SAT501 A lncRNA-associated ceRNA regulatory network in MVI positive hepatocellular carcinoma influences their sensitivity to sorafenib Zhiwen Luo 1 , Xinyu Bi 2 . 1 National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Department of Hepatobiliary Surgery, Beijing, China; 2 National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Department of Hepatobiliary Surgery, beijing, China Email: beexy1971@163.com Background and Aims: Microvascular invasion (MVI) is a histological feature of hepatocellular carcinoma (HCC) related to aggressiveness. But different sensitivity to first line targeted drug, sorafenib, in MVI + HCC has been observed. Long noncoding RNAs (lncRNAs) can act as microRNA (miRNA) sponges to regulate protein-coding gene expres- sion; so lncRNAs are considered as a major part of competitive endogenous RNA (ceRNA) network and have attracted growing attention. We explored the regulatory mechanisms and functional roles of lncRNAs as ceRNAs in MVI + HCC, and ceRNA network’s potential impact on prognosis and sensitivity to sorafenib in MVI + HCC patient. Method: We studied the expression profiles, prognostic value of lncRNA, miRNA, and mRNA from MVI + HCC patients, established a prognosis-related network of dysregulated ceRNAs and analyzed its role in sensitivity to sorafenib and radiomics features by bioinfor- matics methods. Results: A ceRNA network including 13 lncRNAs, 3 miRNAs, and 2 mRNAs specific to MVI+ HCC was established. 6 lncRNAs (ARHGEF7- AS1, ATP2B2-IT1, LINC00330, MUC2, TLR8-AS1 and ZNF385D-AS1), 2 miRNAs (has-mir-206 and has-mir-373) and two mRNAs (PAX3, SIK1) were prognostic biomarkers for MVI + HCC. PAX3 was an unfavorable prognostic gene (HR = 1.9, 95%CI 1.01 ∼ 3.60), while SIK1 favored the prognosis (HR = 0.4, 95%CI 0.19 ∼ 0.85). PAX3 as a stratification in recurrence predicting model was used to identify MVI + HCC with high or low recurrence risk. Datamining into the dataset of phase 3 STORM trial showed no difference in the influence of PAX3 level on the outcome between sorafenib HCC group and placebo HCC group. However, deep datamining into GDSC dataset revealed our high PAX3 group in MVI + HCC related to resistance to sorafenib (P = 0.0039). Radiomics features were extracted from CT of MVI + HCC, and texture analysis in MVI + HCCs is ongoing. Conclusion: The proposed ceRNA network may help elucidate the regulatory mechanism by which lncRNAs function as ceRNAs and contribute to the pathogenesis of MVI in HCC. Importantly, the candidate lncRNAs, miRNAs, and mRNAs involved in the ceRNA network have shown to be potential therapeutic targets and prognostic biomarkers for MVI + HCC. PAX3 might play a vital role in the mechanism of sorafenib resistance in MVI + HCC, exclusively, this aggressive HCC subtype. The ongoing experiments on radiomics might add potent supports to identify sorafenib sensitive MVI + HCC. SAT502 In vivo performance of PEG-coated gold nanoparticles mediated ultrasound guided radiofrequency ablation: a pilot study in swine Tudor Mocan 1 , Popa Calin 2 , Pestean Cosmin 3 , Al Hajjar Nadim 4 , Saftoiu Adrian 5 , Zeno Sparchez 6 . 1 Institute for Gastroenterology and Hepatology, Cluj-Napoca, Romania, 3rd Medical Department, “Iuliu Hatieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania, Cluj-Napoca, Romania; 2 Institute for Gastroenterology and Hepatology, Cluj-Napoca, Romania, 3rd Surgical Department, “IuliuHatieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania, Cluj-Napoca, Romania; 3 University of Agricultural Sciences and Veterinary Medicine, Cluj-Napoca, Romania, Cluj-Napoca, Romania; 4 Institute for Gastroenterology and Hepatology, Cluj-Napoca, Romania, 3rd Surgical Department, “IuliuHatieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania, Cluj-Napoca, Romania; 5 Research Center of Gastroenterology and Hepatology Craiova, University of Medicine and Pharmacy Craiova, Craiova, Romania, Craiova, Romania; 6 Institute for Gastroenterology and Hepatology, Cluj-Napoca, Romania, 3rd Medical Department, “Iuliu Hatieganu” University of Medicine and Pharmacy Cluj-Napoca, Romania, Cluj-Napoca, Romania Email: mocan_tudor@yahoo.com Background and Aims: Radiofrequency ablation (RFA) is the first line treatment option for patients with small hepatocellular carcinoma and a recommended treatment modality for patients with hepatic metastases judged to be unfit for surgical intervention. However, RFA is still used mainly for lesions <3 cm, and despite all great advancements the ablation zone remains limited in volume. Gold nanoparticles offer the potential to heat tumour tissue selectively at the cellular level by non-invasive interaction with radiofrequency energy delivered externally. The objective of this study was to investigate the effects of polyethylene glycocol (PEG) coated gold nanoparticles intratumoral delivery on ablation zone volumes during in vivo RFA of porcine liver. Method: This prospective study was performed following institu- tional animal care and use committee approval. RFAwas performed in liver in ten Sus scrofa domesticus swine. PEG coated gold Figure: (abstract: SAT501) POSTER PRESENTATIONS S906 Journal of Hepatology 2020 vol. 73 | S653–S915