ABSTRACT

The identification of unknown functional genes has induced the propagation of new and modern medical treatments like gene vaccination and gene therapy. These novel therapies try to cure illnesses at the genetic level (genotype) and not by treating symptoms (phenotype). Although gene therapy as a treatment for diseases still holds great promises, the progress in developing effective clinical protocols has been slow over the last 15 years (1). A critical point lies in the development of safe and efficient gene transfer systems. In addition, efforts need to be undertaken with regard to difficulties encountered during the manufacturing and industrial production of stable gene delivery systems as well as with patient compliance. The first clinically approved study for somatic gene therapy started in September 1990 (2). In the intervening 15 years, approximately 1000 gene therapy clinical trials have been initiated worldwide [according to statistics published in The Journal of Gene Medicine, 2006; (3)]. More than 60% of the clinical trials were

performed in the United States, whereas about 30% were in Europe and the remaining studies took place in Asia and Australia. Most of the trials are performed in early clinical phases (phase I and phase I/II, approximately 84%), 13% in phase II, and only 3% in late clinical phases (phase II/III and phase III).