Osilodrostat treatment was found to be associated with a rapid and sustained reduction in mean concentration of urinary free cortisol (UFC) and improved clinical symptoms in patients with Cushing’s disease, according to the results of a prospective, multicenter, open-label, phase 3 study published in the Lancet Diabetes Endocrinology.
Osilodrostat is an oral inhibitor of 11-β hydroxylase cytochrome P450. Adults aged 18 to 75 years of age with diagnosed persistent or recurrent Cushing’s disease were recruited between 2014 and 2017 at 66 hospitals in 19 countries. Cushing’s disease was defined by a mean UFC concentration over a 24-hour period >1.5 times greater than the upper limit of normal (ULN) and morning plasma adrenocorticotropic hormone level above normal limits.
Participants (n=137) received 30 mg osilodrostat twice daily, dose which was adjusted every 2 weeks until week 12 on the basis of mean 24-hourUFC concentration. The determined maintenance dose was continued until week 24. At week 26, participants who had achieved 24-hour UFC concentration ≤ ULN and did not need titration after week 12 were randomly assigned in an equal ratio to maintain osilodrostat treatment or were switched to a placebo for 8 weeks. This 8-week period of the study was double-blinded. During weeks 35 to 48, all patients were returned to osilodrostat treatment.
In this cohort, mean age was 40.0 years (range, 19.0-70.0 years), 77% of participants were women, the average time since diagnosis was 47.2 months (interquartile range [IQR], 19.0-88.3), 88% had previous pituitary surgery, 16% had pituitary radiation therapy, and 74% had medicinal therapy. At baseline, the mean 24-hour UFC concentration was 1006±1590 nmol/24 h.
At week 24, 53% of participants achieved a mean 24-hour UFC concentration ≤ULN without increases in dose after week 12 and were eligible for randomization (osilodrostat, n=36; placebo, n=35). At week 34, more patients receiving osilodrostat vs placebo maintained a complete response (86% vs 29%, respectively; odds ratio [OR], 13.7; 95% CI, 3.7-53.4; P <.0001).
Improvements in cardiovascular-related metabolic parameters associated with hypercortisolism and overall measures of well-being were observed. Levels of high-density lipoprotein decreased by week 48 (-0.3 mmol/L; 95% CI, .0.3 to -0.2), mean Cushing’s quality of life score increased by 52.4% (95% CI, 32.3-72.7), and Beck Depression Inventory score decreased by 31.8% (95% CI, -44.3 to -19.3).
Adverse events were hypocortisolism (51%), adverse events related with adrenal hormone precursors (42%), nausea (42%), headache (34%), fatigue (28%), and adrenal insufficiency (28%). A total of 18% of participants dropped out of the study due to adverse events.
The major limitation of this study was the short withdrawal period (8 weeks) which may not have permitted to observe symptoms of hypercortisolism.
“Alongside careful dose adjustments and monitoring of known risks associated with osilodrostat, our findings indicate a positive benefit– risk consideration of treatment for most patients with Cushing’s disease,” concluded the study authors.
Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.
Pivonello R, Fleseriu M, Newell-Price J, et al. Efficacy and safety of osilodrostat in patients with Cushing’s disease (LINC 3): a multicentre phase III study with a doubleblind, randomised withdrawal phase. Lancet Diabetes Endocrinol. 2020;S2213-8587(20)30240-0. doi:10.1016/S2213-8587(29)30240-0