Impact of HPV status on immune responses in head and neck squamous cell carcinoma

Abstract

The main objective of our study was to understand the impact of immune cell composition and the tumor-reactivity of tumor infiltrating lymphocytes (TIL) in HPV-positive (HPV⁺) and HPV-negative (HPV^-) head and neck squamous cell carcinoma (HNSCC). TIL cultures were established from primary HNSCC tumors, the T cell subsets were phenotypically characterized using flow cytometry, and Interferon (IFN)-γ ELISA assay was used to determine TIL function. NanoString Immune Profiler was used to determine an immune signature by HPV-status, and multiplex immunohistochemistry (MIHC) was used to quantify immune cell distributions and their spatial relationships. Results showed that HPV⁺ and HPV^- HNSCC had similar capacity to expand IFN-γ reactive TIL populations, and these TIL populations had similar characteristics. NanoString analysis revealed increased differential expression of genes related to B cell functions in HPV⁺ HNSCC, which were significant at a Benjamini-Yekutieli adjusted p-value of < 0.001. MIHC also displayed increased CD8⁺ T cell and CD19/CD20⁺ B cell densities in the tumor region of HPV⁺ HNSCC as opposed to HPV^- HNSCC (p < 0.01). Increases in a combined metric of tumor B cell content and stromal plasma cell content was associated with increased progression-free survival in HPV^- HNSCC patients treated with immune checkpoint inhibitor therapy (p = 0.03). In summary, TIL populations expanded from HPV⁺ and HPV^- HNSCC displayed similar IFN-γ reactivity. However, we identified a strong B-cell signature present within HPV⁺ HNSCC, and higher B and plasma cell content associated with improved PFS in HPV^- HNSCC patients treated with immune checkpoint inhibitors.

Keywords: HPV-associated cancer; Head and neck cancer; Immunotherapy; Tumor infiltrating lymphocytes; Tumor microenvironment.