Modified Pseudomonas Exotoxin A with Furin Cleavage Sequence
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Solution Overview
Problem
Current PE-based immunotoxins face limitations due to dose-limiting toxicities and high immunogenicity, restricting their therapeutic effectiveness, especially in treating solid tumors where repeated doses are needed but often rendered ineffective by patient antibody responses.
Innovation Solution
Development of mutated Pseudomonas exotoxin A (PE) with a modified amino acid sequence and structure, specifically a furin cleavage sequence and domain III, which reduces non-specific toxicity and immunogenicity, allowing for higher doses and repeated administrations without adverse reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PE-based immunotoxins are used to treat malignancies, then anti-tumor activity is achieved, but dose-limiting toxicities and high immunogenicity restrict therapeutic effectiveness
Solution Approach 1:
The patent extracts and removes specific harmful regions (domains) from the PE toxin structure. Specifically, it deletes domain I and portions of domain II from the full-length PE, retaining only the essential cytotoxic domain III and the furin cleavage sequence. This extraction eliminates the harmful non-specific toxicity and immunogenic epitopes while preserving the essential anti-tumor activity through the retained domain III.
Solution Approach 2:
The patent fundamentally changes the structural parameters of the PE toxin by creating a truncated version with modified amino acid sequence. The mutation creates a new PE variant (PEmut) with altered molecular weight, reduced immunogenicity, and lowered non-specific toxicity. This parameter change allows the toxin to maintain therapeutic effectiveness while reducing harmful effects.
2Productivity
If PE-based immunotoxins are administered multiple times, then repeated treatment is possible, but patient antibodies render subsequent doses ineffective
Solution Approach 1:
The patent removes the immunogenic domain I and portions of domain II that serve as targets for neutralizing antibodies. By retaining only domain III and the furin cleavage sequence, the modified PE toxin eliminates the epitopes that trigger antibody formation, thereby enabling multiple administrations without loss of efficacy.
Solution Approach 2:
The patent creates a streamlined, simplified PE variant that is designed to be metabolically short-lived and rapidly cleared from the system. This short half-life prevents sustained antibody formation and allows for repeated dosing schedules without accumulating immunogenicity, effectively treating solid tumors with multiple administrations.
3Object-affected harmful factors
If truncated PE forms like PE38 are used, then non-specific toxicity is reduced, but dose-limiting toxicities still restrict therapeutic effect
Solution Approach 1:
The patent extracts and removes the remaining harmful elements from PE38 by deleting domain II entirely and retaining only domain III with the furin cleavage sequence. This complete extraction of harmful domains eliminates the residual non-specific toxicity of PE38 while preserving the essential cytotoxic activity needed for therapeutic effect.
Solution Approach 2:
The patent creates a new PE variant with fundamentally altered structural parameters - removing domains I and II, retaining only domain III. This parameter change results in a molecule with reduced molecular weight, eliminated non-specific toxicity, and preserved therapeutic activity, overcoming the limitations of PE38.
Data Source
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AI summary
The invention provides mutated, cytotoxic forms of Pseudomonas exotoxin A (PE) comprising a furin cleavage sequence conjugated or fused directly to residues 395-613 of PE or variants of that sequence. These minimal forms of PE are smaller than previous cytotoxic forms of PE, reduce non-specific toxicity, and reduce immunogenicity due to domain II or domain Ib of PE. The invention further provides nucleic acids encoding said PEs, chimeric molecules containing them, and methods of use thereof.