Growth during tocilizumab therapy for polyarticular-course juvenile idiopathic arthritis: 2-year data from a phase III clinical trial

Objective: Evaluate growth in patients with polyarticular-course juvenile idiopathic arthritis (pcJIA) treated with tocilizumab (TCZ) for up to 2 years in a phase III trial. Methods: Patients with pcJIA lasting at least 6 months and inadequate response to methotrexate received open-label TCZ intravenously every 4 weeks (randomly assigned to 8 or 10 mg/kg if they weighed < 30 kg; received 8 mg/kg if they weighed ≥ 30 kg) for 16 weeks. Patients with JIA American College of Rheumatology 30 response at Week 16 were randomly assigned to TCZ or placebo for 24 weeks, with an open-label extension through Week 104. Mean ± SD height velocity (cm/yr) and World Health Organization (WHO) height SD score (SDS) were measured in patients receiving ≥ 1 dose of TCZ who did not receive growth hormone and in patients whose baseline Tanner stage was ≤ 3. Results: The study included 187 of 188 patients (99.5%) with mean WHO height SDS -0.5 ± 1.2, which was unrelated to age or disease duration (Spearman rank correlations r = 0.08 and r = -0.12, respectively). There were 123 patients at Tanner stage ≤ 3 at baseline, among whom 103 completed the study with 2 years of height SDS data. Mean height SDS increased from baseline to year 2 (+0.40, p < 0.0001). In 74 of 103 patients (72%), height SDS was greater than at baseline, and mean height velocity was 6.7 ± 2.0 cm/year. Conclusion. Among patients with pcJIA at Tanner stage ≤ 3 at baseline, 72% (74/103) had increased height SDS at the end of the study.