Supplementary Material for: Circulating Cell-Free DNA as a Biomarker for Prognosis and Response to Systemic Therapy in Patients with Unresectable Hepatocellular Carcinoma

Introduction: Systemic therapy provides clinical benefits to a subset of patients with advanced unresectable hepatocellular carcinoma (HCC). However, few biomarkers are available for predicting prognosis and treatment response in patients with advanced HCC undergoing treatment with systemic therapies. This study aimed to examine whether circulating cell-free DNA (cfDNA) containing circulating tumor DNA can act as a therapeutic response and prognostic biomarker in patients with advanced HCC. Methods: We analyzed longitudinally collected plasma cfDNA of patients with advanced HCC who were naïve to systemic therapy, and assessed their prognostic and predictive values to determine treatment responses. Results: cfDNA concentration positively correlated with entire tumor volume on computed tomography before (P = 0.0231) and at the end (P < 0.0001) of the first-line systemic therapy. The overall survival rate was higher in patients with cfDNA concentrations lower than the median cfDNA level at baseline compared to patients with higher cfDNA concentrations (hazard ratio, 0.2765; 95% confidence interval, 0.08–0.81; P = 0.0197). The ratio of cfDNA at four weeks to that at baseline was predictive of radiographic disease response. In patients with progressive disease, cfDNA concentration at four weeks increased significantly (P = 0.0245), whereas the concentration remained unchanged in patients with other disease courses (P = 0.9375). Conclusion: The baseline plasma cfDNA concentration can be used as a prognostic biomarker in patients with advanced HCC. cfDNA kinetics may also predict the tumor response to therapy and disease progression.