Des-gamma-carboxy prothrombin (DCP) as a biomarker for treatment response in hepatocellular carcinoma.

Abstract

547 Background: Causes of variable disease response to first-line treatment with atezolizumab/bevacizumab (atezo/bev) in hepatocellular carcinoma (HCC) patients remain unclear. Identifying tumor markers that predict treatment efficacy may help raise clinical suspicion for early disease progression. The role of des-gamma-carboxy prothrombin (DCP) is not well established in Hepatitis B Virus (HBV) non-endemic areas. This study aimed to investigate DCP as a predictive biomarker of atezo/bev treatment response in HCC patients. Methods: This single-center retrospective analysis evaluated DCP and radiographic response in HCC patients who received atezo/bev in the first-line setting. DCP was measured at the time of best response evaluation and compared to day one of atezo/bev initiation. Elevated DCP was defined by >=7.5 ng/mL. DCP response was defined as a decrease of >=50% at response assessment compared with baseline. Treatment response was evaluated based on imaging modalities including computed tomography and/or magnetic resonance imaging. Objective response rate (ORR) was defined as the percentage of patients with complete response (CR) and partial response (PR). Disease control rate (DCR) was defined as the percentage of patients with CR, PR, and stable disease (SD). No Response (NR) was defined as the percentage of patients with SD and PD. Comparisons of treatment effects were performed using two-tailed Fisher Exact Probability Test. Results: A total of 53 HCC patients treated with atezo/bev as first-line therapy were included. The best treatment responses according to radiographic evaluation were as follows: CR 3.8%, PR 22.6%, SD 52.8%, and PD 20.8%, respectively. Patients with DCP response had ORR of 69% (odds ratio, 15.75; 95% CI, 3.50-70.9; P=.0002) and DCR of 100% ( P=.047). Patients with >=50% increase in DCP at response evaluation compared to day one of treatment had ORR of 4.5% and NR of 95% ( P=.0035). On day one of treatment, 70% of patients had an elevated DCP. There was no difference between elevated DCP vs non-elevated DCP on day one of treatment and ORR. Conclusions: This study found that DCP has utility in predicting response to atezo/bev for HCC patients in HBV non-endemic areas. Further studies are needed to confirm findings and evaluate the prognostic implications of DCP in HBV non-endemic areas.