Chimeric Transcription Factor Variants for Drug-Regulated CAR Expression
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Solution Overview
Problem
Current genetic systems for chimeric antigen receptor (CAR) expression in cells lack precise control and safety attributes, particularly in adoptive immunotherapy, leading to potential toxicity and inefficiency in targeting malignant cells without affecting normal tissues.
Innovation Solution
Development of a genetic system that enables drug-regulated transgene expression using tamoxifen-responsive transcriptional regulators, such as TamR-tf, which allows for controlled 'ON' and 'OFF' states of CAR expression in lymphocytes, reducing toxicity and enhancing specificity through mutations in the estrogen receptor ligand binding domain and RelA transactivation domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional genetic systems are used for CAR expression, then CAR expression can be achieved, but precise control and safety attributes are lacking leading to potential toxicity
Solution Approach 1:
The patent modifies the transcriptional regulator by introducing mutations in the estrogen receptor ligand binding domain (ER-LBD) and RelA transactivation domain to alter its sensitivity to tamoxifen. These parameter changes enable the system to respond to lower drug concentrations, improving safety by reducing off-target effects while maintaining reliable CAR expression control
Solution Approach 2:
The patent introduces tamoxifen as an intermediary drug molecule that mediates between the clinician's control input and the CAR expression output. By using this external mediator, the system achieves precise temporal and spatial control over CAR expression, preventing uncontrolled toxicity while maintaining therapeutic efficacy
2Ease of operation
If conventional genetic systems are used for CAR expression, then CAR expression can be achieved, but real-time clinician control is not possible
Solution Approach 1:
The patent creates a dynamic control system where CAR expression can be turned ON and OFF in real-time through administration or withdrawal of tamoxifen. The mutated transcriptional regulator responds dynamically to changing drug concentrations, allowing clinicians to adjust therapy precisely based on patient response and side effects
Solution Approach 2:
The system enables feedback control by monitoring patient response and adjusting tamoxifen dosage accordingly. The mutated transcriptional regulator's enhanced sensitivity allows for fine-tuned response to varying drug levels, creating a controllable feedback loop between clinician input and therapeutic output
3Productivity
If high concentrations of tamoxifen are used to activate CAR expression, then CAR activation is achieved, but side effects increase
Solution Approach 1:
The patent introduces mutations in the ER-LBD (such as G521R) and RelA transactivation domain that fundamentally change the drug sensitivity parameter of the transcriptional regulator. These modifications enable the system to achieve full CAR activation at low tamoxifen concentrations (below 10 nM), thereby maintaining productivity while dramatically reducing side effects associated with high drug doses
4Measurement precision
If wild type HEA3 transcription factor is used, then drug response is achieved, but sensitivity to low drug concentrations is insufficient
Solution Approach 1:
The patent introduces specific mutations in the RelA transactivation domain (such as Q462H, L465P, or M466T) that enhance the transcriptional activity parameter. These changes allow the transcriptional regulator to produce stronger transcriptional responses at lower drug concentrations, simultaneously improving measurement precision (drug sensitivity) and productivity (transcriptional activity)
Solution Approach 2:
The patent creates a composite transcriptional regulator by fusing the mutated ER-LBD with the mutated RelA transactivation domain. This composite structure combines the enhanced drug binding specificity of the ER-LBD mutations with the enhanced transcriptional activity of the RelA mutations, achieving both high drug sensitivity and high productivity
Data Source
Figure 1A~1B
Figure 1C
Figure 1D
AI summary
Provided herein is a system for inducible expression of a chimeric antigen receptor in cells. The system comprises: a) a first nucleic acid comprising a first promoter inducible by a drug, wherein the first nucleic acid is operably linked to a first polynucleotide that encodes a chimeric antigen receptor, which comprises a ligand binding domain, a second polynucleotide, which encodes a spacer, a third polynucleotide, which encodes a transmembrane domain and a fourth polynucleotide, which encodes an intracellular signaling domain, and b) a second nucleic acid comprising a second promoter that is operably linked to a nucleic acid encoding a transcriptional activator for the first promoter inducible by drug. Methods of making such cells and methods of treatment using these cells are also provided.