354 Investigating the B-cell response in patients with HPV+ head and neck cancer

Objectives/Goals: Intratumoral B-cells are associated with better survival, but their antigenic targets are unclear. Here, I will delineate B-cell responses in human papillomavirus (HPV)-positive head and neck cancer (HNC) patients against all major HPV E proteins to identify immunodominant responses. Methods/Study Population: To profile tumor-infiltrating antibody-secreting cells (ASCs), I will analyze freshly prepared single-cell suspensions of lymphocytes from HPV+ HNC tumors using ELISpot assays. To profile circulating memory B-cells in circulation, peripheral blood mononuclear cells obtained at time of surgery will be differentiated into ASCs, followed by ELISpot analysis. To assess systemic antibody titers, ELISAs will be performed on matched plasma samples. Due to the reliance on fresh tumor samples, our study population consists mostly of stage I HPV+ HNC patients, for which surgical resection is often the primary treatment option. Notably, HPV+ HNC is known to disproportionally affect males. Results/Anticipated Results: I will identify the immunodominant targets of the HPV-specific B-cell response in HPV+ HNC. Based on my preliminary data, I expect that the HPV-specific responses will primarily target E1, E2, and E4, as opposed to the classical oncoproteins E6 and E7. I expect the magnitude of the intratumoral HPV-specific ASC response to be reflected in the systemic antibody level, with systemic antibodies, thus serving as viable surrogates for intratumoral HPV-specific responses. Additionally, I expect minimal presence of intratumoral B-cell response against antigens unrelated to the tumor, such as influenza or Epstein–Barr virus, in contrast to abundant systemic antibody titers and memory B-cells. Discussion/Significance of Impact: The majority of current immunotherapeutic treatment options for this malignancy focus solely on targeting E6 and E7. However, if other HPV E proteins are shown to be more immunogenic, targeting these antigens could enable more efficient immunotherapies.