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Ryan F. Boyd, Joshua T. Bartoe, Thomas S Vihtelic, Sanford L Boye, Shannon Elizabeth Boye; Subfoveal Injections in Non-Human Primates: Safety and Efficacy Following Administration of a Photoreceptor-Targeted AAV5. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5662.
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© ARVO (1962-2015); The Authors (2016-present)
Subfoveal delivery of AAV has become standard of care in some gene therapy clinical trials, with vitrectomy performed prior to vector injection. We proposed that subfoveal injections could be successfully performed in primates with maintenance of an intact vitreous humor.
Four cynomolgus macaques were injected bilaterally with AAV5 containing the hGRK1 promoter driving GFP at a concentration of 1e12 vg/ml. A three-step injection was utilized, with a small volume of fluid used to induce foveal detachment, followed by aqueous paracentesis, then vector solution injection to expand the subretinal bleb. In two animals, vehicle was used to induce foveal detachment, then 100µL of AAV5 for bleb enlargement (Group 1). In the other two animals, a total of 100µL AAV5 was used for both steps (Group 2). Serum neutralizing antibodies (Nab) were analyzed pretest and at study termination 6 weeks post-injection. Ophthalmic examinations, optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy (cSLO) were performed at regular intervals.
Subfoveal delivery of AAV5 was accomplished in all 8 eyes. One Group 2 eye only received 50µL AAV5 after development of apparent retinal tension during injection. One Group 1 eye developed a macular hole after an air bubble was inadvertently introduced during bleb enlargement. The macular hole showed resolution on OCT after 1 week, but a subfoveal detachment persisted through study termination. Remaining eyes had resolution of detachment at 1 week, and return of the ellipsoid zone and foveal bulge in 5/7 eyes by study termination. cSLO revealed faint GFP fluorescence at 1 week, becoming progressively stronger through 6 weeks. Mild uveitis was evident in the animal with a macular hole at 1 week post-injection, but resolved by week 2 with anti-inflammatory treatment. Both Group 2 animals developed minimal intermediate uveitis in both eyes from weeks 1 through 6. NAb titers were negative in all animals pretest. One Group 2 animal developed a strong anti-AAV5 response at 6 weeks, while responses in all other animals were modest.
This three-step subfoveal injection without vitrectomy is effective for delivery of AAV in normal macaques. Use of vehicle instead of AAV vector solution to create the initial foveal detachment may decrease subsequent vitreal inflammation, and may have an impact on NAb formation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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