A 44-week, 2-part study (consisting of an 18-week, open-label, run-in phase, followed by a 26-week double-blind, placebo-controlled, randomized phase) in patients 2 to <18 years of age with pJIA (including RF positive or RF negative polyarthritis, extended oligoarthritis, systemic JIA with active arthritis and no current systemic symptoms) and patients 2 to <18 with jPsA and ERA. However, the pJIA efficacy population only includes the subgroups with either RF positive or RF negative polyarthritis or extended oligoarthritis; inconclusive results have been seen in the subgroup of patients with systemic JIA with active arthritis and no current systemic symptoms. Patients with juvenile PsA are included as separate efficacy subgroup. ERA patients are not included in the efficacy analysis.^1,2

A total of 225 patients were enrolled in the 18-week open-label run-in phase and received XELJANZ/XELJANZ Oral Solution dosed at 5 mg BID or body weight-based equivalent BID. Only patients who achieved at least a JIA ACR30 response at the end of the run-in phase (week 18) were randomized (1:1) to the double-blind phase. 173 patients (77%) met this criterion and were randomized into the double-blind phase to either XELJANZ/XELJANZ Oral Solution dosed at 5 mg BID or body weight-based equivalent BID (n=88) or placebo (n=85) for 26 weeks. Treatment with MTX was permitted but was not required during the study.¹ 

The primary endpoint was JIA flare rate by week 44. Flare is defined as a worsening of ≥30% in ≥3 of the 6 variables of the JIA core set, with ≤1 variable improving by ≥30%.²