Microdystrophin AAV Constructs Under Viral Payload Limits

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Solution Overview

Problem

Existing adeno-associated virus (AAV) vectors face limitations in payload size, making it challenging to effectively deliver micro- or mini-dystrophins for treating dystrophinopathies like Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) while minimizing immune responses.

Innovation Solution

Development of recombinant AAV vectors encoding microdystrophin proteins, comprising specific dystrophin domains, optimized for expression in muscle and CNS cells, with reduced immunogenicity and improved cardioprotective functions, using muscle-specific and CNS-specific promoters, and incorporating introns like VH4 for enhanced expression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If full-length dystrophin gene is used for therapy, then therapeutic efficacy is improved, but vector payload capacity is exceeded

Engineering Contradiction:

Improvetherapeutic efficacyVSAvoidvector payload capacity

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The dystrophin gene is divided into multiple exons, and specific exons are selectively included or excluded to create mini-dystrophin variants that fit within AAV payload capacity while retaining essential functional domains for therapeutic efficacy

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Non-essential or redundant portions of the full-length dystrophin gene are extracted and removed, keeping only the critical functional domains required for muscle function and cardioprotection, thereby reducing gene size to fit viral vector constraints

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If larger gene constructs are delivered, then therapeutic function is improved, but immune response increases

Engineering Contradiction:

Improvetherapeutic functionVSAvoidimmune response

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Immunogenic sequences are identified and extracted from the dystrophin gene construct, removing portions that trigger strong immune responses while preserving the essential therapeutic functional domains

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The gene construct parameters are modified by adjusting exon composition and sequence composition to reduce immunogenicity while maintaining therapeutic function, creating optimized mini-dystrophin variants

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If mini-dystrophin is used to fit vector capacity, then vector payload capacity is satisfied, but therapeutic efficacy is reduced

Engineering Contradiction:

Improvevector payload capacityVSAvoidtherapeutic efficacy

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

Different regions of the dystrophin protein are selectively retained or removed based on their functional importance, preserving local domains critical for muscle function and cardioprotection while eliminating non-essential regions to reduce overall size

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250367328A1Methods of manufacturing microdystrophin gene therapy constructs

Publication Date: 2025.12.04 REGENXBIO INC

AI summary

Provided is an invention based, in part, on novel gene constructs that encode a microdystrophin protein for use in gene therapy. The microdystrophin gene constructs and expression cassettes were engineered for improved therapy with respect to efficacy, potency and safety to the subject when expressed by a viral vector in muscle cells and/or CNS cells.