Treatment response to avacincaptad pegol by baseline patient characteristics: A prespecified subgroup analysis of the phase 3 GATHER2 study

Abstract

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 baseline patient and imaging 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 for the study. Patients received 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 baseline patient and lesion 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 2 mg (n=225) or sham (n=222). The primary objective was met at 12 months. Treatment with ACP 2 mg 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) versus sham. In the prespecified subgroup analysis, the mean rate of GA growth (slope) was consistently lower in the ACP 2 mg group compared to the sham group. The treatment differences in subgroups ranged from 0.031 mm to 0.085 mm (Figure 1).

Conclusions : In this prespecified subgroup analysis of GATHER2, treatment effect on GA lesion growth rate over 12 months was consistently noted for ACP 2 mg versus sham in all analyzed baseline characteristic subgroups.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1: Prespecified subgroup analysis of GATHER2 shows treatment effect of ACP in all prespecified subgroups