83. Relationship Between Immune Responses and Ocular Inflammation: What Is Learnt from Intravitreal Injection of rAAV2-2-ND4 (GS010) in Non-Human Primates and Leber Hereditary Optic Neuropathy (LHON) Patients
Authors: Céline Bouquet, Anne Galy, Serge Fitoussi, Sandrine Meunier, Roxane Noel, Scott Uretsky, Catherine Vignal, José A. sahel, Jean-Philippe Combal, Nitza Thomasson
Journal: Molecular Therapy (2016)

GenSight Biologics develops a rAAV2/2-ND4 vector (GS010) administered via intravitreal route (IVI) against vision loss in LHON patients bearing ND4 mutation. Gene therapy Adeno Associated Viral vectors are known to trigger host immune response which may interfere with safety and efficacy. Therefore, relationship between anti-AAV2 antibody systemic levels and eye inflammatory reactions following GS010 administration in non-human primates and LHON patients has been investigated. 36 non-human primates (NHP) and 15 LHON-ND4 patients (Phase I/IIa; ClinicalTrials. gov NCT02064569) underwent IVI of GS010 with two (4.3E10; 3.1E11 vg/eye) and four dose levels (9E9; 3E10; 9E10; 1.8E11 vg/eye) 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 and sera collected for neutralizing antibodies (Nabs) analysis (using a seroneutralization luciferase cell-based assay). 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 NAbs using the same method principle than for NHP. At baseline, NAbs were undetectable in 55% of NHPs and ranged between 1:5 and 1:400 titers for 45% of them. All animals showed titer increase up to 1:12800 starting week 2 post-injection. Between 2 and 6 months titers remained stable. Ocular inflammation (corneal punctuate focal opacity, vitreal haze, and superficial retinal mononuclear infiltration in histopathology) was observed in up to 80% of NHPs without deleterious effects on retinas. Preliminary Phase I/IIa data showed that, at baseline, 7 out of the 15 patients had undetectable serum NAb levels and 2 patients had titers above 1:1000. Prior treatment, none of the 8 tested patients had NAbs in aqueous humor, even the one showing a titer >2000 in serum. 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. This humoral response increase was not correlated to the dose level. At week 8, NAb titers remained above 1:1000 titer for 6 out of 15 patients; then titers tended to decrease progressively overtime. 13 out of 15 patients experienced mild to moderate ocular inflammation (anterior chamber inflammation and/or vitritis), responsive to standard medication, without apparent correlation with the humoral serum response. In conclusion, a humoral serum response against AAV2 was observed from 2 weeks post-injection of GS010 in both NHP and LHON patients. Ocular inflammation was reported, but currently no consistent correlation with anti-AAV2 antibody levels (at baseline or at the time-points when inflammation was recorded) were noted. Additional follow-up of humoral and cellular immunogenicity in upcoming nonclinical study and Phase III trials will help to confirm these observations and delineate the potential predictable impact for contralateral eye injection.