The value of pretreatment 18F-FDG PET/CT to predict the pathological treatment response of hepatocellular carcinoma patients treated with PD-1 inhibitors and lenvatinib as a conversion therapy in BCLC stage C.

Abstract

e16130 Background: Current systemic therapy for patients with hepatocellular carcinoma (HCC) in BCLC stage C consists of tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs). This study aimed to assess the parameters of pretreatment 18F-FDG PET/CT as a predictor of the pathological treatment response (PTR) of HCC patients treated with PD-1 inhibitors and lenvatinib as a conversion therapy in BCLC stage C. Methods: We retrospective analyzed 20 consecutive patients with HCC in BCLC stage C. All patients underwent pretreatment 18F-FDG PET/CT and treated with PD-1 inhibitors and lenvatinib as a conversion therapy and surgery. Patients were categorized into responders (n=9) and non-responders (n=11) according to PTR. The PTR was classified based on the primary tumor cellularity (responder, defined as <10% cellularity). The parameters of PET/CT including lesion size, SUVmax (max standardized uptake value), SUVmean (mean standard uptake value), MTV2.5 (metabolic tumor volume2.5), TLG2.5 (total lesion glycolysis2.5), SUVpeak (peak standard uptake value), and TLR (tumor-to-normal liver standardized uptake value ratio, SUVmax of the tumor/SUVmean of the normal liver parenchyma) were calculated and compared between two groups. The diagnostic efficacy was evaluated by ROC. PTR was compared with pretreatment 18F-FDG PET/CT parameters by using Spearman correlation analysis. The prognosis was followed up. Results: TLR (5.59±1.90 vs. 2.84±1.70, respectively; P=0.003) showed significant difference in responders and non-responders and the largest area under the curve (sensitivity: 1.000, specificity: 0.727, positive predictive value: 0.750, negative predictive value: 1.000, AUC=0.899, 95%CI: 0.759-1.000), and optimal diagnostic threshold of 3.09. The relationship between 18F-FDG PET/CT parameters and PTR showed TLR had moderate positive correlation with pathological treatment response, with correlation coefficients (rs) of 0.69 ( P＜0.05). During the follow-up, no patients died, and 1 patient (11.1%) showed tumor recurrence in responders. In all 11 non-responders, 5 patients (45.5%) had tumor recurrence and 4 patients (36.4%) died. Conclusions: The TLR may be a powerful marker to predict the PTR of HCC patients with BCLC stage C who treated with PD-1 inhibitors and lenvatinib as a conversion therapy.[Table: see text]