SPDP-Val-Cit-PAB-PNP is a cleavable ADC linker featuring an SPDP group, a Val-Cit dipeptide, a para-aminobenzyl (PAB) spacer and a para-nitrophenyl (PNP) carbonate group. SPDP is a thiol-specific covalent linker which forms disulfide bonds with cysteine residues of proteins. Val-Cit-PAB is a protease-cleavable linker which is designed for efficient payload release upon proteolysis. Finally, PNP is a good leaving group which is activated towards nucleophilic attack such as from amines.