Human Fc Variants for Selective FcγRIIa Binding and Longer Half-Life
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Solution Overview
Problem
Existing antibody therapeutic agents face challenges in enhancing the half-life and selective binding to Fcγ receptors, particularly FcγRIIa, while reducing binding to the inhibitory FcγRIIb, which affects their ADCC and ADCP efficacy.
Innovation Solution
Development of human Fc domain variants with specific amino acid substitutions, such as C229R, G236A, Q311R, P396L, and M428L, that improve pH-dependent binding to FcRn and enhance selective binding to FcγRIIa, thereby increasing the A/I ratio and ADCP induction ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If genetic mutations are introduced to increase binding capacity to activating FcγR, then ADCC and ADCP induction ability is improved, but binding capacity to inhibiting FcγRIIb may increase simultaneously due to high structural homology
Solution Approach 1:
The patent applies local quality by making specific amino acid substitutions at particular positions (e.g., L327, L328, Q311, M428) in the Fc domain to selectively enhance binding to activating FcγR while maintaining or reducing binding to inhibiting FcγRIIb. This localized modification approach allows differential binding properties at different receptor interaction sites within the Fc domain.
Solution Approach 2:
The patent changes physical-chemical parameters of the Fc domain through amino acid substitutions that alter electrostatic interactions, hydrogen bonding, and van der Waals forces at specific receptor binding interfaces. These parameter changes enable selective modulation of binding affinity to different FcγR types based on their distinct structural characteristics.
2Reliability
If Fc domain is modified to enhance FcγRIIa binding selectivity, then ADCP efficiency is improved, but pH-dependent binding to FcRn may be affected
Solution Approach 1:
The patent segments the Fc domain into distinct functional regions: the FcγR binding interface (residues 230-250, 300-440) and the FcRn binding interface (residues 230-250, 400-440). By making targeted substitutions in overlapping but distinct sub-regions, the patent independently optimizes binding to activating FcγR while preserving pH-dependent FcRn binding through careful selection of mutations that maintain acidic pH affinity.
3Quantity of substance
If multiple amino acid substitutions are introduced to optimize FcγRIIa binding, then binding capacity is enhanced, but structural stability and manufacturability may be compromised
Solution Approach 1:
The patent applies partial action by introducing a limited number of strategic amino acid substitutions (typically 2-5 key residues) rather than extensive mutagenesis. This approach achieves sufficient enhancement of FcγRIIa binding capacity while minimizing disruption to overall Fc domain structure, expression efficiency, and protein stability.
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 Fc domain variants exhibit improved in vivo half-life and enhanced binding to FcγRIIa, leading to increased ADCP efficiency and prolonged drug efficacy by maintaining high affinity to FcRn under acidic conditions.
Implementation Method 1
binding and unbinding to FcRn in a pH-dependent manner
Implementation Method 2
enhanced human FcγRIIa binding capacity to induce phagocytosis of target cells and molecules
Data Source
AI summary
Provided are Fc variants having improved half-life by binding to and unbinding from FcRn in a pH-dependent manner and which have improved selective binding to Fcγ receptors. The human Fc domain variants have lower capacity to bind to immune inhibiting receptor FcγRIIb and have higher capacity to bind to immune activating receptor FcγRIIa (increased A/I ratio) than a wild-type human antibody Fc domain and conventional antibodies approved as antibody therapeutic agents, thereby having remarkably improved ADCP induction ability and having maximized half-life in blood in which excellent pH-selective FcRn binding and unbinding capacity is exhibited, and thus bind to numerous peptide drug therapeutics having a low half-life and retention time in the body to enable the peptide drug therapeutics to have an increased blood half-life and exhibit long-term drug efficacy, and can maximize the immune mechanism of therapeutic protein drugs to be effectively used as an improved antibody drug.