Alkyne-Val-Cit-PAB-PNP is a cleavable ADC linker which contains a terminal alkyne, a valine-citrulline (Val-Cit dipeptide, and a para-nitrophenyl (PNP) carbonate. The alkyne group is a click chemistry handle which readily reacts with azide groups on a target molecule to form stable triazole linkages, while the PNP may be used to react with amines. Val-Cit linkers are cleaved by cytoplasmic peptidases.