In this respect, Ad-REIC/DKK-3 (adenoviral vector encoding the full-length DKK-3 gene) has been proposed as a non-genotoxic gene-based therapy, alone or in combination with conventional antineoplastic treatments, for several cancers such as prostate, testicular, glioma or breast cancer [53,54,57,58] (see Section 4). The gene discussed is DKK3; the disease is cancer.