Targeted cancer gene therapy: The flexibility of adenoviral gene therapy vectors

Recombinant adenoviral vectors are promising reagents for therapeutic interventions in humans, including gene therapy for biologically complex diseases like cancer and cardiovascular diseases. In this regard, the major advantage of adenoviral vectors is their superior in vivo gene transfer efficiency on a wide spectrum of both dividing and non-dividing cell types. However, this broad tropism at the same time represents an important limitation for their use in therapeutic applications where specific gene transfer is required. This limitation may be overcome by using targeting approaches. In this regard, targeting may be achieved at three levels: transductional targeting, translational targeting and targeting of the expressed transgene. Here we describe our research efforts towards cancer specific gene therapy using these different targeting approaches. The results show that targeting of adenoviral vectors may be achieved using cancer specific cell surface molecules for transductional and transgene targeting or cancer specific promoters for transcriptional targeting. Combinations of these targeting approaches should result in optimized cancer specific gene therapy.