CEACAM5 and cancer: To test our hypothesis that a robust transgene expression capability of AAV vectors can be exploited for breaking immune tolerance to a “self” antigen and to function as an efficacious cancer vaccine, we created a recombinant AAV (rAAV) by first sub-cloning human CEA (hCEA) into the open reading frame of pAAV-MCS plasmid under the control of a human cytomegalovirus (CMV)-chicken beta-actin hybrid promoter (Figure 1A).