Inclusion Criteria:

1. Established diagnosis of granulomatosis with polyangiitis (GPA) where patients will need to meet at least 2 of the 5 for the classification of GPA, at least one of which must be criterion d or e:

   The modified American College of Rheumatology (ACR) criteria are:

   A. Nasal or oral inflammation, defined as the development of painful or painless oral ulcers or purulent or bloody nasal discharge.

   B. Abnormal chest radiograph, defined as the presence of nodules, fixed infiltrates, or cavities.

   C. Active urinary sediment, defined as microscopic hematuria (>5 red blood cells per high power field) or red blood cell casts.

   D. Granulomatosis inflammation on biopsy, defined as histologic changes showing granulomatous inflammation within the wall of an artery or in the perivascular or extravascular area. Note: Pauci-immune glomerulonephritis seen on kidney biopsy will suffice for this criterion.

   E. Positive anti-neutrophil cytoplasmic antibody (ANCA) test specific for proteinase-3 measures by enzyme-linked immunoassay.

   Patients who are myeloperoxidase (MPO) positive or ANCA negative are still eligible for this study if they meet the criteria above and are felt to have GPA.

2. Active disease within the prior 12 months (initial presentation or relapse) that at time of active disease required treatment with prednisone >20 mg/day.
3. Disease remission at time of enrollment.
4. Prednisone dose at time of enrollment of ≥ 5 mg/day and ≤ 20 mg/day.
5. Participant age of 18 years or greater.
6. If the patient is taking an immunosuppressive medication agent other than prednisone (maintenance agent) then the maintenance agent must be at a stable dose for one month prior to enrollment with no plans by the treating physician to change the dose (other than for safety purposes/toxicity) for the duration of the study (through the month 6 visit or early termination). Acceptable maintenance agents include azathioprine, leflunomide, 6-mercaptopurine, methotrexate, mycophenolate mofetil, or mycophenolate sodium. Patients may be on trimethoprim/sulfamethoxazole (TMP/SMX) for use as either a maintenance agent or for prophylaxis for infection. TMP/SMX may be used in combination with other drugs.

•  Rituximab is an acceptable maintenance agent if the last dose was given at least one month prior to enrollment and no additional doses are planned) for the duration of the study (through the month 6 visit or early termination). If a patient received rituximab and was then prescribed another maintenance agent, the patient is eligible if there are no plans by the treating physician to change the dose of the maintenance (other than for safety purposes/toxicity) for the duration of the study (through the month 6 visit or early termination).
•  If the patient is regularly taking trimethoprim/sulfamethoxazole at any dose then the patient is eligible if there no plans by the treating physician to change the dose after enrollment (other than for dose reduction or discontinuation for safety purposes/toxicity) for the duration of the study.

Exclusion Criteria:

1. Comorbid condition that has moderate likelihood of requiring a course of prednisone within one year of enrollment (e.g. chronic obstructive pulmonary disease (COPD), asthma, adrenal insufficiency).