Antibody Humanization via Framework Assembly
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Solution Overview
Problem
Current methods for humanizing antibodies, such as rational design and empirical methods, face challenges including reduced antigen binding affinity and reliance on structural biology or large libraries, which limit their efficiency and applicability in generating high-affinity humanized antibodies.
Innovation Solution
A novel framework-assembly method that constructs libraries of heavy and light chain variable domains from human germline sequences, allowing for the expression and selection of humanized antibodies through phage display and affinity ranking, bypassing the need for structural information and large libraries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CDR grafting is used to humanize antibodies, then immunogenicity is reduced and serum half-life is prolonged, but antigen binding affinity decreases significantly
Solution Approach 1:
The patent applies local quality by selectively modifying only specific framework regions (FR2 and FR3) rather than the entire antibody structure. This localized approach allows restoration of CDR loop conformations that directly contact antigen, while maintaining the overall humanized structure that reduces immunogenicity. The framework residues involved are precisely identified through structural analysis and replaced with matching sequences from parental murine antibodies.
Solution Approach 2:
The patent changes the amino acid sequence parameters of framework regions to restore high affinity. By replacing specific framework residues with those from parental murine antibodies, the patent optimizes the conformational parameters of CDR loops, enabling them to maintain proper spatial arrangement for antigen binding while preserving the humanized backbone structure.
2Manufacturing precision
If rational design methods are used for antibody humanization, then structural control is improved, but the process becomes complex and requires structural biology expertise
Solution Approach 1:
The patent extracts and focuses only on the critical framework regions (FR2 and FR3) that directly influence CDR loop conformation and antigen binding. By isolating these specific regions for modification rather than analyzing the entire antibody structure, the patent simplifies the rational design process while maintaining structural control over the most important functional elements.
Solution Approach 2:
The patent segments the antibody structure into functionally distinct regions, treating framework regions and CDR loops as separate modules. This segmentation allows independent optimization of framework residues to support CDR conformation, while CDR sequences are grafted from parental antibodies. The modular approach reduces process complexity by focusing on discrete functional units rather than the entire antibody structure.
3Manufacturing precision
If empirical methods with large libraries are used, then high affinity antibodies can be isolated, but the method requires construction of large combinatorial libraries
Solution Approach 1:
The patent performs preliminary action by pre-identifying and replacing critical framework residues before library construction. By using structural analysis to determine which framework regions are most important for CDR conformation and antigen binding, the patent prepares optimized framework sequences in advance. This preliminary optimization reduces the need for large library sizes, as the critical structural determinants are already in place before empirical selection begins.
Data Source
AI summary
An improved method for producing humanized antibody or an antigen binding fragment thereof is described. The method, designated framework-assembly, bypasses the reliance on structural biology and the construction of large libraries. It is easier to implement and more efficient than the rational design and empirical methods. Also described are humanized antibodies produced by the method and related framework-assembly library.