More Gradual Dose Titration Could Reduce Hypocortisolism Risk with Osilodrostat in Cushing's Disease

Maria Fleseriu, MD

Data from a pair of phase 3 studies presented at the American Academy of Clinical Endocrinology’s 30th Annual Meeting (AACE 2021) is providing insight into the effect of dose titration schedules with use of osilodrostat (Isturisa) in patients with Cushing’s disease.

Presented by Maria Fleseriu, MD, of Oregon Health and Science University, the analysis of the LINC3 and LINC4 demonstrated the more gradual titration occurring in LINC4 resulted in a lower proportion of hypocortisolism-related adverse events, suggesting up-titration every 3 weeks rather than every 2 weeks could help lower event risk without compromising mean urinary free cortisol (mUFC) control.

“For patients with Cushing’s disease, osilodrostat should be initiated at the recommended starting dose with incremental dose increases, based on individual response/tolerability aimed at normalizing cortisol levels,” concluded investigators.

With approval from the US Food and Drug Administration in March 2020 for patients not eligible for pituitary surgery or have undergone the surgery but still have the disease, osilodrostat became the first FDA-approved therapy address cortisol overproduction by blocking 11β-hydroxylase. Based on results of LINC3, data from the trial, and the subsequent LINC4 trial, provide the greatest available insight into use of the agent in this patient population.

The study presented at AACE 2021 sought to assess whether slow dose up titration might affect rates of hypocortisolism-related adverse events by comparing titration schedules from both phase 3 trials. Median osilodrostat exposure was 75 (IQR, 48-117) weeks and 70 (IQR, 49-87) weeks in LINC3 and LINC4, respectively. The median time to first mUFC equal to or less than ULN was 41 (IQR, 30-42) days in LINC3 and 35 (IQR, 34-52) days in LINC4.

Adverse events potentially related to hypocortisolism were more common among patients in LINC3 (51%, n=70) than LINC4 (27%, n=20). Upon analysis of adverse events, investigators found the most commonly reported type of adverse event was adrenal insufficiency, which included events of glucocorticoid deficiency, adrenocortical insufficiency, steroid withdrawal syndrome, and decreased urinary free cortisol.

Results incited the majority of hypocortisolism-related adverse events occurred during the dos titration periods of each trial. In LINC3, 54 of the 70 (77%) hypocortisolism-related adverse events occurred by week 26. In comparison, 58% of hypocortisolism-related adverse events occurring in LINC4 occurred prior to week 12. Investigators noted most of events that occurred were mild or moderate and managed with dose interruption or reduction of osilodrostat or concomitant medications.

This study, “Effect of Dosing and Titration of Osilodrostat on Efficacy and Safety in Patients with Cushing's Disease (CD): Results from Two Phase III Trials (LINC3 and LINC4),” was presented at AACE 2021.