Serum PD-1 Levels Change with Immunotherapy Response but Do Not Predict Prognosis in Patients with Hepatocellular Carcinoma

Background/Aims: Programmed death receptor 1 (PD-1) is a promising new target for treatment of patients with hepatocellular carcinoma (HCC). A high expression level of programmed death-ligand 1 (PD-L1) is a possible prognostic indicator for poor outcome in other malignancies. Here, we investigated the clinical significance of PD-1 and PD-L1 in patients with HCC. Methods: We enrolled patients with HCC who underwent surgical resection at Severance Hospital between 2012 and 2017 and investigated the levels of PD-L1 in HCC tissues (tPD-L1) and PD-L1/PD-1 in serum (sPD-L1/sPD-1). We also aimed to determine whether expression levels correlated with clinical and histological features. Results: A total of 72 patient samples were analyzed. The median sPD-L1 and sPD-1 levels were 25.72 and 341.44 pg/mL, respectively. A positive correlation was detected between tPD-L1 and sPD-1 levels (R2=0.426, P 50% reduction in sPD-1 levels was observed immediately after nivolumab administration. However, sPD-1 level was not associated directly with prognosis in patients with advanced HCC. Conclusions: The results demonstrated that PD-L1 and PD-1 levels changed according to the immunotherapy. However, no significant association with clinical outcome in patients with HCC was detected. (J Liver Cancer 2019;19:108-116)