The ability of therapeutic antibodies to recognize their target antigens with high specificity in the complex <i>in vivo</i> environment is crucial to their function as safe and efficacious drugs. However, therapeutic antibodies, especially those discovered or engineered using <i>in vitro</i> methods such as phage or yeast surface display, often display variable levels of non-specific interactions that lead to drug development challenges such as low bioavailability and fast antibody clearance. Therefore, we have developed methods for predicting sites in antibody variable regions linked to off-target binding and for designing antibody libraries that softly randomize such sites with residues predicted to improve antibody specificity. We have evaluated this approach for improving the specificity of multiple clinical-stage antibodies that display high levels of off-target binding. To accomplish this, we have displayed our designed antibody libraries on the surface of yeast, sorted them based on their affinity for multiple types of reagents (including their target antigens and several polyspecificity reagents), and used deep sequencing methods to identify rare variants that retain high target affinity and display increased specificity. Importantly, we find that a subset of antibody sites that mediate non-specific binding do not overlap with those involved in antigen binding. We will discuss our identification of such sites and how we are exploiting them to engineer antibodies with drug-like specificity.

Specificity engineering of clinical-stage antibodies

ACS Fall 2020 Virtual Meeting

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