Background/Purpose: Patients (pts) with PsA can develop axial inflammation in the SI joints (SIJs) and/or spine. Although validated classification criteria for axial spondyloarthritis exist, established criteria for classifying axial PsA are lacking. STAR (NCT04929210), a Phase 4, multicenter, randomized, controlled trial of biologic-naïve PsA pts with current neck/back/hip (spinal) pain and MRI-confirmed axial inflammation, is prospectively evaluating the efficacy of guselkumab (GUS), IL-23p19-subunit inhibitor, on axial symptoms and objective measures (MRI) of axial inflammation.¹ This exploratory analysis of available screening MRI data from STAR compared clinical-characteristics between pts meeting vs not meeting STAR MRI eligibility criteria.

Methods: STAR is designed to randomize (1:1:1) 405 pts to GUS every 4 weeks (Q4W); GUS at W0, W4, then Q8W; or placebo→GUS Q8W at W24. Eligibility criteria include active PsA (≥3 swollen and ≥3 tender joints, CRP ≥0.3 mg/dL) despite non-biologic DMARDs, apremilast, and/or NSAIDs. Eligible pts are naïve to biologics/Janus kinase inhibitors and have BASDI ≥4, BASDI spinal pain score ≥4, and screening MRI-confirmed axial involvement (positive spine and/or SIJ MRI defined by blinded, centrally-read Spondyloarthritis Research Consortium of Canada score ≥3). SI Joint/Spine MRI reading involves 2 central readers and an adjudicator; agreement by 2 readers confirms positive (+)/negative (–) MRI result. Pt clinical characteristics and medical history at screening were compared between MRI+ and MRI– cohorts to determine those associated with MRI-detected inflammation of SIJ and/or Spine (Figure).

Results: Of 487 pts screened to date, those with non-missing MRI results included 459 for SIJ (34% MRI+), 461 for Spine (30% MRI+), and 433 for both SIJ and Spine (15% SIJ+/Spine+, 26% SIJ+/Spine– or SIJ–/Spine+, 59% SIJ–/Spine–). Male gender and serum CRP levels were significantly higher in both SIJ+ vs SIJ– and Spine+ vs Spine– cohorts. SIJ+ cohort pts were younger (mean age: 44.7 vs 47.4 yrs) with higher spinal pain score (mean: 7.7 vs 7.3) and fewer tender joints (mean: 12.6 vs 15.5) vs SIJ– cohort pts (all nominal p< 0.05). Consistent numerical differences (not statistically significant) were seen in spinal back pain score and tender joint counts between the Spine+ and Spine– cohorts (Table). The SIJ+ cohort had numerically higher proportions of pts with a history of inflammatory back pain, nail psoriasis, and scalp psoriasis vs the SIJ– cohort. Pts with palmoplantar psoriasis history were less likely to exhibit MRI-detected inflammation in the SIJ or Spine (Figure). Differences between the SIJ+/Spine+ (N=65) and SIJ–/Spine– (N=257) cohorts were generally aligned with those of the site-specific cohorts (data not shown).

Conclusion: Preliminary findings from an established STAR PsA cohort: 1) are consistent with the recognized positive association between serum CRP levels and axial involvement in PsA and 2) provide initial evidence that several clinical characteristics may associate with presence/absence of MRI-detected axial inflammation. STAR is actively enrolling.

1. Gladman. Trials. doi.org/10.1186/s13063-022-06589-y

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/associations-between-clinical-characteristics-and-screening-mri-findings-exploratory-analysis-of-the-ongoing-phase-4-multicenter-randomized-controlled-star-study-of-biologic-naive-patients-with-ps/