Chimeric Antigen Receptor Screening Reducing Self-Antigen Reactivity
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Solution Overview
Problem
Current methods for screening chimeric antigen receptors (CARs) reactive to a target antigen often produce false positive signals due to high levels of non-specific binding, masking the signal from the target antigen binding, and fail to effectively select out CARs reactive to self-antigens, which poses safety risks and reduces therapeutic efficacy.
Innovation Solution
A method involving a series of steps to screen a library of cells, including contacting cells with a target antigen, selecting cells for specificity, and then differentiating between cells expressing activation markers to isolate those with low background binding, thereby identifying CARs with high antigen binding specificity and reduced reactivity to self-antigens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current screening methods are used to identify CARs reactive to target antigen, then CARs with high target antigen binding can be identified, but false positive signals occur due to high levels of non-specific binding to self-antigens
Solution Approach 1:
The screening process is divided into distinct sequential steps: initial binding selection followed by separate negative selection against self-antigens. This segmentation allows independent optimization of each selection criterion, enabling precise identification of CARs with specific target antigen binding while eliminating those with non-specific self-antigen reactivity.
Solution Approach 2:
Self-antigens are introduced as intermediary molecules during the negative selection step. These intermediaries enable the indirect identification and removal of CARs that bind non-specifically to self-antigens, thereby purifying the pool of CARs with genuine target antigen specificity without directly measuring false positive binding events.
2Strength
If screening focuses on high target antigen reactivity, then potent CARs are identified, but CARs with lower reactivity that may still be therapeutically useful are eliminated
Solution Approach 1:
The negative selection step is applied partially rather than completely eliminating all bound CARs. By controlling the stringency and duration of negative selection, CARs with varying levels of target antigen reactivity are preserved as long as they meet the minimum specificity threshold, thereby maintaining a diverse pool with different therapeutic potentials.
Solution Approach 2:
The screening conditions are optimized to allow a range of binding affinities. Parameters such as antigen concentration, incubation time, and selection stringency are adjusted to preserve CARs with lower but still therapeutically relevant reactivity, expanding the versatility of identified candidates beyond just high-affinity binders.
3Device complexity
If CARs with high self-antigen reactivity are not removed, then screening is simpler, but safety risks increase due to potential off-target effects
Solution Approach 1:
Negative selection against self-antigens is performed as a preliminary step before functional assays and therapeutic development. This preliminary action proactively identifies and removes potentially unsafe CARs early in the screening process, preventing progression of problematic candidates and ensuring safety without requiring complex safety testing later.
Solution Approach 2:
The potential harm of non-specific self-antigen binding is converted into a beneficial selection criterion. By intentionally introducing self-antigens in the negative selection step, the harmful non-specific binding behavior is transformed into a detectable signal that enables automatic identification and removal of unsafe CARs, turning a safety risk into a quality control mechanism.
Data Source
AI summary
Described herein are methods of generating a library of cells expressing a plurality of polypeptides or recombinant polypeptides activated by an antigen and methods of panning said library of cells against a target antigen. The methods can be utilized for screening a library of chimeric antigen receptors reactive to a target antigen.