CLDN18.2-CD3 Bispecific Antibodies for FcγR-Independent T-Cell Killing
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Solution Overview
Problem
Current cancer treatments for gastric and esophageal cancers, particularly those targeting CLDN18.2, face limitations such as low efficacy due to broad distribution of low-affinity Fc receptor variants and competition with patient IgGs, leading to high antibody doses and negative signaling, and lack of specificity in existing antibody-based therapies.
Innovation Solution
Development of bispecific binding agents that specifically target CLDN18.2 and CD3, comprising polypeptide chains with variable regions and constant regions to form a complex that induces cytotoxic T cell activation and lysis of cancer cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional IgG1 antibodies are used to target CLDN18.2, then they can engage the cellular immune system via Fc domain interaction with Fcγ receptors, but they face broad distribution of low-affinity Fc receptor variants and competition with patient IgGs leading to reduced efficacy
Solution Approach 1:
The patent extracts the Fc domain from the antibody structure to create antibody fragments (Fab, scFv, Fv) that lack FcγR binding capability. This removes the harmful interaction with Fc receptors while preserving the antigen-binding function, thereby eliminating the problem of broad Fc receptor distribution and IgG competition
Solution Approach 2:
The patent introduces T cell engagement as an intermediary mechanism to achieve cytotoxicity. Instead of relying on FcγR-mediated ADCC, the antibody fragments redirect T cells to attack target cells through CD3 or other T cell surface antigen interactions, providing an alternative pathway that avoids Fc receptor limitations
2Reliability
If high doses of antibodies are administered to overcome competition with patient IgGs, then target coverage may be improved, but the treatment complexity and potential side effects increase
Solution Approach 1:
The patent employs antibody fragments that are smaller and can be administered at lower doses compared to full IgG1 antibodies. These fragments function effectively without requiring high dosages to overcome IgG competition, simplifying the treatment regimen and reducing administrative complexity
3Reliability
If FcγRIIb interaction is utilized for antibody function, then immune engagement occurs, but negative signaling is induced that decreases therapeutic efficacy
Solution Approach 1:
The patent removes the Fc domain from the antibody structure, creating fragments that cannot bind to FcγRIIb or other Fcγ receptors. This extraction eliminates the source of negative signaling while preserving the ability to engage T cells through alternative mechanisms such as CD3 binding
Solution Approach 2:
The patent converts the limitation of lacking Fc domain functionality into a benefit by designing T cell redirecting mechanisms that are independent of FcγR interactions. The absence of Fc domain prevents harmful FcγRIIb binding while the engineered T cell engagement provides beneficial cytotoxicity
Data Source
AI summary
The present invention provides binding agents comprising at least two binding domains, wherein a first binding domain has specificity for CLDN18.2 and a second binding domain has specificity for CD3, and methods of using these binding agents or nucleic acids encoding therefor for treating cancer.