Ex-vivo gene therapy of human vascular bypass grafts with E2F decoy: the PREVENT single-centre, randomised, controlled trial

Background Cell-cycle blockade by ex-vivo gene therapy of experimental vein grafts inhibits the neointimal hyperplasia and subsequent accelerated athe rosclerosis that lead to human bypass-graft failure. In a prospective, rand omised, controlled trial, we investigated the safety and biological efficac y of intraoperative gene therapy in patients receiving bypass vein grafts. Methods We studied gene therapy that uses decoy oligodeoxynucleotide, which binds and inactivates the pivotal cell-cycle transcription factor E2F. 41 patients were randomly assigned untreated (16), E2F-decoy-treated (17), or scrambled-oligodeoxynucleotide-treated (eight) human infrainguinal vein gra fts. Oligonucleotide was delivered to grafts intraoperatively by ex-vivo pr essure-mediated transfection. The primary endpoints were safety and inhibit ion of target cell-cycle regulatory genes and of DNA synthesis in the graft s. Analysis was by intention to treat. Findings Mean transfection efficiency was 89.0% (SD 1.9). Proliferating-cel l nuclear antigen and c-myc mRNA concentrations and bromodeoxyuridine incor poration were decreased in the EF2-decoy group by medians of 73% [IQR 53-84 ], 70% [50-79], and 74% [56-83], respectively) but not in the scrambled-oli godeoxynucleotide group (p<0.0001). Groups did not differ for postoperative complication rates. At 12 months, fewer graft occlusions, revisions, or cr itical stenoses were seen in the E2F-decoy group than in the untreated grou p (hazard ratio 0.34 [95% CI 0.12-0.99]). Interpretation Intraoperative transfection of human bypass vein grafts with E2F-decoy oligodeoxynucleotide is safe, feasible, and can achieve sequence -specific inhibition of cell-cycle gene expression and DNA replication. App lication of this genetic-engineering strategy may lower failure rates of hu man primary bypass vein grafting.