Methylated SEPT9 assay-based liquid biopsy as a biomarker in molecular targeted agent-treated hepatocellular carcinoma

Background The development of molecular targeted agents (MTAs) has changed the treatment strategy for hepatocellular carcinoma (HCC). However, currently, there are no established predictive biomarkers for the treatment efficacy of MTAs. Previously, we developed a novel liquid biopsy test for HCC screening using sensitive methylated DNA testing of septin 9 gene ( SEPT9 ). Here, we hypothesized that SEPT9 could be used as a biomarker for MTA treatment efficacy. Methods We enrolled 157 patients receiving sorafenib or lenvatinib as a first-line therapy and allocated 85 and 72 patients to the training and validation cohorts, respectively. For the methylation assay, DNA was treated with methylation-sensitive restriction enzymes, followed by multiplex droplet digital PCR. Various clinical parameters were compared with clinical outcomes. Results The multivariate analysis revealed Eastern Cooperative Oncology Group performance status (≥ 1; p = 0.048), alpha-fetoprotein (AFP) (≥ 400 ng/mL; p < 0.001), and methylated-septin-9 (m- SEPT9 ) (≥ 205 copies/mL; p = 0.018) as significant predictors of poor overall survival (OS) in the training cohort. m- SEPT 9 was identified as a predictor of poor OS in the validation cohort. We developed a predictive score, called the MTA score, consisting of these three significant OS parameters (two points were added for AFP and one point for each of the other predictors). Patients with MTA scores ≥ 2 showed a significantly poor prognosis compared to those with MTA scores ≤ 1 in both the training and validation cohorts. Conclusions m- SEPT9 could be a potential predictive biomarker for survival in patients with HCC treated with MTAs. Graphical abstract