Intercepting the Evolution of Pro-Tumoral Myeloid Cells During the Initiation of Oral Cancer

PROJECT SUMMARY/ABSTRACT Earlier detection and treatment of human papillomavirus (HPV)-negative head and neck squamous cell carcinomas (HNSCC) has the greatest potential to improve overall survival rates, which have remained stagnant at around 50% for several decades. Patients with HPV-negative HNSCC often have a clinical history of oral epithelial dysplasia (OED), but it remains unclear which lesions will progress to cancer. Through comprehensive sequencing of these tumors, it is known that a common (about 20%) genetic alteration event is the amplification at locus 3q26.3, which harbors oncogene SOX2 (SRY-box transcription factor 2). Previous research revealed that SOX2 inhibits a critical immune sensing pathway by degrading stimulator of interferon genes (STING) protein in HNSCC cancer cells. The activation of the STING pathway is essential for establishing a spontaneous anti-tumor immune response, as it promotes the presentation of tumor antigens on the surface of myeloid cells, leading to the activation of cancer-killing T cells. It remains unclear how STING signaling in tumor-resident immune cells may be impacted during SOX2-driven malignant transformation. To investigate this, we have developed a preclinical mouse model to study the transition from OED to HNSCC. Upon high-dimensional analysis of the immune landscape, we find a unique myeloid cell phenotype that suppresses anti-tumor immune response. This study will utilize a multipronged approach to investigate the mechanism by which myeloid cells in SOX2-positive lesions develop terminal suppressive phenotypes. We will test pharmacological and genetic strategies to intercept the evolution of these pro-tumoral myeloid cells. Ultimately, this project will provide a high- resolution atlas of functionally distinct myeloid cell subsets in precancerous lesions and identify key interception points for therapeutic intervention.