Replication study of in vivo postnatal gene editing for metabolic liver disease in the nonhuman primate model

PROJECT SUMMARY / ABSTRACT This application is being submitted in response to the Notice of Special Interest (NOSI) identified as NOT-RM- 24-009. As part of our NIH Common Fund’s Somatic Cell Genome Editing Program-funded U19 cooperative agreement (U19NS132301), we are seeking to develop and perform IND-enabling studies with gene-editing therapies for phenylketonuria (PKU) and hereditary tyrosinemia type 1 (HT1), using lipid nanoparticles (LNPs) as the delivery method. However, there are currently no clinical-grade LNP formulations available for unrestricted use by academic investigators. To enable our therapies, we have developed our own LNP formulation comprising four lipid excipients, a messenger RNA (mRNA) encoding a gene-editing protein, and a guide RNA (gRNA). In a proof-of-concept preclinical study performed in our internal academic animal facility, we dosed each of four juvenile cynomolgus monkeys with a single dose of LNPs with an adenine base editor mRNA and a gRNA targeting the PCSK9 gene, a well-validated gene editing target. Three weeks following treatment, we observed 42-55% whole-liver editing of the PCSK9 gene with concomitant reduction of blood LDL cholesterol—editing levels compatible with treatment of PKU, HT1, and a variety of other diseases. The LNPs were well tolerated, with no perturbation of liver function tests (LFTs). We propose to undertake a replication study with our internally produced LNPs, administered to cynomolgus monkeys by an NIH-selected contract research organization (CRO), to confirm the robustness of our pilot observations on efficacy and safety. Validation of our LNP formulation will: (1) provide critical information for IND applications for PKU, HT1, and other diseases; (2) enable the production of clinical-grade gene-editing therapies for use in our investigator-initiated early-phase clinical trials; and (3) broadly enable academic investigators to pursue the development of LNP-based gene-editing therapies by making a non-commercial LNP option available to the scientific community.