PRIMARY OBJECTIVE:~I. To determine pathologic and human papillomavirus cell-free tumor deoxyribonucleic acid (ctHPVDNA) response to liposomal HPV-16 E6/E7 multipeptide vaccine PDS0101 (PDS0101) or PDS0101 plus pembrolizumab in patients with high risk human papillomavirus-associated oropharynx cancer (HPV-OPSCC).~SECONDARY OBJECTIVES:~I. To determine tumor response by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1.~II. To determine progression-free survival and overall survival.~TERTIARY OBJECTIVES:~I. To determine the safety of PDS0101 delivered alone or with pembrolizumab.~CORRELATIVE RESEARCH OBJECTIVES:~I. Determine the changes in tumor microenvironment (TME) with PDS0101 alone or with pembrolizumab.~II. Determine circulating ctHPVDNA as a biomarker for tumor response. III. Determine HPV16-specific T-cell response utilizing multiplex flow cytometry and other parameters.~OUTLINE: Patients are randomized to 1 of 2 arms.~ARM A: Patients receive liposomal HPV-16 E6/E7 multipeptide vaccine PDS0101 (PDS0101) subcutaneously (SC) on day 1. Treatment repeats every 21 days for up to 2 cycles in the absence of disease progression or unacceptable toxicity.~ARM B: Patients receive PDS0101 SC on day 1 and pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment repeats every 21 days for up to 2 cycles in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed every 3 months for up to 2 years.
This phase I/II trial studies how well PDS0101 alone or in combination with pembrolizumab works to shrink tumor in patients with human papillomavirus-associated oropharynx cancer that has spread to nearby tissue or lymph nodes (locally advanced). PDS0101 is a vaccine made from specific peptides that may help the body build an effective immune response to kill tumor cells. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving PDS0101 with or without pembrolizumab may kill more tumor cells in patients with locally advanced human papillomavirus-associated oropharynx cancer before surgery so that it may make the tumor smaller and may reduce the amount of normal tissue that needs to be removed.