Methylated ctDNA Quantification: Non-Invasive Approach to Monitoring Hepatocellular Carcinoma Burden

Abstract

Background: Non-invasive, precision monitoring of hepatocellular carcinoma (HCC) treatment efficacy would greatly facilitate personalized therapy and improve patient outcomes. We hypothesize that quantifying methylated circulating tumor DNA (ctDNA) can be used to effectively monitor HCC burden without the need for biopsy. Study Design: Blood samples were collected from 25 patients, 21 with HCC and 4 with benign liver masses, at various timepoints throughout the course of treatment at a high-volume academic medical center. Quantification of methylated ctDNA molecules assessed CpG sites on over 550 preselected cancer-specific amplicons. The Tumor Methylation Score (TMS) was calculated by measuring the difference between the amount of methylation in the plasma and buffy coat with a normal cutoff of ≤ 120. Results: Among 10 surgical HCC patients (5 surgical resections and 5 liver transplants), TMS revealed a statistically significant, rapid postoperative decline in 9. One patient who had a persistently elevated TMS on POD1 was subsequently found to have had metastatic disease. Patients in the negative control cohort all had normal-range pre- and post-operative TMS. Pre-operative TMS correlated moderately with tumor burden on pathology (Spearman r=0.54) of surgical specimens. From 11 subjects undergoing systemic therapy or Y90 radioembolization, analysis of 16 time periods demonstrated that the change in TMS (ΔTMS) was better associated with tumor progression than the change in AFP (ΔAFP) [area under the curve (AUC) 0.800 and 0.783, respectively]. A composite score combining ΔTMS and ΔAFP further improved performance for detecting tumor progression with an AUC of 0.892. Conclusions: These findings indicate that ctDNA methylation scores can effectively evaluate changes in tumor burden without the need for tumor biopsy.