Progression‐free survival is a weakly predictive surrogate end‐point for overall survival in follicular lymphoma: A systematic review and meta‐analysis

Although progression-free survival (PFS) is a commonly used surrogate end-point for clinical trials of follicular lymphoma (FL), no analyses have evaluated the strength of surrogacy for PFS with overall survival (OS). A systematic review was performed and 20 studies (total participants, 10 724) met final inclusion criteria. PFS was weakly associated with OS (correlation coefficient; 0.383, p < 0.001). The coefficient of determination was 0.15 (95% CI: 0.002-0.35) suggesting 15% of OS variance could be explained by changes in PFS. This challenges the role for PFS as a surrogate end-point for clinical trials and drug approvals.