FOXP3-Locus Engineered Treg Cells for Controlled CAR Expression
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Solution Overview
Problem
Existing Treg cell therapies are polyclonal and may not effectively control autoimmune diseases due to insufficient specificity and immunosuppressive functions, and increasing Treg numbers alone is not sufficient for disease control.
Innovation Solution
Genetically engineered regulatory T cells with a heterologous sequence in the FOXP3 locus, under the control of the FOXP3 promoter, expressing a transgene such as a chimeric antigen receptor (CAR) or cytokine, ensuring active expression only when the cell maintains its Treg phenotype.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Treg numbers are increased through adoptive cell therapy, then the quantity of immunosuppressive cells is improved, but the specificity and effectiveness of disease control deteriorates due to polyclonal nature
Solution Approach 1:
The patent applies local quality by making Treg cells antigen-specific through genetic engineering. The transgene expresses antigen-specific receptors (TCR or CAR) that are localized to specific Treg cell populations, enabling them to target particular autoantigens or alloantigens. This creates a heterogeneous population where each cell type has specialized function for specific antigens, rather than a uniform polyclonal population.
Solution Approach 2:
The patent changes the genetic parameters of Treg cells by introducing heterologous sequences into the FOXP3 locus. This genetic modification alters the expression profile of Treg cells, enabling them to express both FOXP3 (maintaining regulatory function) and antigen-specific receptors (providing specificity). The parameter change transforms polyclonal Tregs into antigen-specific engineered Tregs with enhanced therapeutic reliability.
2Productivity
If transgene expression is constitutively active, then the production of immunosuppressive functions is improved, but the safety and controllability deteriorates due to loss of FOXP3-dependent regulation
Solution Approach 1:
The patent merges the FOXP3 promoter regulatory element with the transgene coding sequence into a single integrated construct. The transgene is positioned downstream of the FOXP3 promoter, creating a fused regulatory-coding unit. This merging ensures that transgene expression is coupled with FOXP3 expression, so that when FOXP3 is active in Treg cells, the transgene is simultaneously activated, providing both immunosuppressive function and safety through coordinated regulation.
Solution Approach 2:
The patent implements feedback control by using the FOXP3 promoter to regulate transgene expression. Since FOXP3 is the master transcription factor that defines Treg cell identity and function, its promoter acts as a feedback mechanism: when Treg cells maintain their regulatory phenotype (high FOXP3 expression), the transgene is actively expressed; when Treg cells lose their phenotype (low FOXP3 expression), transgene expression automatically decreases. This creates a self-regulating system that enhances safety and controllability.
Data Source
AI summary
The present disclosure provides mammalian cells such as regulatory T cells containing a transgene in the FOXP3 genomic locus. Also provided are methods of generating the cells and methods of using the cells to treat patients in need of immunosuppression.