Humanized VHH Antibody CDR Grafting for Immunogenicity Reduction
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Solution Overview
Problem
Camelid single-domain variable fragments of heavy-chain only antibodies (VHHs) require humanization to reduce immunogenicity, especially for repeated or long-term administration, but established methods like CDR grafting are not well-established due to poorly defined complementarity-determining regions (CDRs) in VHHs.
Innovation Solution
A CDR-grafting method is developed to humanize camelid VHHs by defining CDRs based on statistical distribution of antigen-contacting residues, using a database of crystal structures to improve VHH humanization, resulting in tetra-specific, octavalent IgG1 molecules with enhanced bio-activities, including neutralizing activity and broad reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If camelid VHHs are used for therapeutic applications, then they offer advantages in small size and ease of production, but they exhibit high immunogenicity requiring humanization
Solution Approach 1:
The patent applies parameter changes by systematically modifying the amino acid sequence parameters of VHH framework regions to match human antibody frameworks. This involves changing specific residues in framework regions while preserving CDR sequences, thereby reducing immunogenicity while maintaining antigen-binding capability and production advantages
Solution Approach 2:
The patent uses human antibody framework regions as intermediaries to bridge the gap between camelid VHH antigen-binding capability and human compatibility. The human framework serves as a mediator that reduces immunogenicity while allowing the non-human CDR regions to maintain their antigen-specific binding function
2Object-affected harmful factors
If CDR grafting method is used to humanize VHHs, then framework immunogenicity is reduced, but the method is not well-established due to poorly defined CDRs in VHHs
Solution Approach 1:
The patent segments the VHH structure into distinct functional regions: CDRs that maintain antigen-binding specificity and framework regions that are humanized to reduce immunogenicity. This segmentation allows selective modification of framework regions while preserving the integrity and function of CDR regions
Solution Approach 2:
The patent applies local quality by making different parts of the antibody molecule have different degrees of humanization. Specifically, framework regions are humanized to reduce immunogenicity, while CDR regions are preserved in their original camelid form to maintain antigen-binding specificity. This localized approach optimizes both immunogenicity reduction and binding function
Data Source
AI summary
Novel, antibody-based binding agents derived from camelid VHH and human immunoglobulins are described. These binding agents recognize and bind with specificity to Clostridium difficile toxin A and/or toxin B and in some cases exhibit toxin neutralizing activity. These binding agents can be used to treat or prevent primary and recurrent CDI. The binding agents include humanized VHH peptide monomers, linked groups of humanized VHH peptide monomers, humanized VHH peptide monomers joined to antibody Fc domains, and humanized VHH peptide monomers joined to IgG antibodies.