Recombinant Antibody CH2 Domain Modifications for Enhanced Effector Activity
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Solution Overview
Problem
Current therapeutic antibodies, such as human IgG1 and IgG3, have limitations in terms of effector functions like ADCC and CDC activities, and there is a need for enhanced therapeutic effects without compromising antigenicity or production costs, particularly in maintaining protein-A binding activity.
Innovation Solution
A recombinant human IgG1 antibody with modified CH2 and CH3 domains, incorporating specific amino acid substitutions at positions 276 and 339, and featuring complex-type N-glycoside-linked sugar chains with reduced fucose attachment, enhances CDC and ADCC activities while maintaining protein-A binding capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amino acid substitutions are made at positions 276 and 339 in the CH2 domain to enhance CDC activity, then complement-dependent cytotoxic activity is improved, but protein-A binding activity may be compromised
Solution Approach 1:
The patent applies parameter changes by specifically substituting amino acids at positions 276 and 339 in the CH2 domain with variants that enhance CDC activity while preserving protein-A binding. This targeted parameter modification resolves the contradiction by optimizing the amino acid sequence to simultaneously improve effector function and maintain manufacturability.
Solution Approach 2:
The invention applies local quality by making specific amino acid substitutions only at positions 276 and 339 in the CH2 domain, rather than throughout the entire antibody structure. This localized modification enhances CDC activity in the specific region responsible for complement binding while leaving other functional regions, including protein-A binding sites, intact.
2Reliability
If amino acid substitutions are made to enhance effector functions, then therapeutic efficacy is improved, but antigenicity may increase
Solution Approach 1:
The patent uses parameter changes by selecting amino acid substitutions that enhance effector functions while maintaining human-like sequences. The substitutions at positions 276 and 339 are chosen to improve CDC and ADCC activities while preserving the overall human IgG1 structure, thereby reducing immunogenicity compared to non-human sequences.
Solution Approach 2:
The invention applies copying by using human amino acid sequences as templates for the substitutions. By copying amino acid variants found in human IgG isotypes (such as IgG3) at positions 276 and 339, the patent enhances effector functions while maintaining compatibility with the human immune system, thus reducing antigenicity.
3Reliability
If complex-type N-glycoside-linked sugar chains with reduced fucose attachment are incorporated, then ADCC activity is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the glycosylation pattern to reduce fucose attachment at specific N-glycoside sites in the Fc region. This parameter modification enhances ADCC activity by creating high-manose or afucosylated glycoforms that have increased affinity for FcγRIIIa receptors on immune cells, while the changes are achieved through controlled bioprocessing rather than complex structural redesign.
Data Source
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AI summary
The present invention relates to a recombinant antibody composition which is a human IgG1 antibody, comprises a CH2 domain in which amino acids at positions 276 and 339 indicated by the EU index as in Kabat, et al. are replaced by other amino acids and has more improved complement-dependent cytotoxic activity than an antibody comprising a CH2 domain before the amino acids are replaced; a DNA encoding the antibody molecule or a heavy chain constant region of the antibody molecule contained in the recombinant antibody composition; a transformant obtainable by introducing the DNA into a host cell; a process for producing the recombinant antibody composition using the transformant; and a medicament comprising the recombinant antibody composition as an active ingredient.