AAV Gene Therapy Composition for GSD III cDNA Size Constraints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for a minimally invasive, definitive therapy to address the underlying cause and sequelae of glycogen storage disease type III (GSD III), as current treatments do not prevent disease progression and existing gene therapy vectors like AAV are limited by packaging constraints.
Innovation Solution
Development of CpG-depleted and codon-optimized nucleic acid sequences encoding microbial or truncated human glycogen debranching enzymes, delivered via AAV vectors with dual promoters, to prevent and degrade glycogen accumulation in tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the human glycogen debranching enzyme cDNA is used for gene therapy, then the therapeutic effect is achieved, but the packaging limit of AAV vectors is exceeded
Solution Approach 1:
The patent extracts only the essential functional domain of the glycogen debranching enzyme (the debranching activity) while removing non-essential portions of the full-length cDNA. This creates a truncated enzyme that retains therapeutic function but fits within AAV packaging limits. The extracted functional core is then delivered via AAV vector to achieve gene therapy without exceeding the 4.7 kb packaging constraint.
Solution Approach 2:
The glycogen debranching enzyme cDNA is segmented into functional domains, with only the critical debranching catalytic domain being retained and packaged in the AAV vector. This segmentation allows the essential therapeutic function to be separated from non-essential sequences, enabling delivery within vector size constraints while maintaining therapeutic efficacy.
2Ease of operation
If standard AAV vectors are used for gene delivery, then delivery capability is achieved, but immune response is triggered
Solution Approach 1:
The patent modifies the nucleic acid sequence parameters by implementing codon optimization and CpG depletion. Codon optimization changes the codon usage to match host cell preferences for enhanced expression, while CpG depletion removes immunostimulatory CpG motifs from the sequence. These parameter changes maintain the delivery capability of AAV vectors while reducing the triggering of immune responses.
3Reliability
If full-length glycogen debranching enzyme is expressed, then complete enzymatic function is achieved, but vector packaging capacity is exceeded
Solution Approach 1:
The patent extracts the essential debranching catalytic domain from the full-length glycogen debranching enzyme gene, creating a truncated version that contains only the minimum necessary sequences for enzymatic function. This extracted functional core requires significantly fewer nucleotides while maintaining the ability to degrade limit dextrin and improve glycogen metabolism, thereby fitting within AAV packaging capacity.
Data Source
AI summary
Adult form glycogen storage disease type III (GSD III) is an orphan neuromuscular disorder caused by a deficiency of glycogen debranching enzyme. Long-term complications include progressive liver fibrosis, hepatic failure, and end-stage liver cirrhosis, and progressive muscle myopathy. Presently, there are no clinically approved therapies or cures for GSD III. Disclosed herein are compositions for and methods of treating and/or preventing GSD III disease progression.