Study of Pegloticase (KRYSTEXXA®) Plus Methotrexate in Patients With Uncontrolled Gout

pegloticase administered intravenously (IV)

oral MTX

It is required that before a subject begins the Pegloticase + IMM Period, he or she has been taking at least one protocol standard gout flare prophylaxis regimen (i.e. colchicine and/or nonsteroidal anti-inflammatory drugs and/or low-dose prednisone ≤10 mg/day) for ≥1 week before the first dose of pegloticase and continues flare prophylaxis per American College of Rheumatology guidelines \[Khanna D et al.2012\] for the greater of 1) 6 months, 2) 3 months after achieving target serum urate (sUA \< 6 mg/dL) for patients with no tophi detected on physical exam, or 3) 6 months after achieving target serum urate (sUA \< 5 mg/dL) for patients with one or more tophi detected on initial physical exam that have since resolved.

For IR prophylaxis, fexofenadine (60 mg or 180 mg orally based on the Principal Investigator's discretion) will be taken the day before each infusion; fexofenadine (60 mg or 180 mg orally based on the Principal Investigator's discretion) and acetaminophen (1000 mg orally) will be taken the morning of each infusion; and methylprednisolone (125 mg IV) given over the infusion duration 10-30 minutes (recommended) or hydrocortisone (200 mg IV) will be administered immediately prior to each infusion.

Subjects will also take folic acid 1 mg orally every day beginning at Week -4 (the start of MTX) and continuing until prior to the Week 52 Visit.