A method of assessing the safety of a
gene therapy vector comprising: providing a
population of genetically modified cells 18 wherein the cells have been transfected with a vector; exposing the genetically edited cells to a
carcinogen 20; growing the cells to produce immortal
cell lines; and comparing the survival of the test cells with a control 14 to determine if the vector contributes to carcinogenicity. Also claimed is a method of testing the safety of a vector comprising: providing test cells; genetically editing the cells with a vector and exposing cells to a
carcinogen or exposing the cells to a
carcinogen and modifying the cells with a vector; growing the cells; and comparing the survival of the cells to a control. The cells may be used in
immunotherapy. The cells may be CAR-T cells. The cells may be from
peripheral blood mononuclear cells or induced pluripotent stem cells (iPSCs). The carcinogen may be ENUA. Also claimed is a method of designing a vector for use in
gene therapy by harvesting
nucleic acid from the test cells, characterising the modification of the test cells, redesigning the vector, and repeating the method of testing the safety of the vector.