Novel Method for Engineering Aggregation-Resistant Antibody Fragments

Protein aggregation is a significant challenge in developing safe and effective therapeutic antibodies. We are investigating how antibody fragments can be engineered to possess extremely high solubility without altering binding activity. Although we find that hydrophobic peptides can be introduced into the complementarity-determining regions (CDRs) of single-domain antibodies in a rational manner to mediate specific binding to the Alzheimer’s and Parkinson’s polypeptides (Perchiacca et al., PNAS, 2012; Ladiwala et al., PNAS, 2012), these hydrophobic loops also mediate antibody aggregation. Therefore, we have developed a novel approach for engineering the edges of hydrophobic CDRs with charged mutations that dramatically increases antibody solubility without reducing their binding affinity. In contrast, similar mutations within the antibody scaffold and non-CDR loops are ineffective at preventing aggregation. We are currently using this mutational strategy for engineering several high-affinity antibody fragments and full-length antibodies to improve their solubility.