Large Animal Core

PROJECT SUMMARY/ABSTRACT – LARGE ANIMAL CORE To achieve the aims of the CRISPR Vision Program, it will be critically important to determine acceptable dosage and toxicity levels (if any) of therapeutic candidates using nonhuman primates (NHPs). The NHP eye has much greater similarity to the human eye than that of any other species commonly used for research and drug testing. For example, the NHP is the only non-human mammal that has a macula. In humans, the macula is susceptible to a number of pathological conditions such as age-related macular degeneration and is often the part of the human retina most adversely affected by drug toxicity. Hence, evaluating the effects of test articles containing genome editors on the NHP eye, and the macula in particular, will be highly informative for safety assessments by the FDA. The Large Animal Core will provide the surgical and in vivo testing expertise to determine the suitability and practicality of the proposed subretinal dosing route in NHPs. The Large Animal Core will also monitor the NHPs during and after test article dosing for signs of both local (i.e., proximal to the subretinal bleb) and distal retinal and general ocular toxicity. The animals will be monitored for behavior and other indications of systemic toxicity, as well. The Core will be administered under the following three Tasks to support all of the CRISPR Vision Projects. In Task 1, the Large Animal Core will administer the test article subretinally in a surgically sterile manner using a trans-vitreous approach, small-gauge pars plana vitrectomy equipment, and automated subretinal injector. In Task 2, the Large Animal Core will perform in vivo toxicity evaluations. The animals will be monitored both functionally and morphologically for in vivo signs of ocular toxicity following subretinal dosing. Photopic and scotopic full-field electroretinography (ERG) testing will determine the health of the entire retina. Photopic multifocal ERG will be used to assess possible localized retinal injury, either from the subretinal injection procedure itself or localized toxicity of the test article. Morphological determinations will include ocular examinations, color fundus photographs, fluorescein angiography and spectral domain optical coherence tomography. In Task 3, the Large Animal Core will perform necropsy and eye retrieval for purposes of determining drug distribution and histopathological signs of drug toxicity. The expertise and centralization of these studies in the Large Animal Core will ensure efficient, standardized assessment of lead therapeutic products nominated by all three CRISPR Vision Program Projects, with near real-time data return to inform Project evolution. The extensive history of the Core Lead, Dr. Nork, with developing methods for subretinal injection and ocular evaluations will provide nimble protocol innovation if required over the span of the partner Projects.