Antibodies against CTLA-4, PD-1 and PD-L1 can block the binding of CTLA-4 & CD80/86 on antigen presenting cells (APC) or the binding of PD-1 and PD-L1 on tumor cells, which can lead to binding of TCR and MHC causing T cell activation. Here, CTLA4 is linked to neoplasm.