Several investigational products are currently being developed using engineered replication-competent arenavirus, including the clinical stage vectors HB-202/HB-201 for HPV+ cancers and vectors that express key prostate cancer antigens (prostate-specific antigen, prostatic acid phosphatase, and prostate-specific membrane antigen) that are nearing the clinic for the treatment of prostate cancer. The gene discussed is ACP3; the disease is cancer.