Multimeric CAR Detection Reagent via SPAAC Chemistry
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Solution Overview
Problem
Current methods for detecting chimeric antigen receptor (CAR) cells are inadequate due to variability in CAR expression levels and the need for sensitive and specific detection in complex biological samples, where CAR cells represent a small fraction of total cells, leading to challenges in developing reliable and flexible detection reagents.
Innovation Solution
A detection reagent is developed using a specific multimerization strategy of an engineered peptide with high affinity for the anti-CD20 antigen receptor, conjugated to a detection moiety via SPAAC chemistry, allowing for the formation of modified detection moieties that bind to CAR cells, enabling sensitive and specific detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection reagents are used for CAR cells, then the detection method is simple, but the sensitivity and brightness are insufficient to detect CAR cells representing only 0.01-0.5% of total cells in complex biological samples
Solution Approach 1:
The detection reagent is segmented into multiple functional components: a multimeric polypeptide component (X-S)m-D consisting of multiple antigen-binding domains, a spacer component (S), and a detection moiety (D). This segmentation allows each component to perform its specific function optimally while achieving high overall sensitivity through the multimeric structure that amplifies signal binding to the low-abundance CAR cells.
Solution Approach 2:
The invention creates a composite detection reagent by chemically conjugating the polypeptide component (X) with the detection moiety (D) through the spacer (S). This composite structure combines the high-affinity binding capability of the engineered polypeptide with the signal-amplifying properties of the multimeric architecture and detection moiety, achieving both high sensitivity and specificity in detecting rare CAR cells within complex biological samples.
2Measurement precision
If detection reagents are designed for high sensitivity to detect rare CAR cells, then detection brightness improves, but unspecific staining and background staining increase
Solution Approach 1:
The spacer component (S) in the reagent structure (X-S)m-D provides local quality by creating a physical separation between the detection moiety and the cell surface. This localized spacing allows the detection moiety to extend away from the cell membrane, reducing non-specific interactions and background staining while maintaining high-affinity binding through the multimeric polypeptide component, thereby achieving high detection brightness with minimized background interference.
3Adaptability or versatility
If CAR expression levels are highly variable across different cell types and passages, then detection flexibility is needed, but conventional reagents lack adaptability to maintain consistent detection across varying expression levels
Solution Approach 1:
The detection reagent is designed with universal applicability through its multimeric polypeptide structure (X-S)m-D that can bind to various CAR variants with high affinity. The engineered polypeptide component (X) with multiple antigen-binding domains provides multi-functional binding capability that adapts to different CAR expression levels and cell types, while the standardized detection moiety (D) ensures consistent signal output, thereby maintaining detection reliability across variable CAR expression conditions.
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 method enhances the sensitivity and specificity of CAR cell detection, improving the ability to identify and quantify CAR cells in complex samples by increasing the brightness of the detection signal while minimizing background staining, thus aiding in the analysis and therapeutic applications of CAR therapies.
Implementation Method 1
X is a polypeptide comprising 10 to 80 amino acids and a N3 group wherein X binds to the antigen binding domain of a chimeric antigen receptor of a cell
Implementation Method 2
conjugation to a detection moiety (e.g. fluorescent PE protein) via SPAAC chemistry using DBCO activated PE and N3-terminated CD20 peptide
Data Source
AI summary
The invention is directed to a method for preparing a detection reagent for CAR expressing cells according to general formula (I)(X-S)m-D (I)wherein D is a detection moiety, S a spacer unit and X a polypeptide comprising 10 to 80 amino acids and a N3 group, which binds to the antigen binding domain of a chimeric antigen receptor of a cell and m=4-200, characterized in reacting p detection moieties D with a spacer S according to general formula (II)wherein R is a leaving group, q=1 to 5, and n=4 to 200 and p is 4-250thereby forming modified detection moiety Sp-D and reacting the modified detection moiety Sp-D with a plurality of polypeptides X to yield (X-S)m-D.