Abstract
Cold agglutinin disease (CAD) is a complement-dependent disorder, with extravascular and intravascular hemolysis resulting from initial or terminal complement activation, respectively. We tested the efficacy and safety of eculizumab, an inhibitor of the terminal complement pathway. Treatment-requiring patients received 600 mg eculizumab weekly for 4 weeks, followed 1 week later by 900 mg every other week through week 26. The primary end point was the difference in the lactate dehydrogenase level between the first and the last day of therapy. Twelve patients with chronic CAD and 1 patient with an acute cold agglutinin syndrome were included. The median lactate dehydrogenase level decreased from 572 U/L (interquartile range [IQR], 534-685) to 334 U/L (IQR, 243-567; P = .0215), paralleled by an increase in hemoglobin from 9.35 g/dL (IQR, 8.80-10.80) to 10.15 g/dL (IQR, 9.00-11.35; P = .0391; Wilcoxon signed-rank test). Three patients maintained and 8 patients acquired transfusion independence, and 1 patient each showed a reduced or increased transfusion requirement, respectively (P = .0215; exact McNemar's test). Patients with cold agglutinins with a thermal amplitude of 37°C tended to have less pronounced lactate dehydrogenase responses than patients with cold agglutinins with narrower thermal amplitudes. In the latter, responses were observed at lower serum levels of eculizumab than they were in the former. In contrast to hemolysis, cold-induced circulatory symptoms remained unaffected. In conclusion, eculizumab significantly reduced hemolysis and transfusion requirement in patients with CAD. Suppression of hemolysis caused by cold agglutinins with a wide thermal amplitude may require higher eculizumab doses than used here. The trial is registered with EudraCT (#2009-016966-97) and www.clinicaltrials.gov (#NCT01303952).