CTLA4 and neoplasm: The original view that CTLA-4:CD80 and PD-1:PD-L1 binding between TCRs and ligands in other cells (trans binding) are at the essence of tumour immune evasion, was recently enriched with the knowledge that PD-L1 also binds to CD80 when these molecules are overexpressed in the same cell (cis-CD80:PD-L1) but not when they are in different cells (no trans-CD80:PD-L1)38.