Cancer Targeted Gene Therapy of BikDD Inhibits Orthotopic Lung Cancer Growth and Improves Long-term Survival

Lung cancer is a leading cause of cancer death due to the high incidence of metastasis; therefore novel and effective treatments are urgently needed. A current strategy is cancer specific targeted gene therapy. While many identified cancer specific promoters are highly specific, they tend to have low activity compared to the ubiquitous CMV promoter, limiting their application. We developed a targeted gene therapy expression system for lung cancer that is highly specific with strong activity. Our expression vector uses the survivin promoter, highly expressed in many cancers but not normal adult tissues. We enhanced the survivin promoter activity comparable to the CMV promoter in lung cancer cell lines using an established platform technology, while the survivin promoter remained weak in normal cells. In mouse models, the transgene was specifically expressed in the lung tumor tissue, compared with the CMV promoter that was expressed in both normal and tumor tissues. Additionally, the therapeutic gene BikDD, a mutant form of pro-apoptotic Bik, induced cell killing in vitro, and inhibited cell growth and prolonged mouse survival in vivo. Importantly, there was virtually no toxicity when BikDD was expressed with our expression system. Thus, the current report provides a therapeutic efficacy and safe strategy worthy of development in clinical trials treating lung cancer.