Poxvirus-based active immunotherapy initially targets specific tumor antigens encoded by the viral vector (e.g. PSA, HER-2, CEA or MUC-1); however, T cell-mediated tumor killing holds the potential to reveal antigen spread T cell responses to de novo patient-specific antigens (also known as private antigens or neoantigens). This evidence concerns the gene MUC1 and neoplasm.