Impact of dipeptide on ADC physicochemical properties and efficacy identifies Ala-Ala as the optimal dipeptide

Side chains of natural occurring Amino acids vary greatly in terms of charge state, polarity, size and hydrophobicity. Using a linear synthetic route, two Amino acids were sequentially coupled to a potent Glucocorticoid Receptor modulator (GRM) to afford a library of dipeptide-GRM linker payloads with a range of in silico properties. The linker payloads were conjugated to a mouse anti-TNF antibody through interchain disulfide Cys. Impact of various dipeptide linkers on ADC physical properties, including solubility, hydrophobicity, and aggregation were evaluated and the in silico properties pI, Log P and tPSA of the linker drugs used to correlate with these properties. ADCs were screened in a GRE luciferase reporter assay to compare their in vitro efficacy. Data identified Ala-Ala as a superior dipeptide linker that allowed a maximum drug load of 10 while affording ADCs with low aggregation.