C3 Glomerulopathy and Therapeutic Potential of C5 Complement Inhibitors

Abstract

C3 glomerulopathy is a disease including both dense deposit disease and C3 glomerulonephritis has an estimated prevalence of 2 to 3 per million. Originally, these pathologies were defined as glomerular pathology characterized by accumulation of C3 with absent or scanty immunoglobulin deposition. The keystone defect in both of these pathologies is the unregulated hyperactivity of alternative complement pathway. Specifically, in C3 glomerulopathy patients, there exists a prolongation of C3 cleavage which causes the uncontrolled alternative pathway activation. Many treatments have been investigated for treating C3 glomerulopathy to little or no avail, including calcineurin inhibitors, plasmapharesis, and anti-CD20 monoclonal antibodies. The next logical step is exploring the efficacy of anti-C5 monoclonal antibody therapy in C3 glomerulopathies to target the specific pathophysiology of this particular disease. Eculizumab is an anti-C5 monoclonal antibody that blocks the terminal step of complement activation. This drug has proven to be an effective treatment in other nephrologic pathologies that are caused by complement dysregulation. Here in this paper we discuss and present various case studies and clinical trials available that experiment with Eculizumab in patients with either dense deposit disease or C3 glomerulonephritis. In most of these patients, treatment with Eculizumab has demonstrated clinical and biochemical improvements in kidney function. These results provide encouraging evidence that suggest Eculizumab as a promising therapy for patients with C3 glomerulopathy and warrant that more extensive clinical trials can be designed as a next step.