Antibody Framework 3 Insertion for Bispecific Stability
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Solution Overview
Problem
Current antibody fragments, such as Fv, Fab, and F(ab')2, suffer from increased clearance from serum due to the lack of the Fc domain, which affects their pharmacokinetics and stability, and existing methods for creating bispecific antibodies are complex and inefficient, often resulting in steric hindrance issues.
Innovation Solution
Development of antibodies comprising a variable (V) domain with an insert polypeptide within the framework 3 region, which enhances binding affinity and pharmacokinetics, allowing for stable bispecific binding without significant hindrance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If antibody fragments (Fv, Fab, F(ab')2) are used, then tissue penetration and pharmacokinetic properties are improved, but clearance from serum increases due to lack of Fc domain
Solution Approach 1:
The patent inserts a second antibody or antibody fragment into the framework 3 region of the first antibody's variable domain, creating a nested structure where one antibody is contained within another. This nested configuration allows the outer antibody to provide Fc domain-mediated long serum half-life while the inner antibody contributes to binding functionality, resolving the contradiction between rapid clearance and extended duration.
Solution Approach 2:
The invention creates a bispecific antibody structure where the outer antibody provides Fc domain functions (long serum half-life via FcRn interaction) while the inner antibody provides binding specificity. This multi-functional design allows a single molecule to simultaneously achieve both rapid tissue penetration through the compact fragment structure and extended serum half-life through Fc domain engagement.
2Adaptability or versatility
If chemical cross-linking is used to create bispecific antibodies, then hetero- and homo-dimer formation is achieved, but yields are poor and chromatographic separation is required
Solution Approach 1:
The patent merges two antibody molecules into a single integrated bispecific structure by inserting one antibody into the framework 3 region of another, eliminating the need for separate dimer formation steps. This merging approach achieves high yields of functional bispecific antibodies without requiring chromatographic separation, as the insertion method inherently produces the correct stoichiometry and configuration.
3Adaptability or versatility
If protein engineering approaches (knobs-into-holes) are used, then bispecific antibody formation is achieved, but the process becomes highly elaborate
Solution Approach 1:
The invention segments the antibody structure into distinct functional components: an outer antibody providing Fc domain functions and an inner antibody providing binding specificity. This segmentation allows each component to be independently optimized and expressed, then combined through the framework 3 insertion method, significantly simplifying the overall engineering process compared to knobs-into-holes approaches while achieving the desired bispecific functionality.
4Adaptability or versatility
If diabodies or scFv are used, then bispecific binding is achieved, but stability characteristics are inappropriate
Solution Approach 1:
The patent creates a composite antibody structure combining an outer antibody with an inner antibody or antibody fragment inserted into its framework 3 region. This composite design provides the stability of a full-length antibody through the outer Fc domain while incorporating the bispecific binding capability through the inner antibody component, achieving both appropriate stability characteristics and functional versatility.
Data Source
AI summary
The present invention provides antibodies comprising a variable (V) domain and an insert polypeptide, wherein the insert polypeptide is within the framework 3 region of the V domain.