m-PEG11-acid is a non-cleavable 11-unit polyethylene glycol (PEG) linker utilized in the synthesis of antibody-drug conjugates (ADCs) [1]. It is similarly employed as a PEG-based linker for PROTAC synthesis [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].