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Treatment response to avacincaptad pegol by patient baseline characteristics: A prespecified subgroup analysis of the phase 3 GATHER2 study
Michael S Ip, MD1; Peter K Kaiser, MD2; David R Lally, MD3; Glenn J Jaffe, MD4; Arshad M Khanani, MD, MA5; Charles C Wykoff, MD, PhD6; Jeffrey S Heier, MD7; Justin Tang, PhD8; Liansheng Zhu, PhD8; Julie Clark, MD8
1. Doheny Eye Institute, UCLA Stein Eye Institute, Arcadia, CA, USA
2. Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
3. New England Retina Consultants, Springfield, MA, USA
4. Department of Ophthalmology, Duke University, Durham, NC, USA
5. Sierra Eye Associates, Reno, NV, USA; University of Nevada, Reno School of Medicine, Reno, NV, USA
6. Retina Consultants of Texas; Retina Consultants of America; Blanton Eye Institute, Houston Methodist Hospital, Houston, TX, USA
7. Ophthalmic Consultants of Boston, Boston, MA, USA
8. Iveric Bio, Cranbury, NJ, USA.
Purpose: Treatment of geographic atrophy (GA) with avacincaptad pegol (ACP), an inhibitor of complement C5, has been investigated in two pivotal phase 3 studies. The aim of this prespecified subgroup analysis of the GATHER2 study was to explore consistency of treatment response to ACP 2 mg based on patient and imaging baseline characteristics over 12 months in patients with GA.
Methods: GATHER2 was a randomized, double-masked, sham-controlled, phase 3 study that evaluated the safety and efficacy of ACP 2 mg compared to sham in eyes with GA. Eyes with GA lesions that were non-center point involving and in part within 1500 µm from the foveal center in the study eye were eligible to participate. Patients were randomized 1:1 to receive monthly intravitreal injections of ACP 2 mg or sham for 12 months. The primary analysis was defined as the mean rate of growth (slope) based on GA area measured by fundus autofluorescence (FAF) at baseline, Month 6, and Month 12 (square root transformation). A prespecified subgroup analysis was performed on patient and lesion baseline characteristics (eg, disc area, best corrected visual acuity, FAF pattern, age, sex) to explore consistency of treatment response over 12 months.
Results: A total of 447 eyes of 447 patients were randomized and treated with ACP (n=225) or sham (n=222). The primary objective was met at 12 months. Treatment with ACP resulted in a statistically significant reduction of 0.056 mm (p=0.0064; 95% CI: 0.016, 0.096 mm) in mean rate of GA growth (slope) vs sham. In the prespecified subgroup analysis, mean rate of GA growth (slope) was consistently lower in the ACP group than in the sham group. The treatment differences in subgroups ranged from 0.031-0.085 mm using square root transformed data and 0.114-0.441 mm2 using observed data (Figure).
Conclusion: In this prespecified subgroup analysis of GATHER2, treatment effect on GA lesion growth rate over 12 months was consistently noted for ACP 2 mg vs sham in all analyzed baseline characteristic subgroups.