DBCO-PEG-8-Val-Cit-PAB-PNP is a cleavable ADC linker featuring a BCN group, a hydrophilic PEG spacer, a Val-Cit dipeptide, a para-aminobenzyl (PAB) spacer and a para-nitrophenyl (PNP) carbonate group. DBCO is a click chemistry handle which readily reacts with azide groups on a target molecule, while the PNP carbonate acts as a highly activated leaving group which may be used to react with amines. The use of cleavable linkers in the development of ADCs allows a medicinal chemist to decide the point where the drug payload is released to the cell. Val-Cit-PAB linkers are cleaved by cytoplasmic peptidases.
