Successful use of a humanized anti-interleukin-6 receptor antibody, tocilizumab, to treat amyloid A amyloidosis complicating juvenile idiopathic arthritis.

We report an excellent clinical response to treatment with a humanized anti-interleukin-6 receptor antibody, tocilizumab, in a patient with progressive amyloid A (AA) amyloidosis complicating very active juvenile idiopathic arthritis. Treatment with tocilizumab immediately normalized the serum AA (SAA) level, and subsequently all of the clinical symptoms of AA amyloidosis disappeared. Serial gastrointestinal biopsy specimens showed marked lasting regression of AA protein deposits. The patient's functional ability score improved dramatically, she maintains her mobility, and she has regained her previous quality of life. Tocilizumab appears to have an excellent ability to suppress SAA levels and could therefore be an important therapeutic strategy in AA amyloidosis secondary to rheumatic diseases.