Unique conditionally replication competent bipartite adenoviruses-cancer terminator viruses (CTV): efficacious reagents for cancer gene therapy.

摘要

The frequent resistance of aggressive cancers to currently available therapies, such as radiotherapy and chemotherapy, mandates development of targeted, nontoxic and more efficacious treatment protocols. Conditionally replication competent adenoviruses (CRCAs) that induce oncolysis by cancer-specific replication are currently being evaluated in clinical trials. However, a single modality approach may not be sufficient to completely eradicate cancer in a patient, because most cancers arise from abnormalities in multiple genetic and signal transduction pathways. The promoter region of rodent progression elevated gene-3 (PEG-3), cloned and characterized in our laboratory, embodies the unique property of increased activity in a broad range of tumor cells, both rodent and human, when compared to normal counterparts. Bipartite adenoviruses were engineered to express the E1A gene, necessary for viral replication, under control of the PEG-3 promoter (PEG-Prom) and simultaneously express a second transgene in the E3 region that encodes an apoptosis-inducing and immunomodulatory cytokine, either immune interferon (IFN-gamma) or melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24). These conditionally replication competent bipartite adenoviruses, referred to as cancer terminator viruses (CTVs), facilitated cancer-selective adenovirus replication, robust transgene expression and apoptosis induction with complete eradication of both primary and distant (metastatic) human cancers xenotransplanted in athymic nude mice. These findings suggest that CTVs might prove efficacious for the therapy of primary and advanced neoplastic diseases.