HPV-Associated Immunosuppression Following Radiotherapy in Head and Neck Squamous Cell Carcinoma

Summary: Head and neck squamous cell carcinoma (HNSCC) is a highly aggressive malignancy, ranking as the seventh most common cancer in the United States. HPV-positive HNSCC, especially oropharyngeal cancer, typically triggers a strong antitumor response, which generally leads to better overall survival rates (1). Combining immunotherapy with radiation therapy (RT) shows promise for treating HPV-positive HNSCC due to the intricate interactions between the virus and the host (2). Despite this, the lack of response in some patients highlights the need to address significant challenges in their treatment to distinguish responders (Rs) from non-responders (NRs) in HPV-associated carcinoma patients (3). In our prior research, we found that RT enhanced the production of myeloid cells in the bone marrow, leading to increased circulating myeloid-derived suppressor cells (MDSCs). RT is a crucial component of HNSCC treatment. However, it can cause immune suppression by increasing suppressor cell levels and altering cytokine profiles, potentially worsening patient prognosis and treatment outcomes. Our findings indicate that despite a heightened immune response in HPV-positive HNSCC patients, they still experience radiation-induced immune suppression. This study investigates how HPV status affects the radiation-induced expansion of suppressor cells and its impact on immune suppression and prognosis in HNSCC. We conducted a comprehensive analysis of circulating immune cells and pro-inflammatory cytokines in 13 patients with HNSCC undergoing chemoradiotherapy. Using multi-color flow cytometry, we assessed the myeloid and lymphoid panels with optimized antibodies, and pro-inflammatory cytokines were measured using a bead-based panel from LegendPlex. Using Comprehensive immune analysis, we found that radiation therapy significantly increased the levels of monocytic MDSCs (M-MDSCs) in the peripheral blood of HNSCC patients (P=0.0195). Correspondingly there was a significant decrease in CD4+ and CD8+ T-cells (CD4: P=0.0033, CD8: P=0.0043) in the patients after RT. Additionally, we found that MCP-1 and IL8 were elevated after RT in all HNSCC patients. The HPV+ (P16) patients were more immunosuppressed than HPV-after RT probably due to higher levels of MDSCs. Furthermore, ROC curve analysis of the lymphocyte frequency showed a significant association between lymphopenia and patients that were HPV positive (AUC:0.88, P < .05). The findings from this study indicated that RT enhances MDSCs which could contribute to increased immunosuppression in HNSCC patients. HPV plays a potential role in modulating immunity via MDSCS. Aous Jarrouj (he/him/his), MD, MBA, MHM (Presenting Author) - University of Oklahoma; Saeede Soleimanian (she/her/hers), PhD (Co-Author) - University of Oklahoma; sandeep Sriramanujam, PhD (Co-Author) - University of Oklahoma; Jerry Jaboin, MD, PhD, MBA, FACRO, FASTRO (Co-Author) - University of Oklahoma Health Sciences Center; Christina Henson, MD (Co-Author) - University of Oklahoma; dinesh Thotala (he/him/his), PhD, MBA (Co-Author) - University of Oklahoma