Matching-Adjusted Indirect Comparison of Osilodrostat Versus Metyrapone for the Treatment of Cushing's Syndrome

Introduction: Cushing’s syndrome (CS) is a rare, chronic condition caused by prolonged exposure to elevated levels of circulating cortisol, and characterized by high morbidity and mortality. The primary treatment option for CS is surgery; however, medical therapy may be useful when surgery is unsuitable, refused, or has not been curative, or a rapid control of hypercortisolism is required. While osilodrostat and metyrapone are two treatments for controlling cortisol levels, they have not been compared directly in a clinical trial. This study evaluated the comparative efficacy and tolerability of osilodrostat versus metyrapone for the treatment of CS using indirect treatment comparison methods. Methods: Unanchored matching-adjusted indirect comparison was used to synthesize relative treatment effects by reweighting patient-level data from two clinical trials for osilodrostat to published aggregate data for metyrapone. Efficacy endpoints included complete response (CR), defined as mean urinary free cortisol ≤ 1.0 × the upper limit of normal, at Weeks 12, 24, and 36. Tolerability endpoints included all-cause treatment discontinuation and treatment discontinuation due to lack of efficacy (LoE) or adverse events (AEs). Results: The base case analysis demonstrated that osilodrostat provides increased odds of CR versus metyrapone at Week 12 [odds ratio (OR) 2.75; 95% confidence interval (CI) 1.29, 5.88], Week 24 (OR 3.28; 95% CI 1.58, 6.84) and Week 36 (OR 10.50; 95% CI 1.84, 59.96), implying a greater proportion of patients experience normalized cortisol levels at these time-points. Although the base case analysis showed that the odds of all-cause discontinuation and discontinuation due to LoE or AEs were numerically lower for osilodrostat, the evidence was insufficient to show a statistically significant difference. Conclusion: These analyses show that osilodrostat increases the odds of achieving CR at Weeks 12, 24, and 36 versus metyrapone, demonstrating that osilodrostat is a more efficacious treatment option for normalizing cortisol levels in CS patients.