Bivalent Bispecific Antibody Assembly with scFv and Asymmetric Disulfides
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Solution Overview
Problem
Existing bispecific antibodies face challenges with high mismatched assembly rates of light and heavy chains, low affinity for antigens, and inappropriate molecular sizes, leading to inefficient tumor therapy.
Innovation Solution
A bivalent bispecific antibody design incorporating single-chain variable fragments (scFv), flexible peptides, and modified heavy chain hinge regions with disulfide bonds and 'knob-hole' structures to enhance correct assembly and affinity, using a recombinant expression system in host cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cell fusion or chemical conjugation is used to produce bisspecific antibodies, then dual antigen binding capability is achieved, but mismatched assembly of light and heavy chains occurs leading to low yields and complicated purification
Solution Approach 1:
The patent applies asymmetry by introducing a cysteine residue at position 221 of the heavy chain to create a unique disulfide bond configuration. This asymmetric modification ensures that light chains correctly pair with their corresponding heavy chains through specific disulfide bonds, preventing mismatched assembly while maintaining dual antigen binding capability.
Solution Approach 2:
The patent changes the chemical parameter of the heavy chain by adding a cysteine residue at position 221, which alters the bonding characteristics. This parameter change enables the formation of specific disulfide bonds that control chain assembly correctness, resolving the contradiction between versatility and manufacturing precision.
2Adaptability or versatility
If traditional bisspecific antibody structures are used, then dual antigen recognition is achieved, but molecular size becomes inappropriate for efficient tumor therapy
Solution Approach 1:
The patent segments the antibody structure by using a single-chain variable fragment (scFv) configuration where the variable regions are connected by a flexible linker. This segmentation creates a more compact structure that maintains dual antigen recognition while reducing overall molecular size for better tumor penetration and therapeutic efficiency.
3Adaptability or versatility
If recombinant expression technology is used to produce bisspecific antibodies, then dual specificity is achieved, but mismatched by-products are still generated requiring complicated purification
Solution Approach 1:
The asymmetric introduction of a cysteine residue at heavy chain position 221 creates a unique bonding pattern that enables correct assembly. This asymmetry ensures that only the intended light-heavy chain pairs form stable complexes, significantly reducing mismatched by-products and simplifying purification processes while maintaining dual specificity.
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 antibody achieves high affinity for both antigens, ensuring a moderate molecular size and improved assembly rates, enhancing tumor therapy efficacy.
Implementation Method 1
modified heavy chain hinge regions with disulfide bonds
Data Source
AI summary
Provided are a bivalent bispecific antibody and a preparation method thereof, a coding gene, a host cell and a composition. The bivalent bispecific antibody comprises: a) a single-chain variable fragment scFv, a flexible peptide, a heavy chain IgG1 constant region CH1 and a hinge region partial sequence of the antibody that specifically binds to a first antigen, and b) a single-chain variable fragment scFv, and a light chain constant region CL, that is, scFv1-CL or CL-scFv1, of the antibody that specifically binds to a second antigen; or comprises: c) a light chain and a heavy chain of the antibody that specifically binds to the first antigen, and d) a light chain and a heavy chain of the antibody that specifically binds to the second antigen.