In recent years, various approaches to gene therapy have been significantly improved. In addition to the development of new techniques of "genome editing" (the targeted modification of DNA by so-called gene scissors), improved vector design was a major contribution to this. The use of lentiviral vectors for gene transfer in blood stem cells resulted in clinical successes in the treatment of hereditary immune defects, for example. It was possible to improve the methods for treating hereditary blood diseases such as hemophilia B, which are based on gene transfer to the liver, by using adeno-associated viruses as vectors. They also helped to advance the treatment of severe, hereditary eye diseases such as Leber's congenital amaurosis. 

Also noteworthy are the successes of the clinical studies that aimed to combat cancer using modified immune cells (T cells) (see also module Cancer therapies with CAR T cells).