Anaphylaxis to tocilizumab in patients with rheumatic disease

Lay abstract Anaphylaxis is a life-threatening allergic reaction that can be triggered by food, latex and drugs. Tocilizumab is widely used to treat rheumatic disease, including rheumatoid arthritis (RA), adult-onset Still's disease (AOSD) and Takayasu arteritis (TAK). As case reports of tocilizumab-induced anaphylaxis have previously been reported, we evaluated the incidence of anaphylaxis in patients starting tocilizumab treatment. Over the course of 6 months, four of 171 (21.4% in AOSD vs 0.7% in RA vs 0% in TAK) patients developed anaphylaxis within the third course of infusions. An AOSD patient with anaphylaxis, who presented with active disease status persistently, was successfully treated with tocilizumab again after desensitization. In conclusion, when considering tocilizumab treatment, especially in AOSD patients, we should keep in mind that intensive monitoring for anaphylaxis is necessary. Background: Anaphylaxis to tocilizumab has been reported anecdotally. Therefore, we evaluated the incidence of anaphylaxis in patients starting tocilizumab. Materials & methods: This retrospective study included patients with rheumatic disease who were administered tocilizumab from 2013 to 2020. The incidence of anaphylaxis was examined during the first 6 months. Results: During follow-up, four of 171 patients developed anaphylaxis within the third course of infusions. The incidence of anaphylaxis to tocilizumab was higher in patients with adult-onset Still's disease (AOSD) than in those with other rheumatic disease (21.4% in AOSD vs 0.7% in rheumatoid arthritis vs 0% in Takayasu arteritis). Conclusions: When we consider tocilizumab treatment, especially in AOSD, we should keep in mind that intensive monitoring for anaphylaxis is necessary.