CTLA4 Mutant Molecules for Nephrotoxicity-Free Immunosuppression
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Solution Overview
Problem
Current immunosuppressive regimens for renal transplantation, particularly calcineurin inhibitors, are nephrotoxic and contribute to long-term allograft loss and subject death, with no approved alternatives that can replace them without toxicities, especially for patients at higher risk of graft loss.
Innovation Solution
Development of a CTLA4 mutant molecule with enhanced binding avidity to CD80 and CD86, specifically L104EA29YIg and L104EIg, which are administered in a regimen targeting serum trough concentrations to inhibit T-cell activation and function, reducing the need for calcineurin inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calcineurin inhibitors are used for immunosuppression in graft transplantation, then T-cell activation is blocked, but nephrotoxicity and cardiovascular risks occur
Solution Approach 1:
The patent applies parameter changes by modifying the binding affinity parameter of CTLA4 to CD80/CD86 through amino acid mutations (L104E, A29Y). These mutations increase the dissociation constant (Kd) from nanomolar to picomolar range, enhancing binding strength by 10-100 fold. This parameter change allows the use of lower drug doses while achieving the same immunosuppressive effect, thereby reducing nephrotoxicity associated with higher doses of conventional agents
Solution Approach 2:
The patent uses soluble CTLA4Ig fusion protein as an intermediary molecule that blocks the interaction between CD80/CD86 and CD28 on T-cells. This intermediary approach selectively inhibits T-cell activation through the CTLA4-CD80/86 pathway without requiring calcineurin inhibitors, thereby achieving immunosuppression while avoiding their nephrotoxic side effects
2Duration of action of stationary object
If current immunosuppressive regimens are used to prevent graft rejection, then allograft survival is maintained, but long-term allograft loss and subject death increase
Solution Approach 1:
The patent changes the pharmacokinetic parameters of the immunosuppressive agent by using a high-affinity binder with picomolar Kd values. This allows for less frequent dosing (every 2-4 weeks instead of daily) while maintaining therapeutic levels, improving patient compliance and long-term graft survival without the cumulative toxicity of conventional regimens
Solution Approach 2:
The patent achieves continuous immunosuppressive action through the prolonged half-life of the high-affinity CTLA4Ig fusion protein. The extremely tight binding to CD80/CD86 ensures continuous blockade of costimulatory signals throughout the dosing interval, providing uninterrupted protection against graft rejection while minimizing drug-related toxicity over the long term
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 CTLA4 mutant molecules effectively inhibit T-cell activation and cytokine production, prolonging allograft survival and improving renal function without the toxicities associated with calcineurin inhibitors, offering a safer immunosuppressive option for both low and high-risk patients.
Implementation Method 1
CTLA4 mutant molecules with increased binding avidity to CD80 and CD86
Data Source
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AI summary
The present invention provides use of soluble CTLA4 mutant molecules which bind with greater avidity to the CD80 and/or CD86 antigen than wild type CTLA4 or non-mutated CTLA4Ig in the treatment of immune disorders associated with graft transplantation.