Modified IgG2 Antibody Hinge for FcγRIIb Specificity
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Solution Overview
Problem
Current monoclonal antibodies targeting FcγRIIb face challenges in specificity and affinity, leading to potential side effects due to their binding to other Fcγ receptors, and existing IgG2 antibodies lack effective binding to FcγRIIb, limiting their therapeutic efficacy in allergic and inflammatory conditions.
Innovation Solution
Engineered IgG2 antibodies with specific mutations in the lower hinge sequence, such as ELLGG, EFLGG, and EFEGG, are developed to enhance binding specificity and affinity to FcγRIIb, allowing for targeted activation or inhibition of FcγRIIb in therapeutic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current monoclonal antibodies are used to target FcγRIIb, then binding to FcγRIIb is achieved, but binding to other Fcγ receptors occurs causing side effects
Solution Approach 1:
The patent applies local quality by introducing specific mutations at defined positions (232-237) in the lower hinge region of the IgG2 antibody constant domain. These localized sequence changes (such as ELLGG, EFLGG, or EFEGG) modify the binding properties specifically at this region, enhancing FcγRIIb selectivity without altering the overall antibody structure or its binding to other Fcγ receptors, thereby reducing side effects while maintaining therapeutic efficacy.
2Reliability
If existing IgG2 antibodies are used, then structural stability is maintained, but binding affinity to FcγRIIb is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence parameters in the lower hinge region of the IgG2 antibody. By changing the sequence from the wild-type to specific variants (ELLGG, EFLGG, or EFEGG at positions 232-237), the binding affinity to FcγRIIb is enhanced while maintaining the IgG2 structural framework. This parameter modification directly improves therapeutic efficacy by enabling effective FcγRIIb activation or inhibition.
3Measurement precision
If mutations are introduced to enhance FcγRIIb binding, then binding specificity improves, but antibody structure complexity increases
Solution Approach 1:
The patent applies segmentation by focusing mutations exclusively on a specific segment of the antibody structure - the lower hinge region (positions 232-237) of the constant domain. This segmented approach allows the rest of the antibody to maintain its native IgG2 structure and function, while only the critical binding segment is modified. This minimizes overall structural complexity while achieving enhanced FcγRIIb binding specificity.
Data Source
AI summary
Immunotherapeutic proteins comprising at least one heavy chain polypeptide derived from an IgG2 antibody are disclosed, wherein the heavy chain polypeptide comprises at least constant heavy domains 2 and 3 (CH2 and CH3) and the lower hinge, and the sequence of the lower hinge comprises a mutation enabling the immunotherapeutic protein to bind to and/or activate FcγRIIb. The immunotherapeutic protein is suitable for use in methods of treating diseases or conditions wherein, for example, the activation of FcγRIIb (ie for recruitment of the inhibitory functions of FcγRIIb) is beneficial, such as allergic diseases.