Specifically, a vaccinia virus engineered to either express B7-1 alone or in combination with the cell adhesion molecules ICAM-1 and lymphocyte function-associated antigen 3 (LFA-3) (the triplet combination termed TRICOM) can provide an optimised form of co-stimulation required by anti-tumour CD8+ T-cells and has demonstrated efficacy and tolerability in several early-phase clinical trials in patients with malignant melanoma [143]. This evidence concerns the gene CD8A and melanoma.