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TOPLINE:

Patients with juvenile idiopathic arthritis (JIA) who received long-term tofacitinib treatment had height velocities that appeared greater than expected in those aged 12 years or younger and were as expected in those older than 12 years, relative to reference populations.

METHODOLOGY:

• Researchers conducted a post hoc analysis to evaluate the long-term impact of tofacitinib on height and height velocity in patients with JIA.
• The analysis included 225 patients aged 2 years to less than 18 years with JIA (median age, 13.0 years; 75.1% girls), primarily with polyarticular course JIA, who received continuous tofacitinib treatment across three studies in the JIA development program conducted in 22 countries.
• Patients received open-label tofacitinib 5 mg twice daily or an equivalent weight-based lower dose, with a median treatment duration of 3.6 years, and 72.4% of patients were treated for more than 2 years.
• Height velocities (cm/y) and height Z scores based on age- and sex-matched reference data from the World Health Organization (WHO, 2007) were calculated, with measurements recorded at baseline, month 1, and month 3 and then every 3 months throughout the study.
• Levels of biomarkers — insulin-like growth factor 1 (IGF-1), IGF-binding protein-3 (IGFBP-3), and osteocalcin — were measured in serum from patients with JIA who completed 18 weeks of open-label treatment with tofacitinib. Pubertal status was categorized on the basis of the baseline Tanner stage.

TAKEAWAY:

• Patients with JIA had a baseline height distribution similar to the general population, with a median height Z score of -0.13 (IQR, -1.0 to 0.52), although short stature (height Z score < -2.0) was observed in 8.4% of patients compared with 2.5% expected in a normally distributed reference population.
• During tofacitinib treatment, height velocities appeared greater than expected for patients aged 12 years or younger but were at the expected rate for patients older than 12 years when compared with WHO age-appropriate norms.
• In patients who were pubertal at baseline and had a baseline height Z score < -1.0, an increase in height Z score vs baseline was detected after 24 months of treatment with tofacitinib (P < .05). Height Z scores tended to increase during tofacitinib treatment for patients aged 6-12 years at a baseline, particularly those with a baseline height Z score < -1.
• Tofacitinib treatment for 18 weeks did not affect levels of IGF-1, IGFBP-3, and osteocalcin in the overall population, but in patients aged 6-12 years, IGF-1 levels increased from baseline to 18 weeks (P = .032).

IN PRACTICE:

“In this post hoc analysis, patients with JIA began with near-normal height Z-scores, and during long-term treatment (ie, ≥ 24 months) with tofacitinib, their growth appeared normal,” the authors of the study wrote.

SOURCE:

The study was led by Hermine I. Brunner, MD, Cincinnati Children’s Hospital Medical Center, Cincinnati. It was published online April 30, 2026, in Annals of the Rheumatic Diseases.

LIMITATIONS:

The analysis was post hoc in nature and included a relatively small number of patients. The protocols of the three studies used in this analysis suggested using a Harpenden stadiometer for measuring height, but this was not a requirement, which could have led to less accurate measurements. The effect of change in pubertal status on growth was not considered in the analysis.

DISCLOSURES:

Pfizer sponsored the study, which was jointly designed by Pfizer and the Paediatric Rheumatology International Trials Organisation/Pediatric Rheumatology Collaborative Study Group officers. Pfizer was responsible for the overall management of the study and the data analysis. Some authors disclosed receiving research grants, consulting fees, or other remuneration and/or being members of speakers bureaus or data safety and monitoring boards for various companies, including Pfizer. Four authors reported being employees and stockholders of Pfizer, with two other authors being employees and stockholders at the time of analysis; one other author reported being an employee and stockholder of Kymera Therapeutics.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.