The primary objective of this phase II study is to determine whether pembrolizumab increases the tumor infiltrating and peripheral blood immune response to the VRP-HER2 vaccine. The investigators hypothesize that HER2 specific T cell responses and anti-tumor immunity induced with HER2 vaccination will be augmented by concurrent anti-PD-1 antibody therapy.~The investigators will additionally determine whether the administration of pembrolizumab is safe in patients with recurrent or metastatic HER2+ cancers who are receiving the anti-HER2 vaccine VRP-HER2.~There will be an initial Safety Arm (n=3) during which subjects will receive the VRP-HER2 immunizations plus pembrolizumab and if there is no dose limiting toxicity in the Safety Arm, subjects will then be randomized 1:1:1 into 3 arms (n=12 per arm). Subjects with metastatic HER2 overexpressing breast cancer receiving trastuzumab and pertuzumab will continue these antibodies. They will undergo a biopsy of their tumor and peripheral blood draw for immune cell analyses and be assigned to the applicable arm of the study. Arm A will consist of the the VRP-HER2 immunizations; Arm B will consist of pembrolizumab; Arm C will consist of the VRP-HER2 immunizations plus pembrolizumab. Tumor biopsies and peripheral blood draws will be performed following the course of immunizations.
In this phase II study, study subjects will receive the VRP-HER2 immunizations plus pembrolizumab. There will be an initial Safety Arm during which subjects will receive the VRP-HER2 immunizations plus pembrolizumab. If there is no dose limiting toxicity in the Safety Arm, then subjects will be randomized into 3 arms. They will undergo a biopsy of their tumor and peripheral blood draw for immune cell analyses and be assigned to the applicable arm of the study. Arm A will consist of the the VRP-HER2 immunizations; Arm B will consist of pembrolizumab; Arm C will consist of the VRP-HER2 immunizations plus pembrolizumab.