Failure of tocilizumab in treating two patients with refractory SAPHO syndrome: a case report.

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare autoinflammatory disease with no standard treatment. Interleukin (IL)-6 inhibitors represent a novel therapeutic option for rheumatoid arthritis and some autoinflammatory diseases. However, the clinical utility of IL-6 inhibitors in treating SAPHO syndrome has been poorly investigated. In the present report, we describe two patients with SAPHO syndrome that was unresponsive to conventional treatment. Tocilizumab, an anti-IL-6 receptor monoclonal antibody, was putatively administered according to positive IL-6 immunohistochemical staining in biopsied bone tissues. However, the disease continued to progress, and new-onset or worsening skin lesions were noted with transient neutropenia. These cases demonstrate that tocilizumab may not be an ideal option for treating SAPHO syndrome.