ADA-Response Assay Using Germline-Replaced Fab Fragments
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Solution Overview
Problem
Current methods for characterizing immunogenicity responses to therapeutic antibodies, especially for smaller biotherapeutics like scFv and Fab fragments, are limited by their inability to easily distinguish between anti-drug antibodies directed against different target-binding paratopes and the constant part, leading to potential false negative results and reduced reliability.
Innovation Solution
A molecular engineering approach combined with a domain detection assay, where individual antigen-binding regions are replaced with human germline sequences, allowing for the discrimination between anti-drug antibodies directed against target-binding paratopes and the constant part of therapeutic antibodies, thereby improving the characterization of immunogenicity responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If classical domain competition and domain detection assays are used for ADA characterization, then the method is applicable to large protein molecules like IgG, but it becomes difficult to apply to smaller biotherapeutics like scFv and Fab fragments due to their inability to be easily cleaved into subdomains
Solution Approach 1:
The patent applies segmentation by dividing the ADA characterization process into multiple specific assays targeting different domains (Fc domain assay, VH domain assay, VL domain assay). This allows comprehensive characterization without requiring physical cleavage of the therapeutic molecule, thus resolving the contradiction between versatility and ease of manufacture.
Solution Approach 2:
The patent uses domain-specific capture reagents (anti-Fc antibodies, anti-VH antibodies, anti-VL antibodies) as intermediaries to detect ADAs against specific domains. These intermediaries enable domain-specific detection without requiring cleavage of the therapeutic molecule, thus resolving the contradiction between applicability to different biotherapeutic sizes and ease of domain separation.
2Reliability
If competitive/inhibition-based ADA detection methods are used, then the assay can detect mixed-affinity and mixed-paratope ADA responses, but false negative results may occur due to interference from non-neutralizing ADAs
Solution Approach 1:
The patent segments the ADA detection into multiple domain-specific assays (Fc domain assay, VH domain assay, VL domain assay). Each assay uses a specific capture reagent that binds only to its target domain, preventing interference from non-neutralizing ADAs against other domains. This segmentation eliminates false negatives while maintaining reliable detection.
Solution Approach 2:
The patent applies local quality by designing each assay with a specific capture reagent that has high specificity for its target domain. The Fc domain assay uses anti-Fc antibodies, the VH domain assay uses anti-VH antibodies, and the VL domain assay uses anti-VL antibodies. This localized specificity ensures that each assay detects only relevant ADAs, improving reliability without excessive complexity.
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 method provides a reliable and sensitive characterization of immunogenicity responses, reducing false negative results and enhancing the understanding of preclinical immunogenicity, particularly for smaller therapeutic antibodies, by directly capturing variants with replaced hypervariable regions, thus improving the assessment of therapeutic antibodies' immunogenicity profiles.
Implementation Method 1
incubating a sample, which comprises serum and an antibody specifically binding to a therapeutic antibody, with at least a Fab fragment of the therapeutic antibody
Data Source
AI summary
Herein is reported a method for determining the epitope of an antibody specifically binding to a therapeutic antibody comprising the steps of a) incubating a sample, which comprises serum and the antibody specifically binding to a therapeutic antibody, separately with i) at least a Fab fragment of the therapeutic antibody, and ii) at least a Fab fragments of the therapeutic antibody in which the HVRs forming a paratope have been replaced with germline sequences, and detecting the binding or non-binding of the antibody specifically binding to a therapeutic antibody to the at least a Fab fragment in any of i) to ii), and b) determining the epitope of the antibody specifically binding to a therapeutic antibody to be in the at least one HVR that has been replaced in ii) if binding is detected in i) and non-binding is detected in ii).