Studying the Role of C5-Inhibition Therapy in Scleroderma Renal Crisis-Induced Thrombotic Microangiopathy - A Review of Literature

Background: The pathogenesis of scleroderma renal crisis (SRC) remains poorly understood but a growing body of evidence suggests that activation of the complement system may be involved in the disease. Recent studies have shown that Eculizumab (monoclonal antibody directed against the complement component C5) is effective in treating patients with SRC who present with symptoms of thrombotic microangiopathy (SRC-TMA). Objectives: In this study, we conducted a systematic review to characterize the published experience of the presentation and outcome of patients with SRC who were treated with C5 inhibitor, Eculizumab. Methods: A literature search was conducted from inception to December 2022 using Medical Subject Headings (MeSH) terms for 'scleroderma', 'scleroderma renal crisis, and 'Eculizumab'. We included case reports, case series, and observational studies which reported the use of Eculizumab with or without Angiotensin-converting enzyme inhibitors (ACE-I) for the treatment of scleroderma renal crisis (SRC) in patients with systemic sclerosis. Results: The study included 17 patients, all of whom were treated with Eculizumab. Additionally, the use of ACE-I was reported in 11/17 (64.7%) patients. Further, plasmapheresis was used in 9/17 (52.9%), steroids in 5/17 (29.4%), cyclophosphamide in 3/17 (17.6%), calcium channel blockers in 3/17 (17.6%), and Rituximab in 3/17 (17.6%) patients. Renal replacement therapy was required in 11/17 (64.7%) patients. 14/17 patients (82.3%) were reported to have clinical (renal or hematologic) improvement with Eculizumab therapy (Table 1). Conclusion: These findings should prompt testing on a larger cohort of SRC-TMA patients. This would help us determine whether aggressive treatment combining ACE-I and Eculizumab can target the various underlying endothelial, inflammatory, and immunologic mechanisms involved in SRC-TMA, and improve patient outcomes.