Tumor-specific promoters could induce a specific expression of therapeutic genes in a type of tumor increasing their localized activity, as described by Rama et al., using CEA to direct E gene expression towards colon cancer cells [45] Phael et al. also demonstrated the anticancer and selective potential of Clostridium perfringens enterotoxin (CPE) in vivo, using an intratumor CPE vector transfer in a patient-derived subcutaneous xenograft model derived from a metastatic colorectal tumor, that led to tumor growth inhibition [46]. The gene discussed is CPE; the disease is colonic neoplasm.