Alteration of gut microbiota in patients with advanced hepatocellular carcinoma.

641 Background: Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the third leading cause of cancer-related death worldwide. Despite advancements in treatment, such as novel combinations of immunotherapy and targeted therapy or dual immunotherapy, the prognosis remains poor due to a lack of predictive biomarkers for treatment response. Gut microbiota alterations have been proposed as both potential diagnostic biomarker and predictive biomarker. However, data in this field are not well-established and are mostly derived from studies conducted in China and Western countries, which may not fully reflect the situation in Thailand. Methods: Fecal samples were collected from pre-treated advanced HCC patients who visited medical oncology outpatient clinic at Srinagarind hospital, Khon Kaen University (HCC group = 27) and analyzed using 16S rRNA sequencing of gut microbiota. Additional sequenced data from a healthy population (Control group = 31) who had no underlying disease and had normal liver ultrasonography were retrieved from a previous study conducted by Khon Kaen University (Cholangiocarcinoma Screening and Care Program, CASCAP). The datasets were compared using the Wilcoxon rank-sum test to analyze the alteration of gut microbiota between HCC group and control group. Results: The HCC group exhibited significantly lower biodiversity index (p< 0.001) than control group in terms of richness, Shannon diversity index and Simpson’s index. The HCC group had significantly higher relative abundance of the phylum Proteobacteria (p< 0.001), Firmicutes (p< 0.001) and a lower abundance of the phylum Actinobacteria (p< 0.001) compared to the control group. Additionally, the HCC group had significantly higher relative abundance of Stenotrophomonas, Granulicatella, Ruminococcus, Blautia, Phascolarctobacterium, Butyricoccus, Streptococcus, Escherichia-Shigella, Flavonifractor, Haemophilus and Lachnospira at the genus level. Further analysis of relative abundance of gut microbiota at the genus level and clinical prognostic parameters showed positive correlation between Streptococcus and 6-month survival status. Conclusions: Gut microbiota profile in patients with advanced HCC was significantly altered from healthy control group. This could be the evidence of microbial dysbiosis and may potentially be biomarker for prognosis.