[Tocilizumab: experience in a French rheumatological pediatric center]

Tocilizumab (TCZ) is an anti-interleukin-6-receptor antibody. The blockade of IL-6 is used as a strategy for the treatment of systemic juvenile idiopathic arthritis (S-JIA) and multicentric Castleman disease (MCD). In this study, we describe the tolerability profile of tocilizumab in eight children followed in a pediatric rheumatology department. Six patients were treated for S-JIA and two for a MCD. They received doses of TCZ between 8 and 12mg/kg of body weight depending on their disease. Infusions were received every 2-4 weeks. The mean duration of treatment was 32.9 months (14 months to 4.5 years). Clinical adverse events were all mild or moderate. No cases of macrophage activation syndrome and no anaphylactic reactions were reported. TCZ was never stopped for a clinical adverse event. Neutropenia was the most common biological adverse event, sometimes requiring dose adjustments. Thrombopenia, lymphopenia, and increased liver enzymes were reported as well, but treatment was not modified. All these biological adverse events were not complicated by any clinical manifestation. In conclusion, TCZ had a good tolerability profile in these eight patients with partial or total efficacy. Despite this advantageous profile, TCZ should be closely monitored because of the potential severity of adverse events. Moreover, long-term safety has still not been assessed.