Overall survival in the real-world and clinical trials: a case study validating external controls in advanced melanoma.

Aims: We assessed the suitability of real-world data (RWD) as an external control for analysis of overall survival (OS) compared with clinical trial data (CTD) in advanced melanoma. Methods: OS among adults receiving ipilimumab for advanced melanoma was compared between trials (CTD group) and the Flatiron Health database (RWD group) using Cox models. Adjusted analyses accounted for differences in baseline factors; missing data were addressed through multiple imputation. Results: After adjusting for baseline factors and accounting for missingness, OS was similar in the CTD (n = 241) versus RWD groups (n = 816; hazard ratio: 0.98; 95% CI: 0.75-1.26). Conclusion: Flatiron Health data is suitable to construct external control groups for OS in advanced melanoma trials after adjusting for baseline factors and missing data.