Efficacy and safety of avacopan in Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis: A subanalysis of a randomized Phase 3 study

Early transition to avacopan from glucocorticoids applied during induction therapy for microscopic polyangiitis with rapidly progressive glomerulonephritis

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a systemic autoimmune disease characterized by necrotizing inflammation of small blood vessels. Glucocorticoids (GC) in combination with rituximab or cyclophosphamide can reduce AAV-related mortality and rescue renal function. However, several side effects associated with these agents, including GC toxicity, are concerning. Avacopan, an inhibitor of the C5a receptor, is now available for AAV treatment and is expected to mitigate GC toxicity. We present a case of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive microscopic polyangiitis (MPA) with rapidly progressive glomerulonephritis treated with an early switch from GC to avacopan in combination with rituximab during induction therapy. Over a 6-month treatment period, clinical remission was achieved and maintained without infection or elevated liver enzyme levels. Efficacy and safety data regarding avacopan for AAV induction therapy remain limited. Therefore, more case reports are required to clarify the role of avacopan in AAV induction and maintenance therapy. Since the MPO-ANCA titer remained elevated despite the clinical remission of AAV in this case, the ANCA titer may not necessarily be a reliable biomarker for predicting AAV relapse when avacopan is applied as an induction therapy for AAV.

Complements and Their Role in Systemic Disorders

The complement system is critical to the body's innate defense against exogenous pathogens and clearance of endogenous waste, comprising the classical, alternative, and lectin pathways. Although tightly regulated, various congenital and acquired diseases can perturb the complement system, resulting in specific complement deficiencies. Systemic rheumatic, neurological, ophthalmological, renal, and hematological disorders are some prototypical complement-mediated diseases. An adequate understanding of the mechanisms of the normal complement system and the pathophysiology of complement dysregulation is critical for providing diagnostic clues and appropriately managing these conditions. This review guides clinicians in understanding the role of complement factors in systemic diseases and what diagnostic and therapeutic options are available for complement-mediated disorders.

Synthetic Approaches to the New Drugs Approved During 2021

Each year, new drugs are introduced to the market, representing structures that have affinity for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates, provide insight into molecular recognition and serve as potential leads for the design of future medicines. This annual review is part of a continuing series highlighting the most likely process-scale synthetic approaches to 35 NCEs that were first approved anywhere in the world during 2021.

Thrombocytopenia during avacopan administration: A case report

Avacopan is a novel C5a receptor antagonist recently approved for the treatment of microscopic polyangiitis and granulomatosis with polyangiitis. To our knowledge, thrombocytopenia induced by avacopan has not been reported. We report a case of a 78-year-old man with microscopic polyangiitis who developed rapidly progressive glomerulonephritis (RPGN) and vasculitis neuropathy. After developing RPGN, he was treated with prednisolone, which was ineffective. As the dosage of corticosteroids was decreased, he developed impaired dorsiflexion of the left ankle, tingling and numbness in his feet, consistent with vasculitis neuropathy. After a 3-day administration of methylprednisolone, we started avacopan and prednisolone 20 mg/d to reduce the corticosteroid dosage. One week after starting avacopan, platelet counts began to decrease, eventually leading to the cessation of the drug. The possibility of thrombotic microangiopathy and heparin-induced thrombocytopenia was considered unlikely given the clinical course and laboratory studies. After 3 weeks of avacopan cessation, platelet counts began to increase, suggesting avacopan as the most probable cause of thrombocytopenia. Our case highlights the importance of postmarketing surveillance of avacopan to identify its adverse events that were not reported in clinical trials to ensure its safe use. Clinicians should carefully monitor platelet counts when using avacopan.