Safety study in cynomolgus monkeys after subretinal injection of rAAV.hPDE6A

Abstract

Purpose : A GLP conform toxicological study was performed in non-human primates (NHP) including subretinal injection of rAAV.hPDE6A in order to explore safety issues in preparation of a phase I/II clinical gene therapy trial.

Methods : Twenty-two purpose-bread NHPs (Macaca fascicularis) were allocated to either control (n=3 per sex) receiving vehicle only, low dose (1x10¹¹ vector genomes (vg)) or high dose (1x10¹² vg) groups (n=4 per sex). All relevant GLP-compliant safety parameters were obtained during the pre-dose phase, and at 4 and 12 weeks after dosing. Assessments included clinical observations, body weights, clinical pathology, electrocardiography (ECG), slit lamp examination as well as biodistribution in lacrimal and nasal fluid, blood, urine and tissues.

Results : No adverse or test item-related findings were noted on body weights, ECG, blood pressure, clinical pathology, urinalysis, or immunoglobulin evaluation. Test item-related microscopic findings were detected in the treated eye by histopathology. On an individual basis, three of eight high dose animals showed significant inflammatory findings that were considered adverse. These were characterized by slight focal mononuclear cell infiltration of the choroid associated with focal retinal atrophy, minimal multifocal mononuclear cell infiltration of the choroid as well as minimal multifocal retinal perivascular mononuclear cell infiltration, associated with focal retinal atrophy, and minimal multifocal mononuclear cell infiltration of the choroid, associated with retinal pigment epithelium and photoreceptor losses, and minimal focal retinal perivascular mononuclear cell infiltration.

Conclusions : Single subretinal administration of rAAV.hPDE6A was well tolerated at the dose of 1x10E11 vg. The higher dose of 1x10E12 vg was associated with ocular inflammatory changes, mainly focal and of low severity, that were considered adverse based on their potential impact on vision. There were no test item-related changes outside of the treated eye. The NOAEL (no-adverse-effect-level) for ocular toxicity is considered to be 1 x 10E11 vg in 0.15 ml. The NOAEL for systemic toxicity is above 1 x 10E12 vg in 0.15 ml. In terms of biodistribution, highest quantities of rAAV.hPDE6A DNA were detected in lymph nodes, spleen, optic nerve, and optic chiasm. The test item was shed via tear fluid, urine, and nasal mucus.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.