Optimization of systemic juvenile arthritis treatment regimens with correction of tocilizumab intravenous administration according to data of observational retrospective study
Authors: Kaleda M. I. , Nikishina I. P. , Kostareva O. M. 
Published: May 2019

Objective: to assess the possibility of using varying interval between intravenous infusions of tocilizumab (TCZ) as a tool for choosing the optimal treatment regimen in systemic juvenile arthritis (SJA).

Subjects and methods. The observational retrospective study included 72 patients (29 boys and 43 girls) with a SJA fulfilled ILAR criteria, who received TCZ ≥12 months, in which previous therapy with various anti-rheumatic drugs was ineffective. We studied the changes of the main clinical and laboratory parameters of the SJA activity after correction of the interval between infusions.

Results and discussion. In the studied group median age of onset was 3.8 [2.1; 5.9] years, duration of disease before the appointment of TCZ – 26.5 [9.25; 62.25] months. Therapy is continued by 70 patients, the median duration of therapy is 5.0 [2.75; 6.38] years. The initial interval between TCZ infusions was 2 weeks in 49 (group 1) and 4 weeks in 23 patients (group 2). After 6 months of therapy in group 2, the interval was reduced to 2 weeks in 15 (65.2%) patients due to decreased effectiveness. Prolongation of the period between the introduction of TCZ in patients of group 1 who did not reach the inactive status of the disease in the 1st year of the disease resulted in a significant increase of erythrocyte sedimentation rate, C-reactive protein level and exacerbation of systemic manifestations of SJA (p<0.01) in the absence of statistically significant changes of joint status parameters (p>0.05). 40% of these patients had involvement of «new» joints, including hip joints. «Harbingers» of exacerbation in the period of increasing intervals between infusions were: arthralgia (88%), myalgia (65%), sore throat (30%), dysphoria (50%, more often in preschool children), increase of ferritin level and number of leukocytes. In 90.3% of patients who have reached the inactive status of the disease, it was possible to gradually increase the interval between infusions. In 6 patients, TCZ was canceled by gradually increasing the intervals, in 4 of them, therapy was resumed at an initial interval of 2 weeks after 3, 6, 21 and 22 months, respectively, in two patients, a drug-free remission was maintained during 23 and 20 months. Reduction of intervals to the initial 2 weeks was performed in 13 (18.1%) patients. The development of exacerbations with the need to reduce the interval to the initial one was most often observed at 24–35 months of therapy, which chronologically coincided with the period of active growth. Currently, 15 patients receiving TCZ with an interval of 5–6 weeks, and 40 – with an interval of 4 weeks, 9 patients – 3 weeks, in 6 patients attempt to increase the interval to more than 2–2,5 weeks was unsuccessful.

Conclusion. Experience suggests the need to comply with a two-week interval between infusions of TCZ at the initial stage of therapy in most patients with SJA until the inactive stage of the disease, followed by a smooth individual increase in the interval to 4 weeks (2–3 days under careful medical supervision). Appearance of initial signs of exacerbation, requires to reduce the interval to 2 weeks. Before deciding on the complete withdrawal of TCZ, it is advisable to increase the interval between infusions to 5–6 weeks under careful clinical and laboratory control.