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

HORIZON: A Phase II, Open-label, Outcomes-assessor Masked, Multicentre, Randomised, Controlled Study to Evaluate the Safety and Efficacy of Two Doses of GT005 Administered as a Single Subretinal Injection in Subjects With Geographic Atrophy Secondary to Dry Age-related Macular Degeneration

The purpose of this clinical study was to evaluate the safety and efficacy of two doses of GT005 administered as a single subretinal injection in subjects with geographic atrophy secondary to age-related macular degeneration (AMD).

This was a Phase II, open-label, outcomes-assessor masked, multicenter, randomized, controlled study designed to evaluate the safety and efficacy of two doses of GT005 administered as a single-time subretinal injection in subjects with Geographic atrophy (GA) secondary to Age-related macular degeneration (AMD).

Approximately 250 subjects, across Stage 1 and Stage 2, were planned to be randomized to one of two doses of GT005 or the untreated control group.

Subjects entered the study had genotyping and serum Complement factor I (CFI) levels assessed either through participation in a previous Gyroscope sponsored study, or a Sponsor-approved laboratory during the HORIZON screening period. If both eyes are eligible; the eye with the worse visual acuity will be selected as the study eye. If subjects failed to meet the eligibility criteria for this study, they were classified as screen failures and could be considered for entry into another Novartis/Gyroscope sponsored study.

After providing the informed consent, subjects underwent ophthalmic and clinical assessments to determined eligibility for inclusion in the study.

Upon confirmation of eligibility, subjects were randomized to one of two dose groups (medium dose [5E10 vg] or high dose [2E11 vg]). Within each dose group, subjects were allocated to GT005, or untreated control based on a 2:1 ratio. The overall study population (N=approximately 250) aimed to include approximately 60% of subjects with foveal GA and 40% of subjects with non-foveal GA (extrafoveal lesions). The study eye was identified for all subjects.

Enrolment for HORIZON were composed of two stages. Stage 1 enrolled subjects with foveal or non-foveal GA until 180 subjects were randomized. Stage 2 enrolled subjects with nonfoveal GA. Subjects with a CFI rare variant associated with normal or low serum CFI were also allowed to be enrolled in Stage 2, irrespective of GA foveal involvement.

Subjects were stratified by GA lesion size on Fundus autofluorescence (FAF) (≤10 mm2 or >10 mm2) and AMD genotype subgroup. Randomization of study eyes in the GA lesion size upper stratum of >10 mm2 to 17.5 mm2 was capped at 20% of total subjects randomized in Stage 1 and Stage 2, respectively. In Stage 2, once enrolment capping at 20% based on upper GA lesion size was reached, eyes that fulfilled the cap criteria were no longer eligible, unless the subject had a CFI rare variant genotype (minor allele frequency ≤1%) previously associated with normal or low serum CFI or had an unreported CFI rare variant genotype (Group 1 and 5). A permuted-block method was used to obtain an approximately 2:1 ratio between GT005 and the untreated control groups for each dose group within each stratum.

Following randomization, the Investigator was informed of the subject's allocated treatment (GT005 or the untreated control group) and the study eye selected. To minimize bias during imaging grading, all imaging endpoint assessments and grading were performed at a Central reading centre (CRC). All imaging efficacy assessments were performed in a masked fashion. The Sponsor, subjects, investigators, and study personnel performing clinical assessments remained masked to the dose received for those allocated to GT005.

For each subject, the study comprised of a screening period lasting up to 8 weeks (or up to 12 weeks if agreed by the Sponsor Medical Monitor) followed by a 96-week study period. All subjects were assessed for the occurrence of AEs at each visit and underwent functional assessments, retinal imaging, and biological sampling as per the schedule of assessments.

This study was conducted in compliance with Independent ethics committees (IECs) / Institutional review boards (IRBs), informed consent regulations, the Declaration of Helsinki, International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Good Clinical Practice (GCP) Guidelines, and the Food and Drug Administration (FDA), 21 Code of Federal Regulations (CFR) Part 11, Electronic Records, Electronic Signatures, and FDA, Guidance for Industry: Computerised Systems Used in Clinical Trials.

On 24-Aug-2023, the decision was taken to terminate the study and the GT005 program. The decision was aligned with the recommendation of an independent Data monitoring committee (DMC), which concluded that futility criteria had been met for the HORIZON study (GT005-03) and the overall benefit-risk ratio did not support continuation of the current development program as planned. All GT005- treated subjects, who were willing to be transferred into the long-term safety follow-up study were enrolled in the ORACLE (CPPY988A12203B) study.

Inclusion Criteria:

1. Able and willing to give written informed consent
2. Age ≥55 years
3. 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)
4. GA lesion(s) within an acceptable size on FAF, in the study eye
5. The GA lesion in the study eye must reside completely within the FAF image
6. Up to 25% of the enrolled study population are permitted to have CNV in the fellow eye
7. Have a BCVA of ≥24 letters (6/95 or 20/320 Snellen acuity equivalent), using ETDRS charts, in the study eye
8. 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
9. Able to attend all study visits and complete the study procedures
10. 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

Exclusion Criteria:

1. 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
2. Have a history, or evidence, of CNV in the study eye
3. Presence of moderate/severe or worse non-proliferative, diabetic retinopathy in the study eye
4. Have history of vitrectomy, sub-macular surgery, or macular photocoagulation in the study eye
5. History of intraocular surgery in the study eye within 12 weeks prior to Visit 1
6. Have clinically significant cataract that may require surgery during the study period in the study eye
7. 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
8. Axial myopia of greater than -8 diopters in the study eye
9. 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
10. Have received a gene or cell therapy at any time.
11. Have a contraindication to the protocol specified corticosteroid regimen
12. Are unwilling to use two forms of contraception (one of which being a barrier method) for 90 days post-dosing, if relevant
13. 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
14. 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