Regulatory correspondence and reporting show the FDA raised substantive concerns about Corcept Therapeutics’ lead submission for a Cushing’s syndrome drug before the company filed its application. The agency warned Corcept that the filing could encounter significant review issues, and the company’s subsequent rejection aligns with those prior communications. The FDA’s released complete response letter and agency statements indicate regulators had signaled issues early in review discussions; Corcept has defended its submission pathway but must now address the deficiencies outlined. The exchange highlights the importance of resolving substantial regulatory questions pre‑submission to avoid protracted review cycles. For sponsors, the episode underscores heightened agency expectations around data integrity and submission readiness in endocrine and rare disease programs, and it stresses the consequences of proceeding to file without clear regulatory alignment.