One promising immunotherapy is PROSTVAC-VF, cancer vaccine in phase III clinical trials for the treatment of advanced prostate cancer.[5] PROSTVAC-VF induces immunity to prostate-specific antigen (PSA) using genetically modified vaccinia and fowlpox encoding PSA and three costimulatory molecules (LFA-3, B7.1, and ICAM-1) [6]. The gene discussed is KLK3; the disease is cancer.