[The tumor microenvironment-relay station for prognosis and therapy response]

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide with a dismal prognosis. Besides tobacco and alcohol abuse, human papilloma virus (HPV) infection is an independent risk factor, particularly in oropharyngeal squamous cell carcinomas (OPSCC). One key determinant of therapy response and prognosis is the tumor immune microenvironment (TIME). A strong anti-tumor immune response represents an important mechanism of tumor cell killing. Another major determinant is the tumor metabolism. One feature of tumor cells is their reliance on glycolysis instead of oxidative phosphorylation (OXPHOS) for energy production despite sufficient oxygen supply.The presented studies were based on several different clinically and pathologically well annotated HNSCC cohorts. Immunohistochemical stainings were performed on tissue microarrays and whole slides against p16, different immune cell markers, and metabolic markers. DNA and mRNA were extracted to detect HPV and assess immune-related and metabolic genes via RT-PCR and Nanostring.An initial assessment of HPV infection frequencies in different HNSCC cohorts showed that socioeconomic and regional factors strongly influence HPV prevalence. An analysis of the immunological and metabolic differences of HPV-positive and HPV-negative OPSCC demonstrated an enhanced anti-tumor immune response together with increased levels of OXPHOS metabolism in HPV-positive OPSCC. In a subsequent study, a strong anti-tumor immune response together with an OXPHOS metabolism was associated with improved short-term survival in HNSCC. Finally, TIME differences of HNSCC primary tumors and recurrent tumors were analyzed to understand the poor therapeutic response of recurrences and discovered an overall decrease of tumor infiltrating lymphocytes with significant loss of CD8-positive T cells and B lymphocytes as well as a significant decrease of tertiary lymphoid structures in recurrences after chemoradiation.These results demonstrate the clinical and molecular differences of HPV-positive and HPV-negative HNSCC with a focus on OPSCC. Furthermore, they delineate the interdependencies of TIME and tumor metabolism in HNSCC in general and stress their impact on therapy response. Additionally, they show an impairment of anti-tumor immune response in recurrences after chemoradiation, which indicates immune evasion as one recurrence driver.