Bispecific Antibody Complex Detection Under Binding Equilibrium
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Solution Overview
Problem
Existing methods struggle to quantitatively evaluate low-affinity antigen-antibody complexes due to their low concentration and susceptibility to binding equilibrium shifts, making it difficult to detect and measure weakly bound complexes like those formed by bispecific antibodies.
Innovation Solution
A method involving a first and second binding entity to bind to a complex under conditions maintaining binding equilibrium, allowing for the detection and quantification of complexes with KD values of 1 nM or greater, using techniques like KinExA or Gyrolab without labeling or immobilization on a solid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing techniques such as SEC and AUC are used to evaluate antigen-antibody complexes, then qualitative evaluation can be performed, but quantitative evaluation is difficult due to low sensitivity and significant influence of binding equilibrium shifts
Solution Approach 1:
The invention changes the detection parameter from measuring complex concentration directly (which is difficult for low-concentration complexes) to measuring the dissociation constant KD through binding equilibrium analysis. By measuring free antigen concentration at different antibody concentrations and calculating KD values, the method enables quantitative evaluation of low-affinity complexes that were previously undetectable.
Solution Approach 2:
The invention introduces free antigen concentration as an intermediary measurement parameter. Instead of directly measuring the complex (which is difficult due to low concentration and equilibrium shifts), the method measures free antigen concentration and uses it to calculate complex formation, thereby enabling quantitative evaluation of low-affinity antigen-antibody complexes.
2Measurement precision
If measurement is performed under conditions that allow complex formation, then binding equilibrium shifts significantly, but if measurement is performed quickly, then detection sensitivity is insufficient
Solution Approach 1:
The invention uses a feedback approach by measuring free antigen concentration at multiple antibody concentrations and using this data to calculate the dissociation constant KD. This feedback loop allows determination of binding characteristics without requiring the system to reach or maintain equilibrium during detection, thereby resolving the contradiction between detection sensitivity and equilibrium stability.
Solution Approach 2:
The invention performs preliminary measurements of free antigen concentration at various antibody concentrations before calculating the final KD value. This preliminary action allows the system to capture binding information without requiring the complex to remain in equilibrium state during the actual detection, thus maintaining both sensitivity and equilibrium 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
Enables sensitive detection and quantitative determination of weak-affinity complexes, such as ternary complexes formed by bispecific antibodies, in biological samples while minimizing dissociation and equilibrium shifts.
Implementation Method 1
A method involving a first and second binding entity to bind to a complex under conditions maintaining binding equilibrium, allowing for the detection and quantification of complexes with KD values of 1 nM or greater
Data Source
AI summary
The present invention provides methods for detecting a complex with low affinity, under conditions in which the binding equilibrium of the complex is substantially maintained, and methods for measuring the concentration and/or amount of the complex. The invention also provides methods for evaluating the kinetics of a complex and methods for deciding on a therapeutic method that uses a pharmaceutical agent, based on the concentration and/or amount of the complex determined by the above-mentioned measurement method.