Adult onset Still's disease (AOSD) is a seronegative polyarthritis associated with rash and fever.1 The innate immune system has been implicated in its pathogenesis and hypersecretion of interleukin 1 (IL-1) has been associated with increased disease activity.2 We report the first successful use of rilonacept, a long-acting IL-1 Trap, in the management of three patients with refractory AOSD. Rilonacept is a soluble dimeric fusion protein (IL-1 receptor extracellular domain +hIgG1-Fc) administered as a weekly subcutaneous injection (220 mg loading dose and 160 mg maintenance dose).3

Patient 1 was a 41 year-old woman who presented with spiking fevers, sore throat, urticaria, arthritis and splenomegaly accompanied by leucocytosis, elevated erythrocyte sedimentation rate (>100 mm/h), increased lung function tests and hyperferritinaemia (8442 ng/ml). She …