#2698 Regression of amyloid deposits after treatment with tocilizumab

Abstract Background and Aims AA amyloidosis is a multisystem disease characterized by the deposition of serum amyloid A protein, which is secondary to chronic inflammation. Tocilizumab (an interleukin-6 inhibitor monoclonal antibody) is effective in suppressing inflammation, normalizing serum amyloid A protein levels and inducing remission in patients with amyloidosis. Recently, tocilizumab treatment has been associated with the disappearance of amyloid deposits. Results We report a case of AA amyloidosis secondary to chronic arthritis in a 61-year-old woman referred to our hospital in 2011 due to oligoarthritis of the knees and elevation of acute-phase reactants. Corticosteroids and methotrexate were prescribed, without clinical response. Two years later, the patient presented with foamy urine, nocturia, sweating and dizziness. An elevated C-reactive protein (CRP), erythrocyte sedimentation rate and nephrotic-range proteinuria were found. Rectal and oral mucosa biopsies were performed and amyloid AA deposits were detected in both (Fig. 1A, B). Magnetic resonance imaging (MRI) of the right knee showed arthropathy due to amyloid deposition (Fig. 2). Intravenous monthly tocilizumab was prescribed with rapid improvement of CRP, proteinuria (Fig. 3) and nephrotic syndrome symptoms. Arthritis also improved significantly. Two years later, a new biopsy of the rectal mucosa did not show amyloid deposits (Fig. 1C, D) and right knee MRI was normal, without evidence of amyloid synovitis (Fig. 4). Eight years later, the patient continues treatment with tocilizumab and remains clinically stable, with no evidence of recurrence. Literature review: The efficacy of tocilizumab has been described mainly in patients with rheumatoid arthritis, but also in AA amyloidosis secondary to systemic juvenile idiopathic arthritis, familial Mediterranean fever, psoriatic arthritis, ankylosing spondylitis, Still's disease, Muckle-Wells syndrome, Behçet syndrome, polyarteritis nodosa and Takayasu arteritis. Some of the studies report long-term effectiveness of up to 9 years. In 11 case reports of patients with AA amyloidosis treated with tocilizumab, a follow-up biopsy was performed and a reduction or disappearance of the deposits was also observed. Lane et al. analyzed pre- and on-treatment serial scintigraphy scans in 20 patients with AA amyloidosis, showing that AA amyloid deposits either regressed or did not increase whilst on tocilizumab. We have not identified any study demonstrating the disappearance of amyloid arthropathy in MR images. Conclusion Tocilizumab treatment controls chronic inflammatory disease and improves symptoms of AA amyloidosis. Long-term treatment with tocilizumab may remove amyloid deposits from tissues, leading to a definitive cure of this disease.