Mutated ARSA Enzyme Stability and BBB Transcytosis
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Solution Overview
Problem
Current therapeutic approaches for Metachromatic Leukodystrophy (MLD), such as enzyme replacement therapy and gene therapy, face challenges in achieving sufficient enzyme activity in the central nervous system due to the blood-brain barrier and the need for high doses, which can lead to adverse effects and limited efficacy.
Innovation Solution
A mutated arylsulfatase A (ARSA) enzyme with increased protein stability, specifically through mutations around amino acid 424, is developed to enhance protein half-life and activity, allowing for lower enzyme concentrations to maintain effectiveness and reduce adverse reactions, combined with a C-terminal apoE-II tag for improved transcytosis across the blood-brain barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high doses of wild-type ARSA are administered to overcome the blood-brain barrier, then sufficient enzyme activity in the central nervous system is achieved, but adverse effects increase and treatment safety decreases
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of ARSA (specifically at position 424 and surrounding residues) to alter the protein's physical-chemical properties, resulting in increased stability and half-life. This allows the enzyme to maintain effective concentrations in the central nervous system at lower administered doses, thereby reducing adverse effects while ensuring therapeutic efficacy.
Solution Approach 2:
The patent creates a composite therapeutic approach by combining the mutated ARSA enzyme with a C-terminal apoE-II tag. This fusion protein combines the catalytic activity of ARSA with the blood-brain barrier transcytosis enhancement capability of apoE-II, enabling effective CNS delivery at lower doses and improving the therapeutic index.
2Productivity
If wild-type ARSA is administered to treat MLD, then sulfatide degradation is achieved, but the enzyme half-life is insufficient leading to frequent administrations and reduced treatment efficacy
Solution Approach 1:
The patent modifies key parameters of the ARSA protein by introducing specific amino acid mutations (particularly at position 424) that enhance protein stability and resistance to degradation. These parameter changes result in a 2-fold to 28-fold increase in enzyme half-life, allowing the enzyme to maintain productive sulfatide degradation activity for extended periods and reducing the frequency of administrations required.
3Reliability
If high concentrations of ARSA are used to ensure therapeutic effect, then enzyme activity is sufficient, but the complexity of dosing regimens increases and treatment safety decreases
Solution Approach 1:
By changing the stability parameter of ARSA through amino acid mutations, the patent extends the enzyme's functional half-life significantly. This parameter change allows for less frequent administrations (e.g., every 2-4 weeks instead of weekly), simplifying the dosing regimen while maintaining reliable therapeutic enzyme activity levels in the central nervous system.
4Speed
If wild-type ARSA is administered to cross the blood-brain barrier, then some enzyme activity reaches the CNS, but the efficiency is insufficient requiring very high doses
Solution Approach 1:
The patent employs a composite protein structure by fusing ARSA with the apoE-II peptide tag at the C-terminus. This composite construction leverages the known ability of apoE-II to interact with receptor-mediated transcytosis pathways across the blood-brain barrier, thereby enhancing the transport efficiency of the therapeutic ARSA enzyme into the CNS and reducing the required dosage.
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 mutated ARSA enzyme demonstrates a 2-fold to 28-fold increase in protein half-life and enhanced activity, achieving significant sulfatide degradation and reduced sulfatide storage in the brain and spinal cord with lower doses, thereby improving treatment efficacy and safety.
Implementation Method 1
ARSA hydrolyzes sulfatide to galactosylceramide and sulfate
Data Source
AI summary
The invention is based on the introduction of mutations into the amino acid sequence of human Arylsulfatase A (ASA or ARSA) in order to increase protein stability. The invention introduces amino acid mutations, such as deletions, substitutions or additions, into the C-terminal part of the human ARSA enzyme, in particular at a position around or at amino acid 424, which result in a sequence that does not comprise E424. Provided are further nucleic acids and vectors for the expression of the mutated ARSA of the invention, recombinant cells and pharmaceutical composition comprising the mutated ARSA, as well as its use in the treatment of diseases that are characterized by a reduced activity of endogenous ARSA.