HORIZON: A Phase II Study to Evaluate the Safety and Efficacy of Two Doses of GT005

Prior treatment

• History of intraocular surgery in the study eye within 12 weeks prior to Visit 1
• Have clinically significant cataract that may require surgery during the study period in the study eye
• Have received any investigational product for the treatment of GA within the past 6 months or 5 half-lives (whichever is longer), other than nutritional supplements such as the age-related eye disease study (AREDS) formula
• Have received a gene or cell therapy at any time.
• Have a contraindication to the protocol specified corticosteroid regimen

Other illness

• a. In Stage 1: Carriers of excluded genetic variants; b. In Stage 2: Subjects are excluded if they have a clinical diagnosis of Stargardt Disease or other retinal dystrophies
• Have history of vitrectomy, sub-macular surgery, or macular photocoagulation in the study eye
• Presence of moderate to severe glaucomatous optic neuropathy, uncontrolled intraocular pressure (IOP), despite use of two or more topical agents; or a history of glaucoma-filtering or valve surgery
• Active malignancy within the past 12 months, except for appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, or prostate cancer with a stable prostate-specific antigen (PSA) ≥ 12 months
• Have any other significant ocular or non-ocular medical or psychiatric condition which, in the opinion of the Investigator, may either put the subject at risk or may influence the results of the study

Other

• Have a history, or evidence, of CNV in the study eye
• Presence of moderate/severe or worse non-proliferative, diabetic retinopathy in the study eye
• Axial myopia of greater than -8 diopters in the study eye
• Are unwilling to use two forms of contraception (one of which being a barrier method) for 90 days post-dosing, if relevant

• Able and willing to give written informed consent
• Age ≥55 years
• a. In Stage 1: Have a clinical diagnosis of GA secondary to AMD in the study eye, as determined by the Investigator, and a diagnosis of AMD in the contralateral eye; b. In Stage 2: Have a clinical diagnosis of GA secondary to AMD in the study eye, as determined by the Investigator, that is non-foveal, as determined by the central reading centre, or has a CFI rare variant genotype and meets inclusion criteria 3a, and a diagnosis of AMD in the contralateral eye (except if monocular)
• GA lesion(s) within an acceptable size on FAF, in the study eye
• The GA lesion in the study eye must reside completely within the FAF image
• Up to 25% of the enrolled study population are permitted to have CNV in the fellow eye
• Have a BCVA of ≥24 letters (6/95 or 20/320 Snellen acuity equivalent), using ETDRS charts, in the study eye
• a. In Stage 1: Meet one of the pre-specified AMD genetic subgroup criteria; b. In Stage 2: Genotyping is not required for study eligibility
• Able to attend all study visits and complete the study procedures
• Women of child-bearing potential must have a negative pregnancy test within 2 weeks prior to randomisation (not required for postmenopausal women) or provide documentation of being surgically sterilised