Humanization by CDR grafting and specificity-determining residue grafting

Area of Science:

• Immunology
• Biotechnology
• Protein Engineering

Background:

• Humanized antibodies are engineered to reduce immunogenicity compared to murine antibodies.
• CDR grafting is a common method for humanization, but residual murine components can still elicit an immune response.

Purpose of the Study:

• To minimize the immunogenic potential of CDR-grafted humanized antibodies.
• To investigate the efficacy of specificity-determining residue (SDR) grafting for further antibody refinement.

Main Methods:

• CDR grafting was performed, retaining key murine framework residues for antigen-binding.
• Specificity-determining residues (SDRs) within CDRs were identified using 3D structural analysis and mutational data.
• SDRs and CDR loop-stabilizing residues were grafted onto a human antibody template.
• Immunogenic potential was assessed by measuring reactivity against sera from patients immunized with the parental antibody.

Main Results:

• SDR grafting effectively reduced the murine content in humanized antibodies.
• The engineered antibodies maintained their antigen-binding capabilities.
• Reduced reactivity was observed in patient sera assays, indicating lower immunogenicity.

Conclusions:

• SDR grafting represents a promising strategy for further reducing the immunogenicity of humanized antibodies.
• This approach enhances the therapeutic potential of engineered antibodies by improving their safety profile.