Pegcetacoplan

What is Pegcetacoplan?#

Pegcetacoplan is a PEGylated cyclic peptide that inhibits complement component C3, the central protein at the convergence of all three complement activation pathways (classical, lectin, and alternative). Developed by Apellis Pharmaceuticals, it is marketed under two brand names for two distinct indications:

• Empaveli (subcutaneous injection): FDA-approved May 14, 2021 for the treatment of paroxysmal nocturnal hemoglobinuria (PNH) in adults
• Syfovre (intravitreal injection): FDA-approved February 17, 2023 as the first treatment for geographic atrophy (GA) secondary to age-related macular degeneration (AMD)

This dual-indication profile -- spanning hematology and ophthalmology -- reflects the broad pathological role of complement dysregulation across organ systems.

Mechanism of Action#

Pegcetacoplan is a second-generation compstatin derivative. Compstatins are a family of cyclic peptides that bind selectively to C3 and C3b, blocking access to C3 convertases through steric hindrance. By targeting C3, pegcetacoplan provides more comprehensive complement inhibition than C5-targeted therapies:

• All-pathway blockade: C3 is the convergence point of the classical, lectin, and alternative pathways, so C3 inhibition blocks downstream complement activation regardless of the initiating trigger
• C3 convertase inhibition: Prevents cleavage of C3 into C3a (anaphylatoxin) and C3b (opsonin and amplification loop component)
• Extravascular hemolysis control (PNH): In PNH, C5 inhibitors control intravascular hemolysis but cannot prevent C3b opsonization of red blood cells, which leads to extravascular hemolysis in the liver and spleen. C3 inhibition addresses both hemolytic mechanisms
• Complement-mediated retinal damage (GA): In geographic atrophy, complement activation contributes to progressive photoreceptor and RPE cell death. C3 inhibition reduces complement-driven tissue damage in the retina

Clinical Development#

Pegcetacoplan has an extensive clinical program spanning two therapeutic areas:

PNH Program#

• PEGASUS (Phase 3): Published in NEJM 2021, demonstrated superiority over eculizumab in hemoglobin improvement (P<0.001) with 85% of patients becoming transfusion-free
• 307 Extension Study: Confirmed long-term safety and efficacy of subcutaneous pegcetacoplan in PNH through 48+ weeks
• EU approval: Aspaveli approved December 2021 by EMA for PNH

Geographic Atrophy Program#

• OAKS and DERBY (Phase 3): Published in The Lancet 2023, demonstrated 19-22% reduction in GA lesion growth at 24 months with monthly intravitreal injection
• GALE Extension: Ongoing extension study evaluating long-term outcomes through 36 months
• EU regulatory outcome: EMA CHMP issued negative opinion for Syfovre in GA

Important Considerations#

Pegcetacoplan is an FDA-approved prescription medication with important safety considerations for both formulations:

• Empaveli (SC): Carries a boxed warning for serious infections caused by encapsulated bacteria (Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type B). Vaccination required before treatment
• Syfovre (intravitreal): Risks include endophthalmitis, retinal detachments, and a signal for increased conversion to neovascular (wet) AMD
• C3 inhibition is broader than C5 inhibition, which means more comprehensive complement blockade but also potentially greater immunosuppression
• The two formulations (SC and intravitreal) have fundamentally different pharmacokinetic profiles and safety considerations

Key Research Findings#

Pegcetacoplan versus Eculizumab in Paroxysmal Nocturnal Hemoglobinuria, published in New England Journal of Medicine (Hillmen P et al., 2021; PMID: 33730455):

• Pegcetacoplan was superior to eculizumab in hemoglobin improvement (adjusted mean difference 3.84 g/dL; P<0.001)
• 85% of pegcetacoplan patients were transfusion-free vs 15% of eculizumab patients
• C3 inhibition controlled both intravascular and extravascular hemolysis

Pegcetacoplan for geographic atrophy (OAKS and DERBY), published in The Lancet (Liao DS et al., 2023; PMID: 37865470):

• Monthly pegcetacoplan reduced GA lesion growth by 22% (OAKS) and 19% (DERBY) at 24 months vs sham
• Treatment effects increased over time with greatest benefit at months 18-24
• No improvement in visual function secondary endpoints

Related Reading#

• Pegcetacoplan research studies and evidence
• Pegcetacoplan dosing protocols
• Pegcetacoplan side effects profile
• Zilucoplan overview
• Rusfertide research guide