Pembrolizumab in Hepatocellular Carcinoma

This is a single-arm Phase II trial of pembrolizumab in patients with hepatitis B virus-related hepatocellular carcinoma with parallel study on baseline and serial change in the immune environment. Subjects should have a confirmed diagnosis of HCC (in accordance with the AASLD guideline) and confirmed chronic infection with hepatitis B virus as defined by positivity for HBsAg. Antiviral therapy for HBV must be given for at least 12 weeks and HBV viral load must be less than 100 IU/mL prior to first dose of study drug. They must have disease not amenable to a curative treatment approach or loco-ablation. Subject must be fit and agreeable with baseline and post-treatment biopsy of tumor. Subjects must have at least one measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, an Eastern Cooperative Oncology Group (ECOG) performance score of 0 or 1 and adequate organ functions. 30 subjects will be enrolled to receive pembrolizumab 200 mg IV every 3 weeks(Q3W). Pre-treatment and on-treatment biopsy after 2 cycles of Pembrolizumab will be preformed. Treatment will be stopped when progression of disease or intolerable toxicity occurs. The primary objectives of this trial are to study the efficacy and safety of pembrolizumab in patients with HBV-related HCC and to study the serial change in RNA expression of immune-related gene panel in post-treatment biopsy tissue. The secondary objectives of this trial are to study the serial change in cytokine profile between pre-treatment and post-treatment samples, to study the PD-L1 immunohistochemical (IHC) expression in tumor sample at baseline and post-treatment tissue samples and to study the presence of tumor infiltrating lymphocytes in the baseline and post-treatment tumor samples. The exploratory objective of this trial is to evaluate the possibility of using baseline and the serial change in RNA expression of immune-related gene panel or PD-L1/2 IHC to predict treatment response.