant, lactating or planning fertility and unwilling to adhere to approved contraceptives or abstinence.