NEW RESEARCH has demonstrated that patients with juvenile idiopathic arthritis treated with tofacitinib show normal, or greater-than-expected, growth rates during long-term follow-up, with evidence of catch-up growth during puberty and no concerning changes in growth hormone biomarkers.
Long-Term Growth Concerns in Juvenile Idiopathic Arthritis
Growth impairment is a recognised complication of juvenile idiopathic arthritis because chronic inflammation can interfere with normal development during childhood and adolescence. Although tofacitinib is increasingly used in polyarticular-course juvenile idiopathic arthritis, concerns have remained regarding its potential impact on growth because of moderate Janus kinase 2 inhibition affecting growth hormone pathways.
Post Hoc Analysis of Tofacitinib Treatment Programme
This post hoc analysis evaluated children and adolescents enrolled in the tofacitinib juvenile idiopathic arthritis development programme. The study included 225 patients, predominantly with polyarticular-course juvenile idiopathic arthritis, receiving long-term tofacitinib therapy with median follow-up of 3.6 years (interquartile range 1.9 to 4.6 years). Biomarker analyses were conducted in serum samples from 137 patients completing 18 weeks of open-label tofacitinib treatment.
Growth Velocity Remained Normal During Treatment
Baseline height distribution in juvenile idiopathic arthritis patients was similar to the general population. During tofacitinib treatment, patients aged 12 years or younger experienced height velocities appearing greater than expected for age, while patients older than 12 years demonstrated expected growth velocities relative to reference populations. Height Z-scores remained largely stable during treatment. Among patients in puberty with baseline height Z-scores below −1.0, significant increases in height Z-scores were observed after 24 months of therapy (P<0.05), consistent with catch-up growth. Tofacitinib did not affect insulin-like growth factor 1, insulin-like growth factor binding protein 3, or osteocalcin levels in the overall cohort. However, insulin-like growth factor 1 increased from baseline to 18 weeks in patients aged 6 to 12 years. Confidence intervals were not reported.
Implications for Long-Term Paediatric Treatment
These findings suggest that long-term tofacitinib treatment does not adversely affect growth in juvenile idiopathic arthritis and may support catch-up growth during puberty in some patients. Researchers noted the results provide reassurance regarding growth hormone signalling and skeletal development, while supporting continued investigation of long-term safety outcomes in paediatric rheumatology populations.
Reference
Brunner HI et al. Impact of tofacitinib on growth in patients with juvenile idiopathic arthritis. Annals of the Rheumatic Diseases. 2026;DOI:10.1016/j.ard.2026.03.030.
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