Highlight
- Ellipsoid zone (EZ) integrity measured by spectral-domain optical coherence tomography (SD-OCT) is a critical biomarker of photoreceptor health in geographic atrophy (GA).
- Greater baseline EZ attenuation correlates with faster GA lesion growth, affirming EZ measures as predictors of AMD progression.
- Avacincaptad pegol (ACP), a complement C5 inhibitor, significantly slows both total and partial EZ degradation over 12 months compared to sham treatment.
- EZ integrity metrics can guide early therapeutic intervention strategies for patients at high risk of GA progression.
Study Background
Geographic atrophy (GA) represents an advanced, visually debilitating form of age-related macular degeneration (AMD), characterized by progressive loss of retinal pigment epithelium (RPE) and photoreceptor degeneration. Photoreceptor cell integrity directly correlates with preserved vision, making assessment of ellipsoid zone (EZ) continuity—a hyperreflective band in the outer retina detectable by spectral-domain optical coherence tomography (SD-OCT)—an important imaging biomarker. Recent advancements in complement pathway inhibition have positioned agents such as avacincaptad pegol (ACP) as promising therapies to slow GA progression. However, the impact of complement inhibition on EZ integrity, which reflects photoreceptor viability, has remained understudied. This post hoc analysis addresses the clinical importance of EZ integrity as a surrogate for photoreceptor health and evaluates the effect of ACP on EZ preservation in well-characterized clinical trial cohorts.
Study Design
This analysis pooled data from the phase 2/3 GATHER1 and phase 3 GATHER2 randomized clinical trials, comprising a total of 624 eyes (292 treated with ACP 2 mg, 332 sham control) from patients aged 50 years or older with non–center-involving GA. The study’s outcomes included assessment of EZ integrity measured by advanced multilayer segmentation on SD-OCT images, focusing on both total EZ attenuation (EZ to RPE thickness of 0 µm, indicating total loss) and partial EZ attenuation (EZ-RPE thickness ≤20 µm, indicating degradation). GA lesion growth was quantified using fundus autofluorescence imaging over a 12-month period. The primary aims were to (1) correlate baseline EZ integrity measures with natural history GA progression in sham-treated eyes and (2) determine the impact of avacincaptad pegol treatment on EZ attenuation progression compared to sham.
Key Findings
Baseline EZ attenuation demonstrated a strong association with GA progression in sham-treated patients. Eyes stratified into higher quartiles based on total or partial EZ attenuation exhibited significantly greater GA lesion growth and faster EZ deterioration. Specifically, eyes with more extensive baseline EZ loss showed accelerated photoreceptor degradation over 12 months, reinforcing EZ metrics as robust prognostic biomarkers.
Treatment with avacincaptad pegol yielded statistically significant reductions in EZ loss. The mean growth in total EZ attenuation was decreased by 19.5% (P=0.0009) relative to sham-treated eyes, implicating a meaningful protective effect on complete photoreceptor loss. Strikingly, partial EZ attenuation progression was reduced by 55.3% (P<0.0001), suggesting marked preservation of vulnerable photoreceptor zones that might otherwise deteriorate.
These effects were consistent across pooled trial data, emphasizing the reproducibility of ACP’s efficacy in preserving photoreceptor architecture. Given that EZ integrity is closely linked with visual function, these findings indicate that complement inhibition via ACP extends benefits beyond reduction of GA lesion area to include photoreceptor survival.
Expert Commentary
Preservation of the ellipsoid zone has long been recognized as a critical correlate of functional vision in AMD. This analysis robustly establishes EZ attenuation metrics as not merely imaging endpoints but as prognostic indicators for disease progression. It affirms that targeting the complement cascade—specifically the C5 component—with avacincaptad pegol confers a cytoprotective effect on photoreceptors, potentially translating to clinical vision benefits.
However, limitations include the post hoc nature of the analysis and aggregation of data from two separate trials, which may introduce heterogeneity. Longer-term data on functional outcomes and safety beyond 12 months are also needed. Additionally, while EZ measures provide intimate insights into photoreceptor status, integration with functional testing such as microperimetry or visual acuity measures would further validate clinical relevance.
Biologically, the complement cascade’s involvement in AMD pathogenesis is well established, with complement activation implicated in chronic inflammation and retinal cell death. By inhibiting C5, ACP presumably reduces downstream membrane attack complex formation and neuroinflammation, curbing photoreceptor destruction in GA.
Conclusion
This post hoc analysis from GATHER1 and GATHER2 trials highlights the crucial prognostic value of ellipsoid zone integrity in geographic atrophy progression. Avacincaptad pegol treatment demonstrably slows EZ degradation, potentially preserving photoreceptor function and delaying vision loss. EZ assessment via advanced SD-OCT imaging should be considered an integral biomarker for risk stratification and monitoring therapeutic response in AMD. These findings reinforce complement inhibition as a viable therapeutic avenue in GA and support early intervention in patients exhibiting EZ attenuation to optimize clinical outcomes.
Funding and Clinical Trials Registration
The original clinical trials were supported by the sponsor of the GATHER studies. Full details of trial registration can be found at clinicaltrials.gov under identifiers associated with GATHER1 and GATHER2.
References
1. Ehlers JP et al. Avacincaptad Pegol Slows Progressive Ellipsoid Zone Degradation/Loss in Eyes With Geographic Atrophy. Ophthalmology. 2026 Jun 30; PMID:42379522.
2. Jaffe GJ, et al. Complement 5 Inhibitor Avacincaptad Pegol for Geographic Atrophy Secondary to AMD: GATHER Phase 3 Trial Results. Ophthalmology. 2023.
3. Sadda SR, et al. The role of ellipsoid zone integrity in retinal degenerative diseases. Prog Retin Eye Res. 2021;
4. Holz FG, et al. Geographic Atrophy: Clinical Characteristics and Role of Imaging Biomarkers. Am J Ophthalmol. 2018.