Progression-free survival as a potential surrogate endpoint for overall survival after conversion therapy for...

Whether progression-free survival (PFS) is a valid surrogate endpoint for overall survival (OS) in patients who underwent conversion therapy for hepatocellular carcinoma (HCC) remains uncertain. The present study compares the two survival measures in this patient cohort. Data on unresectable HCC patients undergoing conversion therapy from 20 Chinese medical centers (2019-2023) were retrieved. The correlation (ρ) between PFS and OS was assessed using the rank correlation method combined with iterative multiple imputation to account for censoring. As a secondary analysis, the correlation was evaluated according to the conversion regimen and treatment response. The pairwise correlation between PFS and OS was calculated through sensitivity analysis. A total of 1909 patients with unresectable HCC were included. A moderately strong correlation was found between PFS and OS (ρ = 0.74, 95%CI 0.72-0.76). The strength of the correlation was similar regardless of the conversion therapy regimen (interventional therapy plus systemic therapy: ρ = 0.75, 0.72-0.77; systemic therapy alone: ρ = 0.73, 0.57-0.83; interventional therapy alone: ρ = 0.74, 0.70-0.78). The mean (standard deviation) pairwise correlation coefficient between 24-month PFS and 48-month OS was 0.74 (0.08). Those who responded completely (hazard ratio = 0.24, 95%CI 0.21-0.28) or partially (hazard ratio = 0.23, 95%CI 0.20-0.25) to conversion therapy showed significantly better PFS than those who did not. In patients with unresectable HCC undergoing conversion therapy, a moderately strong correlation was observed between PFS and OS, and this correlation was unaffected by the conversion therapy regimen. Better tumor response following conversion therapy could be used to identify patients with improved PFS.