What is the treatment for mild Microscopic Polyangiitis (MPA)?

From the Guidelines

The treatment for mild Microscopic Polyangiitis (MPA) typically involves a combination of glucocorticoids and immunosuppressive medications, with a recommended initial therapy of oral prednisone at 1 mg/kg/day (maximum 60-80 mg daily) combined with either oral methotrexate (15-25 mg weekly) or oral mycophenolate mofetil (1-3 g daily in divided doses) 1. The choice of immunosuppressant may depend on patient-specific factors, such as contraindications or preferences.

• Methotrexate is a commonly used immunosuppressant for MPA, with a recommended dose of up to 25 mg/week (SC or oral) 1.
• Mycophenolate mofetil is another option, with a recommended dose of up to 1,500 mg (oral) twice per day 1.
• Azathioprine may be used as an alternative immunosuppressant, with a recommended dose of up to 2 mg/kg/day 1. Regular monitoring of complete blood counts, kidney function, and urinalysis is essential to assess treatment response and detect potential medication side effects 1. Patients should also receive Pneumocystis pneumonia prophylaxis with trimethoprim-sulfamethoxazole (one single-strength tablet daily or one double-strength tablet three times weekly) while on immunosuppressive therapy. Calcium and vitamin D supplementation should be considered to prevent glucocorticoid-induced osteoporosis. This treatment approach aims to suppress the abnormal autoimmune response and vasculitis that characterize MPA, reducing inflammation in small blood vessels and preventing organ damage 1.

From the FDA Drug Label

In the 6-month remission induction phase, 197 patients with GPA and MPA were randomized to either RITUXAN 375 mg/ m2 once weekly for 4 weeks plus glucocorticoids, or oral cyclophosphamide 2 mg/kg daily (adjusted for renal function, white blood cell count, and other factors) plus glucocorticoids to induce remission The primary analysis was at the end of the 6 month remission induction period and the safety results for this period are described below The main outcome measure for both GPA and MPA patients was achievement of complete remission at 6 months defined as a BVAS/GPA of 0, and off glucocorticoid therapy The study demonstrated non-inferiority of RITUXAN to cyclophosphamide for complete remission at 6 months

The treatment for mild Microscopic Polyangiitis (MPA) is not explicitly stated in the provided drug labels. However, for active GPA and MPA, the treatment options include:

• RITUXAN 375 mg/m2 once weekly for 4 weeks plus glucocorticoids
• Oral cyclophosphamide 2 mg/kg daily (adjusted for renal function, white blood cell count, and other factors) plus glucocorticoids It is essential to note that these treatments are for active disease, and the labels do not provide specific guidance for mild MPA. Therefore, the treatment for mild MPA cannot be determined based on the provided information 2 2.

From the Research

Treatment for Mild Microscopic Polyangiitis (MPA)

The treatment for mild MPA typically involves the use of immunosuppressive medications to induce and maintain remission. Some of the key treatment options include:

• Mycophenolate mofetil (MMF) combined with corticosteroids, which has been shown to be effective in inducing remission in patients with MPA 3, 4
• Cyclophosphamide (CYC) plus corticosteroids, which is considered standard therapy for patients with renal involvement, but may have significant toxicity 3, 5
• Glucocorticoids plus MMF regimen, which has been shown to achieve high remission rates and good long-term renal survival in patients with mild to moderate renal involvement 6

Key Considerations

When treating mild MPA, it's essential to consider the following:

• The severity of renal involvement, as this can impact treatment outcomes 3, 6
• The presence of other systemic symptoms, such as lung involvement or musculoskeletal symptoms 5
• The potential for relapse, which can occur in up to 22.6% of patients 6
• The need for long-term maintenance therapy to prevent relapse and maintain remission 7

Treatment Outcomes

Studies have shown that treatment with MMF and corticosteroids can lead to:

• High remission rates, with up to 91.2% of patients achieving remission 6
• Improved renal function, with stable or improved eGFR levels 3, 4
• Reduced disease activity, as measured by the Birmingham vasculitis activity score (BVAS2) 7
• Low toxicity, with few adverse events reported 3, 7