Geographic Atrophy & Complement Inhibitors: Syfovre & Izervay Macular Therapies

The complement system is an ancient branch of innate immunity designed to destroy invading bacteria. In genetic variants of AMD (mutations in Complement Factor H, $CFH$), the body loses the ability to downregulate complement activation on its own retinal cells:

$$\text{C3 Cleavage } \longrightarrow \text{C3a} + \text{C3b} \longrightarrow \text{C5 Convertase} \longrightarrow \text{C5b-9} \text{ (Membrane Attack Complex)}$$

The terminal Membrane Attack Complex (MAC, C5b-9) punches microscopic pores directly into RPE cell membranes, causing osmotic lysis, cellular death, and expanding geographic atrophy lesions.

The newly approved therapeutics interrupt this destructive cascade at different enzymatic checkpoints:

• Pegcetacoplan (Syfovre, Apellis): A pegylated bicyclic peptide that binds and blocks both C3 and C3b, shutting down all three complement pathways (classical, lectin, and alternative). Clinical trials (OAKS and DERBY) demonstrated a 20% to 22% reduction in lesion growth rate over 24 months.
• Avacincaptad Pegol (Izervay, Iveric Bio/Astellas): A pegylated RNA aptamer that selectively binds Complement C5, preventing its cleavage into C5a and C5b. GATHER1 and GATHER2 trials showed a 14% to 18% slowdown in lesion expansion with a low rate of secondary wet AMD conversion.

On blue-light Fundus Autofluorescence (FAF) imaging, geographic atrophy displays a distinctive signature:

1. Central Hypoautofluorescence (Dead Zone): Total absence of lipofuscin emission appears pitch black, indicating 100% RPE death.
2. Junctional Hyperautofluorescence (The Battlefront): Bright glowing borders surrounding the black lesion indicate dying, stressed RPE cells loaded with toxic lipofuscin—predicting where the lesion will expand in the coming 12 months ($1.5\text{ to } 2.5\ \text{mm}^2\text{/year}$).