Background
Phase III double-blind placebo-controlled RCT. 87 patients with PNH who had been transfused ≥4 times in the prior 12 months (transfusion-dependent). Randomized 1:1. Eculizumab is a humanized monoclonal antibody that binds complement C5, blocking generation of C5a and the membrane attack complex (C5b-9), thereby preventing intravascular hemolysis. First complement inhibitor approved for PNH. All patients received meningococcal vaccination ≥2 weeks prior to treatment.
Interventions and follow up
Arm A: Eculizumab 600 mg IV weekly × 4 doses, then 900 mg IV every 2 weeks
Arm B: Placebo IV on the same schedule
Primary endpoint: Hemoglobin stabilization (no transfusion AND no decrease in Hgb ≥2 g/dL from baseline) AND number of packed red cell units transfused
Median follow-up: 26 weeks
Arm B: Placebo IV on the same schedule
Primary endpoint: Hemoglobin stabilization (no transfusion AND no decrease in Hgb ≥2 g/dL from baseline) AND number of packed red cell units transfused
Median follow-up: 26 weeks
Results
Hgb stabilization: 49% (eculizumab) vs 0% (placebo), P<.001
Transfusion avoidance: 51% vs 0%
LDH reduction: 86% reduction (eculizumab) vs no change (placebo)
FACIT-Fatigue improvement: +6.4 vs −4.0 points, P<.001
Transfusion avoidance: 51% vs 0%
LDH reduction: 86% reduction (eculizumab) vs no change (placebo)
FACIT-Fatigue improvement: +6.4 vs −4.0 points, P<.001
Adverse events
Common AEs: headache most frequent (44% eculizumab vs 27% placebo); no meningococcal infections (all vaccinated)
Serious events/mortality: grade ≥3 AEs 16% (eculizumab) vs 28% (placebo); 1 infusion-related reaction (eculizumab), 3 serious AEs (placebo); no deaths in either arm during the study period
Serious events/mortality: grade ≥3 AEs 16% (eculizumab) vs 28% (placebo); 1 infusion-related reaction (eculizumab), 3 serious AEs (placebo); no deaths in either arm during the study period
Conclusions
Eculizumab eliminated transfusion requirement in 51% of patients and reduced hemolysis by 86%, establishing C5 inhibition as the standard of care for transfusion-dependent PNH with intravascular hemolysis.
Key Limitations
Short 26-week trial; long-term durability required subsequent open-label extension. Limited to transfusion-dependent patients (≥4 units/year) — SHEPHERD addressed the broader hemolytic population. ~49% of eculizumab patients still did not achieve hemoglobin stabilization. Eculizumab does not address extravascular hemolysis (C3-mediated), leading to persistent anemia in ~35% despite treatment. Lifelong IV therapy q2w is burdensome. High cost and meningococcal risk require ongoing prophylaxis.
Clinical Context
FDA approved eculizumab (Soliris) for PNH in March 2007 — the first FDA-approved complement inhibitor — transforming PNH from a life-threatening to a manageable condition. Long-term data showed reduced thrombosis (a key cause of PNH mortality), reduced kidney disease, and improved survival. Ravulizumab (q8w) later demonstrated non-inferiority with more convenient dosing. Pegcetacoplan (proximal C3 inhibitor) showed superior Hgb improvement in patients with persistent anemia (PEGASUS, 2021). Crovalimab (q4w SC) showed non-inferiority in COMMODORE 2.