Intellia Therapeutics, Inc. has presented preclinical data demonstrating in vivo gene editing using lipid nanoparticles (LNPs) to deliver CRISPR/Cas9. These data were presented at the 2016 meeting on Genome Engineering: The CRISPR/Cas Revolution, in Cold Spring Harbor, New York.
In several in vitro and in vivo preclinical studies, the data demonstrated:
• Editing efficiency in mouse liver of up to approximately 60 percent at the transthyretin (TTR) target site after a single intravenous administration, consistently across different lobes. This resulted in an associated decrease in serum TTR protein levels of up to approximately 80 percent;
• Dose-dependent editing by LNP delivery;
• Undetectable Cas9 mRNA and guide RNA (gRNA) in the liver at 72 hours post administration;
• Repair patterns in mouse liver cells in vivo being best predicted by primary mouse liver cells in vitro.
“Intellia has shown robust data that demonstrates the clinical potential of the LNP delivery of CRISPR components. With a single administration, we show significant editing at the target gene and a related decrease in target protein in serum,” said David Morrissey, Ph.D., Chief Technology Officer, Intellia Therapeutics. “These early data also show that LNP delivery can lead to rapid clearance of the Cas9 and guide components from the liver, an important consideration for future clinical studies. Intellia continues to make further advances, and we would expect greater editing efficiency with continued optimization.”
The preclinical editing studies were designed to explore the use of lipid nanoparticles for delivery of CRISPR/Cas9 components to the liver in mice and to mediate editing of target DNA within hepatocytes. In general, for the LNPs in the studies, Cas9 mRNA was co-formulated with chemically synthesized gRNAs targeting the mouse TTR gene, and administered via one or two intravenous tail vein injections. Additional studies were performed to evaluate the impact on editing of variables including guide format, dosing regimen and dose escalation.