A 72-year-old woman from Delhi with a 15-year history of rheumatoid arthritis (RA) on methotrexate presents with nephrotic syndrome (serum albumin 2.1 g/dL, 24-hour urine protein 8.5 g). Renal biopsy shows amyloid deposits with Congo red positivity and mass spectrometry confirms AA amyloidosis. Her RA is currently well-controlled (CRP 0.8 mg/dL, ESR 12 mm/hr). What is the most appropriate next step in management?