Modified Diphtheria Toxin T-Cell Epitope Mutations
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Solution Overview
Problem
Current therapeutic proteins, such as monoclonal antibodies and diphtheria toxins, often induce immune responses and vascular leak syndrome (VLS) due to their immunogenicity and interaction with vascular endothelial cells, leading to adverse effects in patients.
Innovation Solution
Modified diphtheria toxins with specific amino acid residue modifications in T-cell epitopes are developed to reduce immunogenicity and binding to endothelial cells, thereby minimizing immune responses and VLS effects, while maintaining cytotoxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diphtheria toxin is used as a therapeutic agent, then cytotoxicity against cancer cells is achieved, but immune response and vascular leak syndrome occur due to immunogenicity
Solution Approach 1:
The patent extracts and modifies specific T-cell epitope regions from the diphtheria toxin sequence. By identifying and altering these epitopes (e.g., residues 7-27, 85-117, 95-127), the invention removes the harmful immunogenic components while preserving the essential cytotoxic domain responsible for cancer cell killing, thus separating the beneficial from the harmful functions.
Solution Approach 2:
The patent applies local modifications to specific regions of the toxin protein. Different domains are treated differently: the T-cell epitope regions are modified to reduce immunogenicity, while the catalytic domain maintaining cytotoxic activity is preserved. This localized approach allows the protein to have different properties in different regions - low immunogenicity where needed and high cytotoxicity where required.
2Object-affected harmful factors
If amino acid modifications are made in T-cell epitopes to reduce immunogenicity, then immune response is minimized, but cytotoxicity may be compromised
Solution Approach 1:
The patent performs preliminary identification and mapping of T-cell epitopes before making modifications. By pre-characterizing which regions are responsible for immune recognition and which are essential for cytotoxic function, the invention can strategically modify only the epitope regions while preserving the catalytic domain, ensuring cytotoxicity is maintained despite immunogenicity reduction.
Solution Approach 2:
The patent changes the amino acid sequence parameters in specific T-cell epitope regions while maintaining the overall protein structure and function. By altering residue sequences in epitope-containing domains (e.g., changing amino acids at positions 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27), the invention modifies immunogenic properties without disrupting the catalytic mechanism.
3Reliability
If diphtheria toxin binds to vascular endothelial cells, then cytotoxic effect is achieved, but vascular leak syndrome is induced
Solution Approach 1:
The patent converts the harmful binding affinity to vascular endothelial cells into a beneficial selective targeting mechanism. By modifying the toxin to reduce non-specific binding while maintaining affinity for cancer cell receptors, the invention transforms the previously harmful interaction pattern into a selective cytotoxic effect against cancer cells only, eliminating VLS while preserving therapeutic efficacy.
Data Source
AI summary
The present application relates to compositions of modified toxins exhibiting reduced immunogenicity and reduced binding to vascular endothelium or vascular endothelial cells, thereby reducing the incidence of Vascular Leak Syndrome. Also provided are polypeptide toxophores from a modified diphtheria toxin, where modifications are in at least one amino acid residue of at least one T-cell epitope. Another aspect relates to a polypeptide toxophore from a modified diphtheria toxin, where modifications are in at least one amino acid residue of at least one T-cell epitope and at least one amino acid residue of at least one VLS motif of an unmodified native diphtheria toxin. Another aspect relates to a fusion protein which comprises a modified diphtheria toxin and a non-diphtheria toxin fragment that is a cell binding portion. Another aspect relates to the use of a modified diphtheria toxin for the treatment of a malignant disease or a non-malignant disease.