Inclusion Criteria:

1. Adult male or female, aged 18 years or more
2. Evidence of chronic 'active' ACTH-dependent Cushing's syndrome
3. Evidence of acutely 'active' ACTH-dependent Cushing's syndrome within 10 days of Day 1
4. Participants with documented ACTH-dependent Cushing's syndrome taking short-acting steroidogenesis inhibitors (ketoconazole, levoketoconazole, osilodrostat, or metyrapone) may participate after a washout period of at least 5 days, if they meet other study inclusion criteria, relative to Investigator's judgment. Participants with documented ACTH-dependent Cushing's syndrome taking cabergoline may participate after a washout period of at least 14 days, if they meet other study inclusion criteria

Exclusion Criteria:

1. Women who are pregnant or lactating
2. History of bilateral adrenalectomy
3. Previous pituitary MRI findings of a putative ACTH-secreting lesion within 3 mm of the optic chiasm
4. Presence of any known malignancy
5. Use of mitotane
6. Previous unsuccessful surgery for Cushing's syndrome within 6 weeks