Supplementary Material for: Differences in the intestinal microbiome associated with diarrhea during lenvatinib treatment for hepatocellular carcinoma

Introduction: Lenvatinib has been widely used for the treatment of advanced hepatocellular carcinoma (HCC). Some adverse events, including diarrhea, have been reported for lenvatinib. Diarrhea may be associated with the changes in the intestinal microbiome; however, the underlying mechanism have not been elucidated. Aim: In this study, we aimed to investigate the relationship between the intestinal microbiome and diarrhea caused by lenvatinib via analysis of fecal samples collected before treatment. Methods: A total of 21 patients with advanced HCC who were treated with lenvatinib were enrolled. Fecal samples were collected from patients. The patients were divided into diarrhea (n=8) and non-diarrhea groups (n=12). We compared the characteristics of patients, incidence of adverse events, composition of the intestinal microbiome, and enrichment of functional pathways between both groups using QIIME2 and PICRUSt2. Results: The median age of the two groups was 73 years. The non-diarrhea group comprised a relatively higher number of male patients than the diarrhea group however, there were no significant differences in patient characteristics between both groups. The proportion of the microbiome was similar, and alpha and beta diversities were not significantly different between both groups. The relative abundance of order Bacteroidales, including Parabacteroides and Prevotella, was higher in the diarrhea group than in the non-diarrhea group. PICRUSt2 analysis showed some metabolic pathways, including butanoate (butyrate) metabolism, were enriched in the non-diarrhea group when compared with those in the diarrhea group. Conclusion: Differences in the intestinal microbiomes and their functions may influence the incidence of diarrhea during lenvatinib treatment.