Ivarmacitinib in patients with active ankylosing spondylitis: subgroup analysis based on key baseline features from a phase II/III trial.

OBJECTIVES

This study aimed to evaluate the efficacy of ivarmacitinib in patients with active ankylosing spondylitis (AS) according to baseline characteristics.

METHODS

Data were derived from a phase II/III trial (NCT04481139). Patients with active AS who received either ivarmacitinib 4 mg (n = 187) or placebo (n = 186) were included. Subgroup analyses were performed based on age, sex, body mass index (BMI), AS duration, history of biological or Janus kinase (JAK) inhibitor use, C-reactive protein (CRP) level, total back pain visual analogue scale (VAS) score, and night pain VAS score.

RESULTS

At week 12 (W12), Assessment of SpondyloArthritis international Society 20% improvement (ASAS20) response rates were significantly higher in the ivarmacitinib arm compared to the placebo arm across subgroups stratified by sex, BMI, AS duration, history of biological/JAK inhibitor use, total back pain VAS score, and night pain VAS score. ASAS5/6 response rates at W12 were higher in the ivarmacitinib arm across all subgroups. Greater improvements in Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores at W12 were observed in the ivarmacitinib arm across subgroups defined by age, sex, BMI, AS duration, total back pain VAS score, and night pain VAS score. The ivarmacitinib arm achieved greater improvements in Ankylosing Spondylitis Disease Activity Score (ASDAS) at W12 across all subgroups. Efficacy outcomes improved through W24 across all subgroups with continuous ivarmacitinib treatment and after switching from placebo at W12.

CONCLUSION

Ivarmacitinib 4 mg demonstrated consistent efficacy in patients with active AS across diverse demographic and clinical subgroups. Key Points • Ivarmacitinib improved treatment response rates vs. placebo at W12 across multiple subgroups. • Efficacy benefits were sustained through 24 weeks after treatment with ivarmacitinib. • Efficacy improvements were observed after switching from placebo to ivarmacitinib.