Bis-PEG2-PFP ester is a non-cleavable 2-unit polyethylene glycol (PEG) linker employed in the synthesis of antibody-drug conjugates (ADCs) [1]. Additionally, Bis-PEG2-PFP ester serves as a PEG-based linker for the synthesis of proteolysis targeting chimeras (PROTACs) [2].

ADCs are comprised of an antibody to which is attached an ADC cytotoxin through an ADC linker[1]. PROTACs contain two different ligands connected by a linker; one is a ligand for an E3 ubiquitin ligase and the other is for the target protein. PROTACs exploit the intracellular ubiquitin-proteasome system to selectively degrade target proteins[2].