Oral Bacteria In Feces Correlate To Neoadjuvant Immunochemotherapy In OSCC

This study aims to investigate the correlation between the oral-gut microbiome axis and the efficacy of neoadjuvant immunochemotherapy (NAICT) in locally advanced primary oral squamous cell carcinoma (OSCC), whose treatment response varies among patients. A prospective clinical trial was conducted on locally advanced primary OSCC patients receiving NAICT (n=35). Pathological responses of the primary tumor were evaluated by pathologists, who were blind to patients’ information. Salivary and fecal samples were collected before and after treatment for 16S amplicon sequencing. Connections between the oral and gut microbes were analyzed, focusing on responder (R) and non-responder (NR) groups based on pathological evaluation. Among 35 enrolled patients, a notable pathological response rate (22/35) was observed. After depicting the baseline features of oral and gut microbes, we identified high microbial overlaps in the predominant members of the oral-gut microbiome, and a significantly increased relative abundance of oral bacteria in feces, which negatively correlated with a depletion of gut bacteria in the NR group during NAICT, while the R group remained unchanged. Furthermore, the prediction model constructed based on microbiome and clinicopathological features demonstrated superior performance for therapeutic responses. This study highlights the influence of oral-gut microbiome on the variability of NAICT response, providing novel insights and potential biomarkers for personalized treatment strategies in OSCC.