Osilodrostat normalizes urinary free cortisol in most adults with Cushing’s disease
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More than three-quarters of adults with Cushing’s disease assigned osilodrostat had a normalized mean urinary free cortisol level at 12 weeks and maintained a normal level at 36 weeks, according to data from the LINC 4 phase 3 trial.
In findings published in The Journal of Clinical Endocrinology & Metabolism, 77% of adults with Cushing’s disease randomly assigned to osilodrostat (Isturisa, Recordati) had mean urinary free cortisol (UFC) levels reduced to below the upper limit of normal at 12 weeks compared with 8% of adults assigned to placebo.
“Osilodrostat is a highly effective treatment for Cushing’s disease, normalizing urinary free cortisol excretion in 77% of patients after 12 weeks’ treatment,” Mônica Gadelha, MD, professor of endocrinology at The Federal University of Rio de Janeiro, and colleagues wrote. “Cortisol reductions were maintained throughout 48 weeks of treatment and were accompanied by improvements in clinical signs of hypercortisolism and quality of life.”
Gadelha and colleagues enrolled 73 adults aged 18 to 75 years with Cushing’s disease from 40 centers in 14 countries into the LINC 4 phase 3 trial. Participants were randomly assigned to 2 mg osilodrostat twice daily (n = 48) or placebo (n = 25) for 12 weeks. Urinary samples were collected at weeks 2, 5 and 8 to measure mean UFC, and dosage was adjusted based on efficacy and tolerability. After 12 weeks, participants from both groups received osilodrostat in a 36-week open-label treatment period. All participants restarted the open-label portion of the trial at 2 mg osilodrostat unless they were on a lower dose at week 12. Dose adjustments in the open-label phase were made using the same guidelines in the randomized, double-blind, placebo-controlled trial. The primary endpoint was the efficacy of osilodrostat at achieving a mean UFC below the upper limit of normal of 138 nmol per 24 hours at 12 weeks vs. placebo; the key secondary endpoint was the percentage of participants achieving a normal mean UFC at 36 weeks.
At 12 weeks, the percentage of adults with a normalized mean UFC level was higher in the osilodrostat group compared with placebo (77.1% vs. 8%; P < .0001).
At 36 weeks, 80.8% of all participants had a normal mean UFC level. The overall response rate was 79.5% at 48 weeks.
Median time to first controlled mean UFC response was 35 days for those randomly assigned to osilodrostat as well as those randomly assigned to placebo who crossed over to osilodrostat for the open-label phase. At 48 weeks, 84% of participants were receiving 10 mg or less of osilodrostat per day, including 56% receiving 4 mg or less daily.
At 12 weeks, the osilodrostat group had several cardiovascular and metabolic-related improvements, including systolic and diastolic blood pressure, HbA1c, HDL cholesterol, body weight and waist circumference. No changes were observed in the placebo group.
“The improvements in cardiovascular and metabolic parameters were sustained throughout osilodrostat treatment and have the potential to alleviate the burden of comorbidities in many patients with Cushing’s disease,” the researchers wrote.
At 12 weeks, 52.5% of those receiving osilodrostat had a reduction in supraclavicular fat pad and 50% had a reduction in dorsal fat pad. At least 25% of participants also had improvements in facial redness, striae, proximal muscle atrophy and central obesity. Improvements were sustained through week 48.
During the placebo-controlled trial, grade 3 and 4 adverse events occurred for about 20% of participants in both groups. For the entire study, 38.4% of adults reported grade 3 and 4 adverse events, with the most common being hypertension. Eight participants discontinued the study due to adverse events.
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