Protein aggregation is one of the most significant challenges in developing safe and effective therapeutic antibodies. The complementarity-determining regions (CDRs) of antibodies – which mediate high-affinity binding to target antigens – can also mediate antibody aggregation. It remains unclear to what extent the CDRs of antibodies can be engineered to improve solubility without reducing binding affinity. Therefore, we have used structure-based methods to identify potential aggregation hotspots within the CDRs of a poorly soluble, multi-domain antibody (Fab) fragment, and systematically introduced positively and negatively charged mutations within each identified CDR. We find that some CDRs are highly permissive to mutations and multiple mutations of either polarity can be introduced that improve solubility without altering binding affinity. Other CDRs are moderately sensitive and tolerate only to a limited set of solubilizing mutations. We will discuss these findings in relation to our structure-based predictions and how they can be used to guide future efforts in engineering aggregation-resistant antibodies.

Structure-based design of CDR mutations that increase the solubility of multi-domain antibody fragments

249th National Meeting (2015)

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