Figure 3.

Evaluation of mutations that reduce viscosity at high antibody concentrations. (a) The impact of Fv mutations that modify antibody charge on viscosity was systematically evaluated to test the role of charge-related properties in mediating viscous antibody behavior. Systematic alteration of Fv charge in an anti-PDGF antibody rarely resulted in reduced viscosity, even when predicted to reduce viscosity by multiple conventional scoring methods. (b) Antibody variants with modest reductions in viscosity achieved in Round 1 (green) were further optimized in Round 2 through mutagenesis of negatively charged patches in the variable regions, which produced two antibody mutants that could be concentrated above 150 mg/mL while maintaining low viscosity (<20 cP). (c) Fv charge partially but incompletely describes the viscosity behavior, demonstrating the complicated relationship between antibody viscosity and charge properties. The figure is adapted with permission from a previous publication.⁷⁷