Antiphospholipid syndrome (APS) is characterized by arterial and/or venous thrombosis with antiphospholipid antibodies. Dysregulation of the complement pathway has been implicated in APS pathophysiology. We report successful use of eculizumab, an anti-C5 monoclonal antibody, in controlling and preventing recurrent thrombosis in a refractory case of APS. An 18-year-old female was diagnosed with APS after developing extensive unprovoked deep vein thrombosis of axillary, inferior vena cava and brachiocephalic veins. Thrombophilia evaluation revealed triple positive lupus anti-coagulant, beta-2 glycoprotein IgM, IgA and anti-cardiolipin antibodies (each >40U/mL) with persistently positive titers after 12 weeks. She was refractory to multiple anticoagulants alone (enoxaparin, fondaparinux, apixaban, rivaroxaban, and warfarin) with antiplatelet (aspirin and clopidogrel) and adjunctive therapies (hydroxychloroquine, immunosuppression with steroids and rituximab, and plasmapheresis). Despite these, she continued to develop recurrent thrombosis, and additionally developed hepatic infarction and pulmonary embolism with failure to decrease titers after 6 weeks of plasma exchange. Following this event, eculizumab (600mg weekly x 4 weeks followed by 900mg every 2 weeks) was initiated in combination with fondaparinux, aspirin, clopidogrel and hydroxychloroquine. She has remained on this regimen without recurrence of thrombosis. Our case suggests that eculizumab may have a role as a therapeutic option in refractory thrombosis in APS.
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