Proper dose titration makes a difference
Adverse events occurred in 26 of the 50 patients (52%) who received any treatment; 1 patient had a serious adverse event, 7 patients required a dosage adjustment because of adverse events, and 6 patients stopped treatment. The most common adverse events were gastrointestinal – nausea in 24% and decreased appetite in 18% – as well as mild symptoms consistent with adrenal insufficiency such as fatigue and headache. Six patients (12%) were identified with reversible adrenal insufficiency, and no patients complained of worsening acne or hirsutism.
“I think the adverse events are a function of [less than optimal] dose titration and variability in UFC levels,” said Dr. Nieman.
This test of metyrapone’s efficacy comes a year after the FDA approved osilodrostat (Isturisa) for treating Cushing’s disease (but not Cushing’s syndrome). Like metyrapone, osilodrostat controls cortisol overproduction by blocking the enzyme 11-beta-hydroxylase and preventing cortisol synthesis, and osilodrostat was the first agent with these properties to receive an FDA label for therapy.
Osilodrostat “is the only adrenal steroidogenesis inhibitor assessed in randomized controlled long-term trials – over 200 patients with Cushing’s disease – and it has been shown to be highly effective at maintaining normal urinary free cortisol in large majority of patients with Cushing’s disease, as well as Cushing’s syndrome in a study in Japan. Adrenal insufficiency was high [with osilodrostat], especially with the high dose in the trial with forced uptitration. In my clinical practice I have noticed less adrenal insufficiency, but I use much slower drug titration,” said Dr. Fleseriu.
“I think these drugs [metyrapone and osilodrostat] are relatively equivalent,” Dr. Nieman said during discussion of her report. “One nonmedical judgment will be cost,” she added. “Everyone is looking forward to what the pricing structure will be for the new drugs.”
Dr. Fleseriu noted that “for most patients, surgery is first-line therapy, and rarely medication is an alternative first option, especially for Cushing’s disease. However, medical therapy is essential in the management of patients with Cushing’s syndrome when curative surgery fails, surgery is not feasible, when a patient is awaiting radiation’s effect, and for recurrent cases of Cushing’s syndrome.”
PROMPT was sponsored by HRA Pharma, the company that markets metyrapone. Dr. Nieman had no disclosures, but several of her associates on the study are HRA employees. Dr. Fleseriu has been a consultant to Novartis, Recordati, Sparrow, and Strongbridge.