Dr Isra Iftikhar1, Dr Zhan Lim, Dr Harish Puttagunta, Dr Rebecca Hudson, Sharon Ho
1Fiona Stanley Hospital, Murdoch, Australia
Biography:
I am a second year renal advanced Trainee at Fiona Stanley Hospital with special interest in Glomerulonephritis. I also love Teaching and Education and had been the Education Registrar. Mum of four and love to cook when I have time.
Background:
Avacopan is a C5a receptor antagonist approved as adjunctive agent for treatment of anti-neutrophil cytoplasmic antibody-associated vasculitis. (AAV). We report two cases of moderate to severe thrombocytopenia after commencing Avacopan for AAV.
Case Presentation:
Case One: 83-year-old male investigated for two-week history of melaena, frank hematuria and constitutional symptoms was found to have bi-cytopenia (haemoglobin 69 g/L and platelet count of 110 × 10⁹/L), acute kidney injury and positive MPO titre (670 U/mL). Gastroscopy revealed duodenitis with chest imaging showing bilateral ground-glass infiltrates in keeping with diffuse alveolar haemorrhage. He received induction treatment with Rituximab, plasmapheresis and corticosteroids. Avacopan was commenced on day 10 with rapid steroid wean. He subsequently developed worsening thrombocytopenia (platelet nadir count 44 × 109/L), requiring Avacopan cessation and steroid reinitiating. Kidney biopsy eight-weeks post treatment showed crescentic glomerulonephritis with no active lesion and 37.5% fibrous crescents.
Case Two: A 70-year-old female was diagnosed with MPO-AAV following acute progressive renal impairment with active urinary sediment and positive MPO titre (325 U/mL) on the background of systemic sclerosis, hypertension and type II diabetes. Kidney biopsy demonstrated crescentic glomerulonephritis with 40% segmental cellular crescents. Induction therapy with rituximab and high-dose corticosteroid resulted in worsening hyperglycaemia requiring insulin. Avacopan was initiated to facilitate steroid tapering. While glycemic control has significantly improved, the patient developed thrombocytopenia (platelet nadir count 76 × 109/L) within one week of treatment.
Conclusion:
Our case series highlighted the importance of close monitoring for cytopenia during Avacopan treatment for ANCA-associated vasculitis, particularly for patients with pre-existing haematological abnormalities.