This trial found no evidence that non-viral 1 fibroblast growth factor (NV1FGF) is effective in the reduction of amputation or death in patients with critical limb ischaemia. The trial was conducted as a multinational, double-blind, placebo-controlled phase 3 randomised gene therapy study in 525 patients with critical limb ischaemia. The authors note that critical limb ischaemia is the most severe form of peripheral artery disease (PAD) and develops in 2% to 5% of patients with PAD. Fibroblast growth factor type 1 (FGF1) is involved in modulating and promoting new blood-vessel formation and promotes development of capillaries from pre-existing vessels through activation of various cellular processes.