Modified NKG2D Ligands for Selective CAR Activation
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Solution Overview
Problem
Current CAR-T and CAR-NK cell therapies face challenges such as severe systemic toxicities, antigen escape, and inefficiencies in targeting specific cells, particularly due to the activation of CARs by natural NKG2D ligands, leading to toxicity and limited control over therapeutic effects.
Innovation Solution
Development of modified, non-natural α1-α2 domains of NKG2D ligands with attached heterologous molecules that selectively bind to non-natural NKG2D receptors on engineered cells, creating bispecific molecules that only activate CARs in the presence of specific targets, thereby controlling activation and reducing off-target toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural NKG2D ligands are used to activate CARs, then CAR cells can recognize and attack target cells, but severe systemic toxicities occur due to lack of specificity
Solution Approach 1:
The ligand is divided into separate functional domains: the NKG2D-binding α1-α2 domain is separated from the heterologous targeting molecule (such as an antibody fragment). This segmentation allows the CAR to recognize the ligand structure while the heterologous domain provides specific target binding, ensuring that activation only occurs when both the NKG2D receptor and the specific target antigen are present on the same cell surface.
Solution Approach 2:
The ligand is constructed as a composite molecule combining the NKG2D-binding α1-α2 domain with a heterologous targeting polypeptide (such as a scFv antibody fragment). This composite structure enables dual recognition: the NKG2D receptor binds the α1-α2 domain while the heterologous domain binds the specific target antigen, providing both activation signal and target specificity to prevent off-target toxicity.
2Ease of operation
If CARs are activated by natural ligands, then therapeutic effect is achieved, but control over activation timing and location is limited
Solution Approach 1:
The heterologous targeting molecule (such as a scFv antibody fragment) acts as an intermediary that bridges the NKG2D receptor and the specific target antigen. This intermediary ensures that CAR activation only occurs when the ligand simultaneously engages both the NKG2D receptor and the target antigen, providing precise spatial and temporal control over activation at the target site while preventing premature or off-target activation.
3Reliability
If modified ligands with heterologous molecules are used, then targeting specificity is improved, but molecule complexity increases
Solution Approach 1:
The NKG2D-binding α1-α2 domain and the heterologous targeting molecule (such as a scFv) are merged into a single polypeptide chain through genetic fusion. This merging creates a unified ligand structure that presents both functional domains in appropriate spatial orientation, enabling simultaneous binding to NKG2D receptor and target antigen while simplifying production through single-gene expression compared to using separate molecules.
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 approach enhances the specificity and efficacy of CAR-T and CAR-NK cell therapies by allowing controlled activation and reducing systemic toxicity, enabling more precise targeting of malignant cells or virus-infected cells while minimizing harm to healthy tissues.
Implementation Method 1
The ligand has an attached heterologous molecule that selectively binds an HIV protein present on the surface of a cell infected by HIV, wherein the modified ligand with its heterologous molecule can selectively bind to a modified, non-natural NKG2D receptor of a CAR-cell
Data Source
AI summary
This application relates generally to the production of modified, non-natural α1-α2 domains of NKG2D ligands with attached polypeptides having specific target-binding properties, for example, antibodies or variable fragments of antibodies, that are selectively delivered to Chimeric Antigen Receptors (CARs) comprised of modified, non-natural NKG2D receptors on engineered mammalian cells. The targeting of surface-expressed molecules includes those of virus-infected cells that can then be attacked and ablated by engineered cells of the immunity system expressing CARs cognate to the modified, non-natural α1-α2 domains of NKG2D ligands with attached polypeptides.