The aim of this study is to show the feasibility of controlling arthritis severity by an apoptosis-inducing gene therapy strategy targeting the FLSs in arthritic joints. HAdV5 vectors have been widely used as gene transfer vectors for cancer therapy. However, the use of HAdV5 vectors for arthritis treatment are limited as FLSs are poorly transduced and attempts to improve the gene transfer efficacy by genetic modification of the vector were not satisfactory13, 16. The innovation in the present study is the development of a strategy for efficient HAdV5 gene transfer to FLS coupled to a potent apoptosis-inducing gene for the treatment of chronic synovitis.