Surrogate threshold effect based on a meta-analysis for the predictive value of progression-free survival for overall survival in hormone receptor-positive, HER2-negative metastatic breast cancer.

Based on the derived STE, it is possible to draw conclusions on a significant effect in OS for a hypothetical trial demonstrating an upper confidence limit of HRPFS < 0.60 in PFS. However, only final OS results are able to confirm if a clinical relevant difference in survival time can be achieved.