Abstract 16908: CTX310: An Investigational in vivo CRISPR-Based Therapy Efficiently and Durably Reduces ANGPTL3 Protein and Triglyceride Levels in Non-Human Primates After a Single Dose

Abstract

Background: Angiopoietin-like 3 (ANGPTL3) is a key regulator of lipid metabolism. In humans, naturally occurring loss-of-function variants in ANGPTL3 are associated with reduced levels of serum lipids and reduced risk of atherosclerotic cardiovascular disease. CTX310™ is an investigational in vivo CRISPR/Cas9 gene editing therapy designed to knock out hepatic expression of ANGPTL3. CTX310 consists of Cas9 mRNA and guide RNA (gRNA) targeting ANGPTL3 encapsulated into lipid nanoparticles (LNPs). Here we assessed the efficacy, safety, and durability of CTX310 in primary human cells, mice, and non-human primates (NHPs). Methods: CTX310 was evaluated in vitro in primary human hepatocytes (PHHs), in vivo in wildtype C57BL/6J and LDLR-/- mice using a mouse surrogate gRNA, and in vivo in NHPs where the human target sequence is conserved. For the NHP studies, cynomolgus monkeys were infused with a single dose of CTX310 at doses ranging from 0.5 to 3.0 mg/kg to evaluate efficacy (N=32) and durability (N=8). Results: In PHHs, >90% on-target editing was achieved with CTX310, leading to a >90% reduction in ANGPTL3 production. Comprehensive genomic assessment indicated no sign of unintended genomic changes introduced by CTX310. In wildtype mice administered LNPs containing a mouse surrogate gRNA along with the same Cas9 mRNA and lipid components as CTX310, ~50% liver editing yielded a >95% reduction in plasma ANGPTL3 protein and ~40% reduction in triglyceride levels, sustained up to nine months post-dosing. Similar levels of editing and efficacy were observed in LDLR-/- mice, suggesting an LDLR-independent uptake mechanism.In NHPs, dose-dependent editing of ANGPTL3 in the liver of up to 71% was observed, resulting in reduced levels of plasma ANGPTL3 protein (up to 86%) and triglycerides (up to 64%). Reductions in ANGPTL3 protein and triglycerides were durable past 32 weeks. As is commonly observed with LNP delivery, transient elevation of liver enzymes was observed and resolved within 14 days without intervention. Conclusion: CTX310 was well-tolerated in NHPs and led to significant and durable reductions in circulating ANGPTL3 and triglycerides. This data suggests that CTX310 could be used to treat dyslipidemias in humans.