Effective therapy of tocilizumab on systemic juvenile idiopathic arthritis--associated refractory macrophage activation syndrome.

Objectives: To evaluate the safety and efficacy of tocilizumab (TCZ) on refractory macrophage activation syndrome (rMAS) associated with systemic juvenile idiopathic arthritis (sJIA-rMAS). Methods: We retrospectively reviewed the charts of 14 patients diagnosed with sJIA-rMAS, who were treated with TCZ after failing conventional therapies at three hospital centres from January 2016 to December 2020. Demographic, clinical, and laboratory characteristics were recorded at the onset of MAS, before TCZ (pre-TCZ), and 14 days after TCZ (post-TCZ). Results: The clinical manifestation of sJIA-rMAS included fever (100%), skin rashes (35.7%), lymphadenomegaly (42.9%), hepatomegaly (57.1%), splenomegaly (7.1%), gastrointestinal symptoms (28.6%), arthritis (14.3%), myalgia (28.6%), and polyserositis (14.3%). After TCZ treatment, fever (100%, 14/14), gastrointestinal symptoms (100%, 4/4), and myalgia (100%, 4/4) were significantly improved after 1 week (P< 0.05). Skin rashes, lymphadenomegaly, and arthritis also improved in many patients, but these parameters did not reach statistical significance. In post-TCZ group, decreases in levels of C-reactive protein, erythrocyte sedimentation rate, and serum ferritin of sJIA-rMAS were observed compared with pre-TCZ (P< 0.05). No disease relapse or fatality was recorded during the follow-up (25 months, range 3-60 months). Conclusions: TCZ is safe and effective for the treatment of sJIA-rMAS after failure of conventional therapies. [ABSTRACT FROM AUTHOR]