Longterm safety and effectiveness of the anti-interleukin 6 receptor monoclonal antibody tocilizumab in patients with systemic juvenile idiopathic arthritis in Japan.

OBJECTIVE

To assess the longterm safety and effectiveness of tocilizumab (TCZ) in systemic-onset juvenile idiopathic arthritis (sJIA).

METHODS

The longterm extension phase of 2 pivotal studies (phase II with 11 patients and phase III with 56 patients) in patients with active sJIA was analyzed. Patients received open-label TCZ (8 mg/kg, every 2 weeks) without concomitant use of disease-modifying antirheumatic drugs.

RESULTS

In total, 67 patients were enrolled. All patients received corticosteroid at baseline. Median duration of exposure to TCZ was 3.4 years. Nine patients withdrew from the study [4 because of adverse events (AE), 4 because of the development of anti-TCZ antibodies, and 1 because of inadequate response]. Rates of AE and serious AE were 803.7/100 patient-years (PY) and 34.7/100 PY, respectively. The most common serious AE were infections (13.2/100 PY). No cases of malignancy or death were reported. Two serious infusion reactions were reported in patients testing negative for anti-TCZ antibodies. One definite macrophage activation syndrome (MAS) case and 1 potential MAS case were identified. American College of Rheumatology (ACR) response rates attained early in the TCZ treatment period were maintained throughout the study: at Week 168, JIA ACR 30, 50, 70, 90, and 100 response rates were 80.3%, 80.3%, 75.4%, 60.7%, and 18.0%, respectively. In total, 22 of 67 patients (32.8%) completely discontinued corticosteroids without flare.

CONCLUSION

TCZ has demonstrated durability of effectiveness in the longterm treatment of children with sJIA and has shown good tolerability and a low discontinuation rate associated with AE, development of anti-TCZ antibodies, or inadequate response. (ClinicalTrials.gov NCT00144599 and NCT00144612). (First Release March 15 2014; J Rheumatol 2014;41:759-67; doi:10.3899/jrheum.130690).