Structure-based engineering of a monoclonal antibody for improved solubility

Protein aggregation is of great concern to pharmaceutical formulations and has been implicated in several diseases. We engineered an anti-IL-13 monoclonal antibody CNTO607 for improved solubility. Three structure-based engineering approaches were employed in this study: (i) modifying the isoelectric point (pI), (ii) decreasing the overall surface hydrophobicity and (iii) re-introducing an N-linked carbohydrate moiety within a complementarity-determining region (CDR) sequence. A mutant was ident-ified with a modified pI that had a 2-fold improvement in solubility while retaining the binding affinity to IL-13. Several mutants with decreased overall surface hydropho-bicity also showed moderately improved solubility while maintaining a similar antigen affinity. Structural studies combined with mutagenesis data identified an aggregatio