PD1⁺CD8⁺ Cells Are an Independent Prognostic Marker in Patients with Head and Neck Cancer

Head and neck squamous cell carcinomas (HNSCCs) belong to a group of diverse tumors, which can be induced by infection with human papillomavirus (HPV) or tobacco and alcohol consumption. The viral etiology of HNSCC relates to better clinical outcomes reflecting a different immune system response. Here, we retrospectively analyzed 97 tissue samples from oral and oropharyngeal carcinomas associated and non-associated with HPV infection using multispectral fluorescent immunohistochemistry. To evaluate the immune cell infiltration in tumor and stroma compartments, we designed four panels of four to five antibodies. We detected more T lymphocytes in the stroma, compared to the tumor parenchyma. In HPV positive (HPV⁺) in comparison to HPV negative (HPV^-) tumors, higher counts of CD3⁺CD4⁺, CD3⁺CD8⁺, PD1⁺CD4⁺, PD1⁺CD8⁺ T cells, and ICOS^- Treg cells were detected while more ICOS⁺ Treg cells and CTLA4⁺CD4⁺ T cells were observed in HPV^- than in HPV⁺ tumors. The results of the univariate and multivariate analyses confirmed the predominant impact of HPV status on prognosis. More importantly, the number of CD8⁺PD-1⁺ T cells was identified as an independent factor, influencing the overall and/or disease-specific survival of patients with oral cavity or oropharyngeal carcinomas.