Oral Microbiome Diversity Matters on Nucleos(t)ide Analogue Cessation in Chronic Hepatitis B

Background Withdrawal of nucleos(t)ide analog (NUC) therapy in HBeAg-negative chronic hepatitis B (CHB) may lead to functional cure in a subset of patients. Although gut microbiota is known to influence both CHB-progression and treatment outcomes, the oral microbiome in NUC-cessation remains unexplored. Methods This long-term longitudinal study aimed to explore the oral microbiome in CHB patients who have been on NUC therapy >2 years having a planned NUC cessation. Oral microbiome composition was analyzed in 110 saliva samples across seven timepoints from 18 HBeAg-negative patients with 36 months of follow-up. Favorable outcome was defined as either HBsAg loss or decline of >1 log10 or sustained off-therapy HBV DNA level <2000 IU/ml during year 3. Hepatic flare was defined as ALT >80 U/L or 2x baseline level. Results The overall microbial composition remained stable during the study period. Patients with favorable outcome (n=8) showed consistently higher alpha diversities (Shannon and Simpson indices, p<0.001) from baseline, with lower inter-sample variations across all timepoints (Bray-Curtis and Jaccard distances, p<0.05), compared to unfavorable (n=10). HBsAg, ALT and AST correlated inversely with several Prevotella taxa with specific pathways (Spearman´s rho>-0.5, p<0.01). Unfavorable outcome and high HBsAg level correlated with opportunistic taxa Haemophilus parainfluenzae and Porphyromonas catoniae at multiple timepoints. Random forest model incorporating ANCOM-validated microbial markers predicting favorable vs unfavorable outcome achieved higher predictive performance than clinical markers alone (AUC 0.78 vs. 0.66). Conclusion Our exploratory study suggests that oral microbiome profiling at NUC cessation in HBeAg-negative CHB could support prognostication of virological outcome.