Single-Chain CD3 Binding Proteins for Human–Cynomolgus Cross-Reactivity
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Solution Overview
Problem
Existing anti-CD3 antibodies face challenges in achieving optimal binding affinity and cross-reactivity with both human and cynomolgus monkey CD3 proteins, limiting their therapeutic efficacy in T cell activation.
Innovation Solution
Development of single chain variable fragment CD3 binding proteins with specific amino acid sequences, including complementarity determining regions (CDRs) and framework residues, that exhibit enhanced binding affinity and cross-reactivity with both human and cynomolgus CD3, achieved through optimized linker lengths and amino acid compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing anti-CD3 antibodies are used, then T cell activation can be achieved, but binding affinity and cross-reactivity with human and cynomolgus monkey CD3 proteins are insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the amino acid sequences of CDR regions (HC CDR1-3 and LC CDR1-3) with specific residue specifications to enhance binding affinity. The linker length between VH and VL is also optimized (e.g., (GGGGS)n where n=2-5) to improve protein stability and binding characteristics, directly resolving the contradiction between achieving reliable binding and maintaining cross-species adaptability.
Solution Approach 2:
The patent applies local quality by making specific amino acid substitutions in key CDR regions while maintaining framework regions. For example, HC CDR1 follows the pattern GX1X2X3NX4YX5X6N with specific residue options at each position, allowing localized optimization of binding interface without compromising overall protein structure, thereby improving both binding affinity and cross-reactivity.
2Quantity of substance
If single chain variable fragment structure is used, then protein size is reduced and T cell activation is facilitated, but achieving optimal binding affinity becomes more challenging
Solution Approach 1:
The patent applies segmentation by separating the antibody into variable heavy chain (VH) and variable light chain (VL) domains connected by a peptide linker, creating a single-chain format. This segmentation reduces protein size compared to full antibodies while maintaining binding functionality through optimized CDR regions and linker design, resolving the contradiction between size reduction and binding affinity maintenance.
Solution Approach 2:
The patent merges VH and VL domains into a single polypeptide chain through a flexible linker sequence, allowing the fragment to function as a complete antigen-binding unit. This merging maintains binding affinity despite reduced size by preserving the spatial arrangement of CDR loops through the linker-mediated connection between heavy and light chain variables.
3Reliability
If optimized amino acid sequences are implemented, then binding affinity to human and cynomolgus CD3 is enhanced, but protein complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific amino acid patterns for each CDR region (e.g., HC CDR2: RIRSX7X8NX9YX10TX11YX12DX13VK) with constrained residue options at each position. This systematic parameter optimization enhances binding affinity through rational design while managing sequence complexity through structured patterns rather than random sequences.
Data Source
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AI summary
Disclosed herein are single chain variable fragment CD3 binding proteins with improved binding affinities, and robust aggregation profiles. Also described are multispecific binding proteins comprising a single chain variable fragment CD3 binding protein according to the instant disclosure. Pharmaceutical compositions comprising the binding proteins disclosed herein and methods of using such formulations are provided.