Background/Purpose: Elevated interleukin-6 (IL-6) levels have been associated with low growth velocity in patients with juvenile idiopathic arthritis (JIA).¹ The efficacy of tocilizumab (TCZ), an IL-6 receptor inhibitor, in patients with polyarticular-course JIA (pcJIA) was demonstrated up to 104 weeks in the phase 3 CHERISH trial.² Growth was evaluated in patients with pcJIA treated with TCZ for up to 104 weeks in CHERISH.

Methods: Patients with active pcJIA for ≥6 months and inadequate responses to methotrexate received open-label (OL) TCZ intravenously every 4 weeks (randomly assigned 1:1 to receive 8 or 10 mg/kg for body weight [BW] <30 kg or 8 mg/kg for BW ≥30 kg) for 16 weeks. At week 16, patients with ≥JIA ACR30 response were randomly assigned 1:1 to receive placebo or to continue TCZ double-blind for 24 weeks. At week 40, all patients entered an OL extension and received TCZ according to BW through week 104. Height velocity and height standard deviation scores (SDS) were measured in patients with Tanner stage <4 (the subset of study patients with the highest growth potential) provided they did not receive the growth hormone somatotropin during the study.

Results: Of 188 patients who received ≥1 dose of TCZ, 123 patients with Tanner stage <4 were included in the growth population (1 patient received somatotropin and was excluded from the growth population). At baseline, the growth population had a mean World Health Organization (WHO) height SDS ± SD of –0.5 ± 1.2. The baseline height SDS was not related to age or disease duration (Spearman’s rank correlations r = 0.08 and r = –0.12, respectively). For patients with Tanner stage <4 at baseline and height data at year 2 of the study (n = 103), baseline mean height SDS increased significantly (by 0.40) from baseline to year 2 of treatment (p < 0.0001 vs baseline). At year 2, 71.8% (74/103) of these patients had an increased height SDS compared with their baseline height SDS, with a mean height velocity of 6.7 ± 2.0 cm/year (n = 103). For patients with available data at year 2 (n = 103), the mean daily oral corticosteroid doses (± SD) at baseline and year 2 of treatment were 0.05 mg/kg (± 0.08) and 0.02 mg/kg (± 0.05), respectively.

Conclusion: Mean height SDS of patients with pcJIA was below normal at baseline. The majority of patients who were Tanner stage <4 at baseline (71.8%) had an increased height SDS at year 2 (end of study). 

References: 1. Souza LS et al J Rheumatol. 2008;35:2265-2271. 2. Brunner HI et al Arthritis Rheumatol. 2013:65(suppl):S335.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/growth-during-tocilizumab-therapy-for-polyarticular-course-juvenile-idiopathic-arthritis-2-year-data-from-a-phase-3-clinical-trial/