Therapy in ESRD patients with antiphospholipid antibody syndrome

Eculizumab prevents recurrent antiphospholipid antibody syndrome and enables successful renal transplantation

Renal transplantation in patients with antiphospholipid antibodies has historically proven challenging due to increased risk for thrombosis and allograft failure. This is especially true for patients with antiphospholipid antibody syndrome (APS) and its rare subtype, the catastrophic antiphospholipid antibody syndrome (CAPS). Since a critical mechanism of thrombosis in APS/CAPS is one mediated by complement activation, we hypothesized that preemptive treatment with the terminal complement inhibitor, eculizumab, would reduce the extent of vascular injury and thrombosis, enabling renal transplantation for patients in whom it would otherwise be contraindicated. Three patients with APS, two with a history of CAPS, were treated with continuous systemic anticoagulation together with eculizumab prior to and following live donor renal transplantation. Two patients were also sensitized to human leukocyte antigens (HLA) and required plasmapheresis for reduction of donor-specific antibodies. After follow-up ranging from 4 months to 4 years, all patients have functioning renal allografts. No systemic thrombotic events or early graft losses were observed. While the appropriate duration of treatment remains to be determined, this case series suggests that complement inhibitors such as eculizumab may prove to be effective in preventing the recurrence of APS after renal transplantation.

The antiphospholipid syndrome

The antiphospholipid (aPL) antibody syndrome is an autoimmune condition in which vascular thrombosis and/or recurrent pregnancy losses occur in patients with laboratory evidence for antibodies that bind to phospholipids. There have been significant advances in the recognition of the role of phospholipid-binding cofactors, primarily beta2GPI, as the true immunologic targets of the antibodies. Recent evidence suggests that the antibodies disrupt phospholipid-dependent anticoagulant mechanisms and/or that aPL antibodies induce the expression of procoagulant and proadhesive molecules on endothelial cells. Current diagnosis is based on clinical findings and empirically derived tests, such as assays for antibodies that bind to phospholipids or putative cofactors and coagulation assays that detect inhibition of phospholipid-dependent coagulation reactions. Current treatment relies primarily on anticoagulant therapy. Research advances are expected to bring mechanistically based diagnostic tests and improved therapy that target the roots of the disease process.

Nephrological and obstetric complications of the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a disorder of hypercoagulability, characterised by thromboembolic events, repeated miscarriages and thrombocytopenia in association with circulating antiphospholipid antibodies. These antibodies are directed against epitopes on either oxidised phospholipids complexed with a glycoprotein, beta 2-glycoprotein I, or against the glycoprotein itself. Renal manifestations of the APS are varied and depend on the type of renal pathology present. The renal vasculature may be affected by either a small vessel, thrombotic microangiopathy process or by large vessel thrombosis. In patients with end stage renal disease, the prevalence of antiphospholipid antibodies may increase with time on dialysis. Anticardiolipin antibodies have been associated with a high incidence of haemodialysis access clotting, a major source of morbidity and hospitalisation in end stage renal disease patients. In renal transplant recipients, antiphospholipid antibodies may be associated with a higher incidence of primary graft non-function, particularly in patients without a history of pretransplantation haemodialysis. Complications of the APS during pregnancy span all trimesters and include intrauterine growth retardation, placental abruption, pre-eclampsia, preterm labour and recurrent fetal loss. As these women have a high risk of recurrent fetal loss, multiple treatment modalities have been investigated, including aspirin, heparin, prednisone and intravenous immunoglobulin. Various treatment strategies for the APS have been developed and are based on a combination of anticoagulant therapy with either warfarin or heparin, along with antiplatelet therapy with aspirin. Experimental treatments involving immunomodulatory therapy with intravenous immunoglobulin, apheresis and novel antibody therapy are being investigated with hopes of successful clinical applications.