Overall response rate (ORR) and progression-free survival (PFS) are commonly used as endpoints for phase II trials. However, the ultimate goal is to bring survival benefit for the patients. We aimed to assess the correlation between ORR, median PFS and overall survival (OS) using aggregated data from a systematic review of second-line systemic therapies in advanced biliary tract cancer (BTC) patients.

Clinical trials were identified using Medline database. Studies only enrolling patients with gallbladder cancer were not included. Searches were last updated on April 2020. Eligible studies reported OS, PFS and/or ORR data for BTC patients receiving second-line systemic chemotherapy. Pearson weighted correlation was estimated between OS and ORR and between median OS and PFS.

Seventeen studies (N = 912 patients) were selected. There was a strong correlation between median OS/ORR in the overall analysis (r = 0.85; P < 0.0001), both for trials with chemotherapy (r = 0.90; P=0.0152) and targeted therapy (r = 0.84; P = 0.0006). In contrast, the correlation between median OS/PFS, albeit significant in the overall analysis (r = 0.80; P < 0.0001), remained significant only for targeted therapies in the sensitivity analysis (r = 0.83; P = 0.0009).

ORR seems to be a more interesting intermediate endpoint in BTC in second line for both chemotherapy and targeted therapies, while PFS may be relevant only for targeted therapy trials. Further well-designed studies for surrogacy evaluation should be performed to confirm this observation.