The following article features coverage from the American Society of Clinical Oncology 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Chinese researchers demonstrated that circulating tumor DNA (ctDNA) is an emerging biomarker that could help monitor treatment response and disease progression in patients with hepatocellular carcinoma (HCC).

According to a poster presented by Chih-Hung Hsu, of National Taiwan University Cancer Center, and colleagues, the use of ctDNA has not yet been established as a method of noninvasive monitoring for patients with HCC.

Hsu and colleagues looked at a subset of 48 patients with HCC in a phase 1b study testing atezolizumab plus bevacizumab. In order to represent various response categories, of the included patients 10 had a complete response, 11 had a partial response, 12 had stable disease, and 15 had progressive disease.

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To study ctDNA, serial plasma samples were collected. The researchers used a personalized ctDNA assay (SIGNATERA 16-ples multiplex PCR next-generation sequencing assay) specific to each patient’s tumor mutational signatures.

ctDNA was detected in the majority of patients (96%) and showed sensitivity in the majority of patients (96%). There was a median of 70.6 mean tumor molecules per mL of plasma and a median of 1.8% mean variant allele frequency in plasma.

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The researchers found that higher levels of ctDNA detected at cycle 1 day 1 were associated with an increased tumor burden (P <.03). Additionally, dynamic changes in ctDNA post-treatment were associated with response at cycle 4 day 1.

A longer progression-free survival was found in patients with ctDNA that became undetectable post-treatment. Median progression-free survival in those with ctDNA present was 6.5 months compared with not reached in those with cleared ctDNA (hazard ratio, 12; P <.00029).

Read more of Cancer Therapy Advisor‘s coverage of the ASCO 2021 meeting by visiting the conference page.


Hsu CH, Lu S, Abbas A, et al. Longitudinal and personalized detection of circulating tumor DNA (CTDNA) for monitoring efficacy of atezolizumab plus bevacizumab in patients with unresectable hepatocellular carcinoma (HCC). Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr 3531.