Silica Nanocapsule-Mediated Nonviral Delivery of CRISPR Base Editor mRNA and Allele Specific sgRNA for Gene Correction in Leber Congenital Amaurosis

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PROJECT SUMMARY/ABSTRACT - LEAD TRAILBLAZER PROJECT 1 Leber Congenital Amaurosis (LCA) is a rare but severe form of pediatric blindness. One subtype, LCA16, is caused by several single-point mutations in the KCNJ13 gene, which encodes the inwardly-rectifying potassium channel Kir7.1 in the retina. There is no FDA-approved treatment for ultra-rare conditions such as LCA16. The objective of Lead Project 1 is to develop a new LCA16 gene therapy utilizing a CRISPR base editor (BE) delivered to the retinal pigment epithelium (RPE) via a nonviral silica nanocapsule (SNC). The SNCs possess many desirable properties, including high delivery efficiency, versatile surface chemistry for ligand conjugation, small particle sizes, good biocompatibility, and scalable production. In preliminary studies, we show that the SNC can transiently deliver a wide range of biologics, including a BE to RPE cells in mice and LCA16 patient-derived induced pluripotent stem cell (iPSC)-RPE. Within five years, we seek to optimize and validate a lead candidate, SNC-101, progress to scaled-up and CGMP production of the product to enable non-human primate (NHP) studies and file an Investigational New Drug (IND) application to the FDA for base editing therapy of LCA16. In Aim 1, we will generate a preclinical validation package with a lead SNC formulation for W53* KCNJ13 correction. We will first optimize the amount of ATRA targeting ligand (RPE cell-specific) and the modified KCNJ13 sgRNA in vitro via the Human Cell Assays Core and in vivo in a W53* LCA16 mouse model. We will then develop a scale-up production process for the optimized SNC (i.e., SNC101) for preclinical studies. We plan to complete one INTERACT meeting at the end of this aim. In Aim 2, we will determine the gene correction efficiency, dosing, and toxicity in mouse models and NHPs. We will comprehensively evaluate the immune, structural, and functional consequences of subretinal delivery of SNC-101 through our W53* LCA16 mouse model. Using our Large Animal Core, we will also perform dose-escalation safety studies in NHPs. Alongside the species comparison, the study will ascertain storage stability, dosing, and toxicity profiles in detail, an important milestone to support an IND with the FDA. In Aim 3, we will conduct IND enabling studies of SNC-101 for W53* KCNJ13 correction. A pre-IND meeting package will be submitted to FDA CBER with the help of our Regulatory Core. Waisman Biomanufacturing will develop a full-scale engineering run to be used in GLP toxicology study in rats and NHPs. Concurrent with the toxicology study, one entire CGMP batch will be manufactured. We will submit an IND application to the FDA in the final year. To date, no nonviral genome editing therapeutic has reached an IND in the eye. Success here with SNC-101 would pave the way for this new therapeutic modality. Finally, the knowledge gained along this development path will accelerate the translation of other nonviral genome editing leads, including SNC-201 and TAGE-101, in the Follower Projects of the CRISPR Vision Program.