Background: The incidence of human papilloma virus-associated oropharyngeal cancer (HPVOPC) has rapidly risen over the past two decades. Foreign viral antigens make HPVOPC an attractive target for immunotherapy. One exciting approach is the use of live attenuated Listeria monocytogenesbioengineered to express the HPV16 E7 protein (LmE7) and elicit a vigorous immune response. We designed a phase II “window of opportunity” trial with robust correlative endpoints to determine the effect of LmE7 vaccination on anti-tumor immunity in the tumor microenvironment and peripheral blood, as well as safety and tolerability in the HPVOPC population. Methods: Trial Design: Non-randomized single-arm phase II clinical trial utilizing a Simon’s two-stage design. HPVOPC patients receive two cycles of LmE7 over 5 weeks prior to standard-of-care transoral surgical resection of their tumor with or without neck dissection. The primary objective is to determine the rate of post-vaccination T cell responses by measuring the pre- and post-treatment mean frequency of peptide-specific IFN-γ expressing T cells in the peripheral blood by ELISPOT. We will conclude that LmE7 is likely highly immunogenic and worth further investigation if post-treatment responses are seen in > 75% of patients. Inclusion Criteria:Previously untreated surgically-resectable stage II-IV HPVOPC, HPV-positive by PCR-based testing. Exclusion Criteria:Prior history of cancer within 3 years, or any history of systemic cancer therapy; immunosuppressive disorder or medications; medical contraindications to therapy. Correlative Studies:The pattern of immunocyte infiltration in the tumor and draining lymph nodes will be assessed by multiplex immunofluorescence; expression profile of immune-related genes assessed by nanostring; and T cell receptor diversity by deep sequencing. These tissue-based changes will be correlated with comprehensive analysis of immune changes in the peripheral blood Status: Open, actively accruing. 8 of a maximum 22 (9 in first stage, 13 in second stage) vaccinated patients, and 0 of a maximum 10 untreated observational cohort patients have been enrolled. Clinical trial information: NCT02002182