NH2-PEG1-Val-Cit-PAB-OH is a cleavable ADC linker with a primary amine, a hydrophilic PEG spacer, a Val-Cit dipeptide, and a PAB group. The benzyl alcohol on the PAB group facilitates conjugation reactions with groups like PNP for binding drug payloads. The primary amine is versatile in participating in reactions such as coupling with carboxylic acids, reductive amination with ketones or aldehydes, and more specialized applications like SNAr reactions or heterocyclic chemistry. The Val-Cit dipeptide is cleaved by intracellular proteases, allowing efficient payload delivery through an elimination mechanism within the PAB structure.