Data from preclinical studies indicate that a proprietary, non-viral gene delivery system controlled by Introgen Therapeutics, Inc results in prolonged expression of delivered genes in mice implanted with human lung tumours. Introgen's collaborators at The University of Texas M.D. Anderson Cancer Center conducted the studies and the data appeared in a recent issue of Molecular Therapy in a paper titled "Persistent Transgene Expression Following Intravenous Administration of a Liposomal Complex: Role of Interleukin-10-Mediated Immune Suppression."

Previous studies have demonstrated that non-viral delivery of lipid-DNA complexes induces strong immune responses in animals and humans. These immune responses result in only short-term expression of therapeutic genes and limit the use of systemic therapy with non-viral systems. Additionally, these immune responses reduce the effectiveness of subsequent injections administered within a few days. The current data provide the first evidence that the immune response to non-viral vectors is different between animals with and without tumours. Gene expression persists longer in animals with tumours compared with those without. Furthermore, repeated injections of the non-viral vector produce enhanced effects in animals bearing tumours. The data suggest that the difference in immune response is mediated through IL-10, a protein known to suppress immune function. IL-10 expression was higher in mice with tumours than in those without.

Dr. Sunil Chada, Introgen's director of research and development said, "We believe these data will be applicable to patients with cancer, as we know that many patients with lung cancer overproduce immunosuppressive cytokines. Thus we believe that our non-viral formulation may produce robust and persistent gene expression in cancer patients. This in turn may lead to enhanced therapeutic effects and improved clinical outcomes."

Introgen is a leading developer of biopharmaceutical products designed to induce therapeutic protein expression using non-integrating gene agents for the treatment of cancer and other diseases.