For example, xenogeneic DNA vaccines targeting human tyrosinase were approved to treat canine melanoma [349], Xenovaccines designed with rhesus CEA (rhCEA) as the immunogen against human carcinoembryonic antigen (hCEACAM-5 or commonly hCEA) can activate CD4+ T cells and autoreactive CD8+ T cells, and produce high-titer antibodies against hCEA and have significant anti-tumor effects. Here, CD4 is linked to neoplasm.