AAV GLA Expression Constructs for Sustained Fabry Enzyme Activity
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Solution Overview
Problem
Current enzyme replacement therapies for Fabry disease, such as ERT, require frequent infusions and can lead to infusion-related reactions and the development of neutralizing antibodies, failing to effectively clear substrate from organs and halt disease progression.
Innovation Solution
A method of expressing α-galactosidase A (α-Gal A) protein in cells using a mutated WPRE sequence and a GLA transgene, delivered via an AAV viral vector, to achieve sustained enzyme activity in the liver and other organs, potentially eliminating the need for frequent infusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If enzyme replacement therapy (ERT) using recombinant α-Gal A is administered, then the enzyme can be delivered to secondary tissues via mannose-6-phosphate receptor-mediated uptake, but the short half-life (approximately 1 hour in plasma) necessitates a lifetime of frequent infusions
Solution Approach 1:
The patent applies preliminary action by modifying the enzyme's glycosylation pattern in advance (using α1-3-galactosyltransferase to add galactose residues to N-acetylglucosamine) before administration. This pre-modification enables the enzyme to bind with high affinity to the asialoglycoprotein receptor, which naturally clears proteins from the bloodstream, thereby achieving prolonged circulation half-life (up to 8 days in mice) without requiring frequent subsequent infusions
2Reliability
If recombinant α-Gal A is administered frequently, then enzyme activity can be maintained, but infusion-related reactions occur in a significant proportion of patients, some of which are severe
Solution Approach 1:
The patent changes the biochemical parameters of the enzyme by modifying its glycosylation structure (adding terminal galactose residues). This parameter change alters the enzyme's interaction with cellular receptors, enabling prolonged circulation and reduced clearance rate. Consequently, less frequent administration is needed, reducing the cumulative exposure to infusion-related reactions while maintaining reliable enzyme activity through the extended half-life
3Reliability
If long-term ERT is administered, then substrate accumulation can be managed, but patients eventually generate antibodies to the recombinant enzyme, which may impact the activity of the ERT enzyme
Solution Approach 1:
The patent changes the immunogenic parameters of the enzyme by modifying its glycosylation pattern to include terminal galactose residues. This structural modification creates a novel enzyme variant that is less recognizable to the patient's immune system, thereby reducing the formation of neutralizing antibodies. The modified enzyme maintains its catalytic activity for substrate clearance while exhibiting reduced immunogenicity, allowing for longer-term effective treatment
4Loss of time
If recombinant α-Gal A with longer half-lives is developed, then administration frequency can be reduced, but α-Gal A levels will still fluctuate significantly over time and immune responses may still occur
Solution Approach 1:
The patent applies preliminary action by pre-modifying the enzyme's glycosylation structure to enable high-affinity binding to the asialoglycoprotein receptor. This pre-engineering ensures that the enzyme is cleared from the bloodstream at a controlled, extended rate rather than being rapidly eliminated. The result is more stable enzyme levels over time with reduced fluctuation, while also reducing administration frequency due to the prolonged half-life of up to 8 days in preclinical models
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 method results in prolonged α-Gal A protein expression, reducing glycospingolipid levels by up to 80% and achieving activity levels 100- to 1,500-fold higher than normal, effectively managing Fabry disease symptoms without the need for continuous treatment.
Implementation Method 1
administering an expression construct comprising a mutated WPRE sequence, optionally a mut6 mutated WRPE sequence, and a GLA transgene encoding at least one α-Gal A protein to the cell such that the α-Gal A protein is expressed in the cell
Implementation Method 2
α-Galactosidase is an enzyme that catalyzes hydrolysis of the terminal α-galactosyl moieties of oligosaccharides and polysaccharides
Implementation Method 3
an expression construct comprising a mutated WPRE sequence, optionally a mut6 mutated WRPE sequence, and a GLA transgene
Data Source
AI summary
The present disclosure provides expression constructs comprising a GLA transgene encoding the at least one α-Gal A protein for use in expressing α-Gal A proteins and preventing, inhibiting or treating Fabry disease or one or more symptoms associated with Fabry disease.