Metagenomi Announced The Presentation Of Three Abstracts At The American Society Of Gene & Cell Therapy Annual Meeting

• Potential best-in-class extrahepatic in vivo gene editing with all-in-one delivery to the central nervous system (CNS) is a critical milestone for the treatment of neurological disorders.
• Advancements demonstrate the ability to specifically integrate correct copies of complete genes, potentially enabling treatment of any disease caused by a loss-of-function mutation.

Key highlights from the company's three poster presentations at ASGCT are below.

A Compact and Potent Type II CRISPR System for CNS Gene Knockdown via AAV Delivery

• MG21-1 is a novel, compact type II nuclease comprising 1,098 amino acids that, when delivered with its guide RNA in a single adeno-associated virus (AAV), achieved strong protein knockdown in the CNS.
• In vivo, localized injection of AAV9 packaged with MG21-1 in the mouse motor cortex produced up to 69% target protein reduction.
• Systemic delivery with a blood-brain barrier-crossing capsid resulted in 82% protein knockdown in the brain and 71% in the brainstem.
• These results demonstrate the potential of a small CRISPR nuclease to efficiently knock-down targets in the CNS using a single AAV injected locally or systemically.

In Vivo Genome Editing with an Ultra-Compact Type V Nuclease for All-In-One AAV Delivery 

• MG119-28 is an ultra-compact engineered type V nuclease consisting of 488 amino acids and capable of efficient genome editing across multiple cultured cell tissues when delivered using a single AAV vector.
• In vitro, this nuclease restored dystrophin protein levels by over 50% in Duchenne muscular dystrophy (DMD) model myocytes and achieved complete gene disruption at a therapeutically relevant target locus in K562 human cells.
• In vivo, AAV9-mediated delivery to the mouse CNS via stereotactic injection resulted in up to 52% editing efficiency in olfactory bulb nuclei and produced 64% knockdown of the target protein in the motor cortex.
• These results highlight the potential of this ultra-compact nuclease to deliver AAV-based therapeutic genome editing beyond the liver, with implications for treating neuromuscular and neurodegenerative disorders.

Site-Specific Integration of Therapeutic Transgenes with a Type V-K CAST System Engineered for Efficient and Targeted Human Genome Editing 

• The data demonstrate that CRISPR-associated transposases (CAST) protein engineering and delivery optimization enables efficient integration of diverse cargo designs across different cell types and target loci, including with therapeutically relevant delivery approaches that are required for in vivo editing.
• Through structure and AI-guided protein design, integration efficiency of a compact type V-K CAST system derived from uncultivated microbes was improved by >50x compared with the natural system.
• Functional activity translated to primary mammalian cells, a key step in development for human therapeutic applications.
• These results suggest that type V-K CAST are promising systems for site-specific programmable integration of gene-sized donors for therapeutic and biotechnological development.