Abstract 4530: Single-cell analysis of oral squamous cell carcinoma (OSCC) from smoker vs. non-smoker patients highlights two groups of tumors with distinct immune microenvironments

Background and Rationale: OSCC is the most frequent head and neck cancer. While it is mainly affecting patients with a smoking and/or alcohol history (SD), 10% to 15% of OSCC are diagnosed in patients with not known risk factors (NSND). We and others have shown that OSCC from NSND patients are characterized by an enrichment in interferon gamma (IFNγ) response and PD-1 signaling pathways together with a higher intratumor T-cell infiltrate. Herein, we seek to gain more insights into the immune and non-immune tumor microenvironment (TME) of OSCC in SD vs. NSND patients. Material and Methods: We made use of single-cell RNA seq (10x Genomics) from non-sorted and CD45 negative enriched cell suspensions of OSCC biopsies from 11 treatment naïve patients, human papillomavirus negative, including 6 SD and 5 NSND patients. Results: All samples were characterized by a strong immune cell infiltrate. Consistent with our previous results, the analysis of 51,629 immune cells confirmed that NSND patients’ samples displayed a significantly higher proportion of T cells (p = 0.005) compared to SD patients. NK cells were also increased, with 2% in SD patients versus 6% in NSND patients (p = 0.008). T cells strongly expressed IFNγ and remarkably, both myeloid cells and tumor cells from NSND patients had an increased enrichment in IFNγ response pathway in NSND as compared to SD patients. The TME of SD patients was characterized by the presence of 15% of plasma cells vs. 3% in NSND patients (p = 0.003). Thus, tumors from NSND versus SD patients represent two distinct groups of tumors characterized by a different immune TME. Moreover, tumors from SD patients displayed 2% vs. 4% Cancer Associated Fibroblasts (CAFs) (p = 0.01). In addition, among CAFs subpopulations, myofibroblast CAFs, defined as the subpopulation producing extracellular matrix proteins were found only in tumors from SD patients, suggesting that distinct CAFs subpopulations may shape the immune TME by affecting the recruitment and function of adaptive immune cells in SD versus NSND patients. Finally, we analyzed tumor cells using non-negative matrix factorization to find Meta Programs (MP), which are set of genes coordinately upregulated. We identified 5 MP associated with different biological functions: epithelial differentiation, stress, cell cycle (G2/M), partial epithelial-to-mesenchymal transition, and epithelial senescence. While the epithelial differentiation MP was found in all patients, the remaining ones were more frequently found in SD patients. Conclusion: Our results show that the TME of OSCC from NSND vs. SD differs in terms of T, NK, and plasma cells composition, CAFs, and tumor cells MP. Integration with spatial transcriptomics is ongoing. Those biological differences may represent an opportunity to refine the therapeutic approaches in the two populations of patients. Citation Format: Yannick Le Meitour, Béatrice Vanbervliet, Sonia Canjura-Rodriguez, Cyril Degletagne, Laurie Tonon, Lucas Michon, Jebrane Bouaoud, Philippe Zrounba, Aude Excoffier, Karène Mahtouk, Pierre Saintigny. Single-cell analysis of oral squamous cell carcinoma (OSCC) from smoker vs. non-smoker patients highlights two groups of tumors with distinct immune microenvironments. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4530.