Rapid and sustained response to tocilizumab, anti-interleukin-6 receptor antibody, in a patient with nephrotic syndrome secondary to systemic juvenile idiopathic arthritis-related amyloidosis.

AA amyloidosis, or secondary amyloidosis, is a rare but serious complication of chronic inflammatory diseases. Chronic inflammatory arthritis is the commonest cause of AA amyloidosis and, when the latter appears, treatment can be frustrating. Deposition of fibrils, derived from circulating acute-phase reactant serum amyloid A protein (SAA), in the kidneys can lead to proteinuria and progressive loss of renal function. We describe the case of a 14-year-old female with systemic juvenile idiopathic arthritis who developed nephrotic syndrome secondary to AA amyloidosis; while she was unresponsive to all measures, including anti-tumour necrosis factor therapy, treatment with tocilizumab, an anti-human interleukin-6 receptor antibody, immediately normalized the SAA and reversed the nephrotic syndrome. We discuss this new therapeutic approach.