Foveal detachment in patients undergoing gene therapy for Stargardt disease (STGD1, MIM #248200)

Abstract

Purpose: To present the clinical findings and early outcomes of two trial participants with Stargardt Disease who experienced foveal detachment following subretinal injections of StarGen^TM.

Methods: The StarGen^TM study (NCT01736592) is a Phase I/IIa, open-label, gene therapy, dose escalation, safety study of subretinally injected lentiviral vector, administered to patients with Stargardt Disease. The surgical protocol calls for a retinotomy to be performed temporal to the optic nerve outside of the superior vessel arcade. In two patients the subretinal bleb extended into the macula and detached the fovea. As per trial protocol, these participants were evaluated at baseline, postop Day 1, and postop Weeks 1, 2, 4, 12, 24, 36 and 48. Functional visual evaluations included Best-Corrected Visual Acuity in ETDRS letter score, kinetic visual field (VF), and hill of vision calculated from static visual fields. The ocular and retinal structural changes were assessed by slit lamp examination, fundoscopy, spectral domain optical coherence tomography (SD-OCT), and fundus autofluorescence (FAF).

Results: Best-Corrected Visual Acuity in ETDRS letter score and VF values declined immediately following the injection, but returned to the baseline values by Week 12 and remained unchanged by Week 48. No new scotomas were observed. The subretinal fluid resolved and the macula was re-attached by Week 1-2 after the injection. There were no retinal pigment epithelium or retinal changes in the macula. FAF showed an area of hypofluorescence developing at the site of the retinotomy.

Conclusions: This experience provides important information regarding the safety of placing a bleb underneath the fovea in patients with Stargardt disease. There was no evidence of direct retinal toxicity or ocular inflammatory response in these two patients with extension of the subretinal injections of the lentiviral vector.