HPV-associated head and neck cancer is characterized by distinct profiles of CD8+ T cells and myeloid-derived suppressor cells

Abstract

Patients with HPV^--localized head and neck cancer (HNC) show inferior outcomes after surgery and radiochemotherapy compared to HPV-associated cancers. The underlying mechanisms remain elusive, but differences in immune status and immune activity may be implicated. In this study, we analyzed immune profiles of CD8⁺ T cells and myeloid-derived suppressor cells (MDSC) in HPV⁺ versus HPV^- disease.The overall frequency of CD8⁺ T cells was reduced in HNC versus healthy donors but substantially increased after curative therapy (surgery and/or radiochemotherapy). In HPV⁺ patients, this increase was associated with significant induction of peripheral blood CD8⁺/CD45RA^-/CD62L^- effector memory cells. The frequency of HPV-antigen-specific CD8⁺ cells was low even in patients with virally associated tumors and dropped to background levels after curative therapy. Pre-therapeutic counts of circulating monocytic MDSC, but not PMN-MDSC, were increased in patients with HPV^- disease. This increase was accompanied by reduced fractions of terminally differentiated CD8⁺ effector cells. HPV^- tumors showed reduced infiltrates of CD8⁺ and CD45RO⁺ immune cells compared with HPV⁺ tumors. Importantly, frequencies of tumor tissue-infiltrating PMN-MDSC were increased, while percentages of Granzyme B⁺ and Ki-67⁺ CD8 T cells were reduced in patients with HPV^- disease.We report differences in frequencies and relative ratios of MDSC and effector T cells in HPV^- HNC compared with more immunogenic HPV-associated disease. Our data provide new insight into the immunological profiles of these two tumor entities and may be utilized for more tailored immunotherapeutic approaches in the future.

Keywords: CD8+ T cells; HPV; Head and neck cancer; MDSC; Oropharyngeal cancer.