Catherine Huynh, BS: No financial relationships to disclose
Introduction/Rationale: Lung cancer remains a leading cause of cancer mortality, with non-small cell lung carcinoma (NSCLC) comprising over 80% of cases. While immunotherapies have improved survival, challenges persist in overcoming tumor-driven immunosuppression and sustaining effective immune activation. Emerging evidence suggests the lung microbiome may influence these immune processes, yet its role in shaping NSCLC progression remains poorly defined.
Methods: Three human lung microbiome datasets were analyzed to identify microbial features of NSCLC, controlling for tissue type, therapy, smoking, and antibiotic use. Reads were processed with DADA2 and annotated via KEGG and MetaCyc. Two murine models were used: a K-Ras mutant model induced by intratracheal Cre recombinase, and xenografts (KP-NINJA, KP-HELLO) expressing neoantigens to recruit immune subsets. Mice were exposed intratracheally to heat-inactivated Burkholderia (health-associated), Veillonella dispar (disease-associated), or Klebsiella LPS (control).
Results: Human NSCLC tissues showed significantly reduced microbial diversity and metabolic activity, indicating a loss of microbial integrity with disease. In mice, immunotherapy preserved microbial diversity and structure in proportion to tumor regression, while neoantigen-expressing tumors that promoted immune infiltration similarly restored microbial balance. Direct administration of health-associated microbes enhanced immune cell infiltration and reduced tumor burden, whereas disease-associated microbes suppressed immune engagement and promoted tumor persistence. Spatial mapping revealed microbial byproducts colocalized with innate immune cells, supporting their role in amplifying anti-tumor immunity through local signaling networks.
Conclusion: These findings uncover a dynamic interplay between lung microbes and tumor immunity. Modulating microbial composition can reshape immune responses, presenting a novel strategy to improve NSCLC immunotherapy outcomes.
