Programmed Death Ligand 1 Expression as a Prognostic Marker in Patients with Advanced Biliary Tract Cancer

Abstract

Background: Biliary tract cancer (BTC) is associated with poor prognosis because of its aggressive and heterogeneous nature. Programmed death ligand 1 (PD-L1) has been considered a novel biomarker for prognosis and response of immune checkpoint inhibitors in various tumors. However, there are limited data reporting on the role of PD-L1 in advanced BTC patients. Patients and Methods: We analyzed 186 patients with advanced BTC who received palliative gemcitabine and platinum between May 2010 and December 2019. All patients were evaluated for PD-L1 expression by combined positive score positivity. Results: Of the 186 patients, the primary tumor location was intrahepatic cholangiocarcinoma (IHCC) in 72 (38.7%), extrahepatic cholangiocarcinoma (EHCC) in 90 (48.4%), and gallbladder (GB) cancer in 24 (12.9%). Among all the patients, 53 (28.5%) had PD-L1 positivity. The median overall survival (OS) of patients with PD-L1 positivity or negativity was 12.1 and 15.4 months, respectively. The median progression-free survival (PFS) in patients with PD-L1 positivity or negativity was 5.7 and 7.1 months, respectively. OS and PFS were not statistically different between groups. In subgroup analysis, EHCC patients with PD-L1 negativity had more favorable OS (17.2 vs. 11.6 months, p = 0.002) and PFS (7.8 vs. 5.4 months, p = 0.005) than those who were PD-L1-positive. However, this finding was not reproduced in patients with IHCC or GB cancer. Conclusion: This study demonstrated that PD-L1 expression might be a novel prognostic biomarker in patients with EHCC but not in patients with IHCC or GB cancer.