Intravitreal injection of rAAV2/2–ND4 (GS010): immune responses and ocular inflammation in non-human primates and patients with Leber Hereditary Optic Neuropathy (LHON)

Abstract

Purpose : AAV viral vectors are known to trigger host immune response which may affect safety and efficacy of gene therapies. Intravitreal injection (IVI) of GS010, a rAAV2/2-ND4 vector, is developed for treatment of vision loss in LHON-ND4 patients. We thus investigated the relationship between anti-AAV2 antibody levels and local inflammatory reactions after GS010 administration.

Methods : Non-human primates (NHP; n=3M+3F per group) and LHON-ND4 patients (Phase I/IIa; injection in the worst seeing-eye) underwent IVI of GS010 with two (4.3^E11; 3.1^E11 vg/eye) and four dose levels (9^E9; 3^E10; 9^E10; 1.8^E11 vg/eye; n=3 per dose + 3 at the recommended 9^E10 dose) respectively. Ocular examinations were performed up to 6 months post-injection in NHP and up to 48 weeks in patients. NHP eye histopathology was performed. Serum was collected from all patients and aqueous humor samples prior to injection in the last 8 patients, for quantification of anti-AAV2 IgG by ELISA and neutralizing antibodies (NAbs) by luciferase assay on HEK 293 cells.

Results : At baseline, 55% of NHPs had undetectable NAb titers and 45% had titers of 1:5–1:400. All animals showed titer increase up to 1:12800 starting week 2 post-injection. Between 2 and 6 months titers remained stable. Ocular inflammation was observed in up to 80% of NHPs, but without deleterious effects on retinas.
Preliminary Phase I/IIa data showed that 7 out of the 15 patients had undetectable NAb levels at baseline. Two weeks after injection, IgG titers increased up to 19 times their baseline level in 7 patients and NAbs up to 39 times in 10 patients. No obvious correlation with the dose level was observed. Eleven of 15 patients experienced ocular inflammation without apparent correlation with the humoral serum response. Antibody titers and NAbs in aqueous humor at baseline are still under evaluation.

Conclusions : A humoral serum response against AAV2 was induced from 2 weeks post-IVI of GS010 in both NHP and humans. Ocular inflammations were also observed, but currently no consistent correlation with antibody levels are noted. Additional follow-up of humoral and cellular immunogenicity in upcoming nonclinical study and Phase III trials will help to confirm these observations and the potential predictable impact for contralateral eye injection.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.