C41-12 Use of Rituximab After Cyclophosphamide in Treatment for a Patient With Refractory ANCA-associated Pulmonary Renal Syndrome

Introduction ANCA vasculitis is a common cause of pulmonary renal syndrome (PRS). The management typically involves immediate glucocorticoids, plasmapheresis, and immunosuppressive therapy. Some patients are refractory to standard therapy. We present a case of ANCA-associated PRS treated with rituximab after no improvement with cyclophosphamide and steroids. Case A 54-year-old male with history of hypertension presented with dyspnea and hemoptysis. He was found to have multifocal pneumonia and an acute kidney injury, with creatinine 1.64. Despite treatment of pneumonia, patient’s respiratory and renal function worsened. Kidney biopsy was obtained, with findings consistent with ANCA vasculitis. He was started on IV cyclophosphamide, pulse dose steroids, and avacopan. However, his respiratory status and renal function worsened. After respiratory arrest, he was intubated and initiated on ECMO on day 7 of admission. He started CRRT after labs revealed profound acidosis with lactate 7.9 and creatinine 5.82. On day 8, plasmapheresis was initiated. He received a second dose of cyclophosphamide (2 weeks after first dose) and continued a steroid taper. He stopped ECMO on day 15. Plasmapheresis was completed on day 20. However, on this day, he was extubated but had to be reintubated for hypoxia. Bronchoscopy after reintubation was consistent with Diffuse Alveolar Hemorrhage (DAH). Serial chest imaging revealed worsening infiltrates, and ventilation requirements increased. Patient’s renal function did not improve despite CRRT. During CRRT, he was unable to tolerate fluid removal due to hypotension. Given lack of response with cyclophosphamide, patient received first dose of rituximab on day 24. Despite this change, renal function did not improve. On day 30, patient had worsening respiratory acidosis and hypoxia, despite maximizing ventilator settings. The patient’s family decided to pursue comfort care, and the patient died. Discussion Given the mortality of ANCA-associated PRS, immediate initiation of steroids and immunosuppressive agents is recommended. Often cyclophosphamide or rituximab is chosen for immunosuppression. Some studies have shown promising results using both cyclophosphamide and rituximab early in the induction phase for ANCA vasculitis. However, this patient received rituximab after two doses of cyclophosphamide, steroids, plasmapheresis, and avacopan, but had no improvement. The management and timeline of refractory ANCA-associated PRS is not well-explored. Conclusion This case highlights the lack of understanding of management of refractory ANCA-associated PRS, especially in implementing a second immunosuppressant. With the high mortality of PRS, rapid, aggressive therapy of refractory disease is crucial for survival. This abstract is funded by: None