Cysteine-Engineered Antibody Variable Region for Site-Specific ADC Conjugation
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Solution Overview
Problem
Traditional non-site-specific conjugation methods for antibody-drug conjugates (ADCs) face challenges such as homogeneity issues and complex production processes due to the oxidation of sulfhydryl groups on cysteine residues during cell culture.
Innovation Solution
The development of cysteine-engineered antibodies with engineered cysteine residues at specific positions in the heavy and light chain variable regions, allowing for site-specific conjugation and maintaining partially active sulfhydryl groups for direct use in conjugation reactions without reduction treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional non-site-specific conjugation methods are used for ADCs, then the production process is simpler, but the homogeneity of ADCs deteriorates
Solution Approach 1:
The patent introduces cysteine residues at specific local positions (e.g., positions 26, 97, 102, 118 in the heavy chain variable region) to enable site-specific conjugation. This local modification approach maintains production feasibility while dramatically improving ADC homogeneity by restricting conjugation to defined sites rather than allowing random conjugation throughout the antibody structure.
2Manufacturing precision
If cysteine residues are engineered for site-specific conjugation, then ADC homogeneity is improved, but the production process becomes more complex due to oxidation of sulfhydryl groups
Solution Approach 1:
The patent performs preliminary engineering of cysteine residues at specific positions during antibody construction, positioning them in regions that remain accessible and reactive. This preliminary action enables direct conjugation without requiring subsequent reduction steps, as the engineered cysteines maintain their sulfhydryl groups in a reactive state throughout expression and purification, thereby simplifying the overall production process while achieving high homogeneity.
Solution Approach 2:
The patent changes the physical-chemical parameters of the antibody by introducing specific cysteine residues at defined positions with controlled solvent accessibility. This parameter change allows the sulfhydryl groups to remain stable and reactive under standard culture conditions, eliminating the need for complex reduction and re-oxidation steps in the production process.
3Stability of the object's composition
If cysteine residues are oxidized during cell culture, then the antibody structure is stabilized, but the sulfhydryl groups become inactive for conjugation
Solution Approach 1:
The patent strategically positions cysteine residues at specific local sites (e.g., positions 26, 97, 102, 118 in heavy chain variable region) that are spatially separated from the antibody's core disulfide bond structures. This local quality differentiation allows the engineered cysteines to maintain reactive sulfhydryl groups while the rest of the antibody structure remains stable through its native disulfide bonds.
Solution Approach 2:
The engineered cysteine residues act as intermediaries between the antibody structure and the drug conjugation process. By positioning these cysteines at specific locations with appropriate solvent accessibility, they serve as dedicated conjugation sites that do not interfere with the stability-maintaining disulfide bonds elsewhere in the antibody, thus preserving both structural stability and conjugation activity.
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
This approach improves the homogeneity of ADCs, simplifies the production process, and maintains the activity of the antibodies, leading to increased efficacy of the drug and reduced toxic side effects.
Implementation Method 1
Most of the sulfhydryl groups on cysteine that are introduced into the antibodies through cysteine engineering can be oxidized during cell culture, such as by reacting with the sulfhydryl groups on free cysteine in the cell culture medium to form disulfide bonds.
Implementation Method 2
The site-specific conjugation technique is not only applicable to intact IgG antibody molecules, but also applicable to a scFv and the scFv-based bispecific antibody-drug conjugates. The most common reactive amino acid in the site-specific conjugation technique is cysteine.
Data Source
Figure 1(A)~1(C)
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AI summary
The present disclosure provides a mutant of an antibody, and use thereof. Specifically, according to the Kabat numbering system, the mutant of the antibody has an engineered cysteine residue at any one or more position(s) selected from: positions 12, 34, 35, 38, 44, 47, 51, 60, 61, 67, 69, 78, 79, and 114 of the heavy chain variable region, or any combination thereof; or positions 19, 21, 44, 46, 47, 48, 62, 71, 75, 78, and 87 of the light chain variable region, or any combination thereof. The sulfhydryl group on the engineered cysteine can remain partially active in the antibody expression process. The active sulfhydryl group can be directly used to react with other active groups without reduction treatment. The cysteine-engineered antibody of the present disclosure can obtain the active groups for conjugating a drug, which is conducive to simplifying the production process of the antibody-drug conjugates, improving the homogeneity of the antibody-drug conjugates, increasing the efficacy, and reducing the toxicity and side effects.