The feasibility of personalized and tumor-informed ctDNA assay for early recurrence detection in post-liver transplantation patients with hepatocellular carcinoma.

e16283 Background: Hepatocellular carcinoma (HCC) has a high likelihood of relapse following standard-of-care (SOC) resection or liver transplantation (LT). This study explored the role of circulating tumor DNA (ctDNA) in predicting relapse or progression in HCC patients. Methods: We conducted a real-world analysis of ctDNA data from 125 HCC patients (721 plasma samples) undergoing curative-intent treatment. The cohort was divided into four subgroups: Cohort A (N = 64) and Cohort B (N = 52) included patients under recurrence surveillance post-LT or resection, respectively. Cohort C (N = 4) and Cohort D (N = 5) involved patients monitored for treatment response, with known recurrence or inoperable disease, respectively. All patients received SOC management, including AFP testing. A personalized, tumor-informed 16-plex PCR-NGS assay (SignateraTM, Natera, Inc.) was employed for ctDNA analysis. The molecular residual disease (MRD) period was defined as 2-12 weeks post-LT or resection (Cohorts A and B) before initiating adjuvant therapy (AT). The surveillance period was designated as after the MRD window or 2 weeks post-AT (Cohort B), or during ongoing treatment (Cohorts C and D). Results: The cohort had a median follow-up of 40 months (range: 1.5 - 60). In Cohort A, 97.2% (35/36) of patients with negative ctDNA during the MRD window remained negative in subsequent surveillance. In Cohort B, ctDNA was detected in 29.4% (10/34) of patients during the MRD window, all of whom experienced clinical recurrence (HR: 7.2, 95% CI: 2.6-20, p < 0.0001). During the surveillance phase, ctDNA was detected in 32.3% (10/31) of patients, all of whom relapsed (HR: 18.0, 95% CI: 3.9-85, p < 0.0001). In Cohorts C and D, on-treatment ctDNA trends aligned with imaging-based treatment response assessments. Compared to AFP, ctDNA demonstrated greater sensitivity and significantly longer lead times for detecting recurrence (7.9 months vs. 2.2 months). Conclusions: Serial ctDNA monitoring effectively identified early HCC recurrence post-resection and LT. Additionally, ctDNA proved valuable in monitoring treatment responses and clarifying uncertain imaging results.