Disulfide-Stabilized TfR1 Binder for Monomeric BBB Transport
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Solution Overview
Problem
Existing antibodies and antibody fragments targeting the transferrin receptor 1 (TfR1) for brain delivery face challenges such as interference with normal TfR1 function, stability issues, and aggregation, particularly when binding to the apical domain, which can lead to safety concerns and reduced transport efficiency across the blood-brain barrier.
Innovation Solution
A TfR1 binding molecule that targets the protease-like domain of TfR1 using a disulfide-stabilized Fv fragment (dsFv) with specific cysteine residues at positions 44 and 100, avoiding the apical domain, thereby enhancing stability and preventing multimerization, ensuring monomeric binding and efficient transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If antibodies bind to the apical domain of TfR1, then BBB transport efficiency is improved, but stability and monomeric binding are compromised leading to aggregation
Solution Approach 1:
The antibody is segmented into separate heavy chain (HC) and light chain (LC) variable domains that are independently expressed and then assembled. This segmentation allows for separate optimization of each domain's stability and binding properties, preventing aggregation while maintaining BBB transport efficiency through the disulfide bridge-stabilized interface between HC and LC
Solution Approach 2:
The patent creates a composite molecular structure by forming a disulfide bridge between cysteine residues in the HC and LC variable domains. This composite HC-LC structure with covalent bonding provides enhanced stability and prevents aggregation while maintaining the antigen-binding capability needed for efficient BBB transport
2Reliability
If antibodies target the apical domain of TfR1, then binding affinity is enhanced, but interference with normal TfR1 function increases
Solution Approach 1:
The patent modifies specific local regions of the antibody structure by introducing cysteine residues at defined positions in the HC and LC variable domains. This local modification creates a disulfide bridge that stabilizes the antibody-TfR1 interaction at the binding interface, enhancing affinity while the overall binding mode avoids disrupting TfR1's normal function
3Productivity
If conventional antibody formats are used for TfR1 targeting, then BBB transport is achieved, but multimerization and aggregation occur
Solution Approach 1:
The patent performs preliminary stabilization by forming a disulfide bridge between HC and LC variable domains before the antibody encounters TfR1 or undergoes potential aggregation. This pre-established covalent connection prevents multimerization and aggregation events that would otherwise occur with conventional antibody formats, ensuring monomeric binding and efficient BBB transport
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The TfR1 binding molecule achieves stable, monomeric binding to TfR1, minimizing interference with normal TfR1 function and improving transport efficiency across the blood-brain barrier, while reducing safety risks associated with aggregation.
Implementation Method 1
comprises one first cysteine residue in said VH region and one second cysteine residue in said VL region, said first and second cysteine residues being arranged such that they form a disulfide bridge connecting the VH and VL regions
Data Source
AI summary
The present disclosure relates to a stabilized binding molecule, for example an antibody or antigen-binding fragment thereof, which binds to the protease-like domain of human transferrin receptor 1 (TfR1), and to therapeutic and diagnostic uses thereof.