Salivary Microbiome Relates to Neoadjuvant Immunotherapy Response in OSCC.

Area of Science:

• Oncology
• Microbiome Research
• Immunotherapy

Background:

• Oral squamous cell carcinoma (OSCC) often presents at advanced stages with poor prognoses.
• Immunotherapy offers survival benefits but suffers from low response rates.
• The oral microbiome's role in tumor immunity and immunotherapy response remains under investigation.

Purpose of the Study:

• To explore the association between the salivary microbiome and immunotherapy response in OSCC patients.
• To identify potential salivary microbiome biomarkers predicting immunotherapy efficacy.

Main Methods:

• Salivary metagenome sequencing in 47 OSCC patients undergoing neoadjuvant immunotherapy (NAIT).
• Classification of patients into responders and nonresponders based on pathological outcomes.
• Development and validation of a nomogram predicting NAIT efficacy using salivary bacterial levels.

Main Results:

• Nonresponders had lower salivary microbiome species richness than responders pre-NAIT.
• Specific bacterial species, notably lower levels of Eubacterium infirmum, Actinobaculum, and Selenomas (EAS), were associated with nonresponse.
• Low salivary EAS levels correlated with reduced intratumoral immune cell infiltration and predicted nonresponse with an AUC of 0.81.

Conclusions:

• Salivary microbiome profiles differ between immunotherapy responders and nonresponders in OSCC patients prior to treatment.
• Low salivary EAS abundance is a potential predictive biomarker for identifying nonresponders to NAIT in OSCC.
• EAS-associated metabolic pathways may influence immunotherapy response in OSCC.