What is appropriate treatment to maintain remission in Granulomatosis with polyangiitis?
• Since it is extremely common for GPA to relapse (especially when PR3-ANCA is positive), some form of maintenance therapy is standard.
• If a patient with generalized GPA has been brought into remission using cyclophosphamide in combination with prednisone, they should be switched to another less toxic immunosuppressive medication such as azathioprine, methotrexate (if renal function is acceptable), or rituximab . This usually can occur within 3 to 6 months after starting cyclophosphamide.
• Several medications have been used to maintain remission including azathioprine, methotrexate, mycophenolate mofetil, and leflunomide. Clinical trials have demonstrated similar efficacy of azathioprine and methotrexate, while one study has suggested less benefit with mycophenolate in comparison to azathioprine.
• Rituximab maintenance therapy is also effective, with data demonstrating superiority over an azathioprine maintenance regimen (MAINRITSAN trial). The optimal dose and interval have not been established, but this trial utilized a regimen of 500 mg every 6 months. A more recent study suggests that retreatment with rituximab for maintenance therapy may be done less frequently based upon a rise in ANCA titer or transition from negative to positive ANCA status, or reappearance of B-cell counts (MAINRITSAN2). Further investigation into optimal redosing strategies is needed.
• The duration a GPA patient should remain on maintenance therapy is unclear. Patients who have been in complete remission for 12 to 18 months on standard maintenance therapy have a 50% risk of relapse once that therapy is stopped. A recent study has shown that maintenance therapy for over 36 months is associated with less chance of relapse, suggesting that maintenance therapy may be needed indefinitely in some patients.
• With modern therapies, the 5-year survival rate is 85% to 90%.
