Preclinical studies of recombinant adenovirus expressing IFNα along with gene transfer enhancing agent Syn3 (rAd-IFNα/Syn3) demonstrated tumour regression of bladder cancer in murine models while achieving sustained high levels of IFNα in both urine and urothelium [30,31,32]. The gene discussed is IFNA2; the disease is urinary bladder cancer.