On April 15, 2025, the U.S. Food and Drug Administration (FDA) approved the expanded use of Isturisa® (osilodrostat) for the treatment of elevated cortisol levels in adults with Cushing’s syndrome, specifically when surgery is not possible or has not fully worked. Isturisa® was originally approved by the FDA in 2020 for the treatment of adult patients with Cushing’s disease, a type of Cushing’s syndrome. Elevated cortisol levels as a result of Cushing’s syndrome can be associated with weight gain, high blood sugar, high blood pressure, and weakened bones. If left untreated, these problems can progress into diabetes, heart issues, and infections. Isturisa® helps to reduce the amount of cortisol the body makes by blocking an enzyme involved in its production.
Safety and efficacy for this expansion was evaluated in the LINC6 trial which enrolled 106 patients in the US, France, and Germany. At 3 months, 71.4% of patients treated with Isturisa® had normal cortisol levels in their urine, 69.2% of patients had normal cortisol levels in their blood, and 50% of patients had normal cortisol levels in their saliva. Common side effects include very low cortisol levels, tiredness, nausea, headache, and swelling of the legs or ankles.