Efficacy of tofacitinib on enthesitis in patients with active psoriatic arthritis: analysis of pooled data from two phase 3 studies

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor for the treatment of psoriatic arthritis (PsA). This post hoc analysis assessed tofacitinib efficacy on enthesitis by baseline location and severity, and impact on disease activity and patient-reported outcomes (PROs), in patients with PsA. METHODS: Data were pooled from two phase 3 studies (NCT01877668/NCT01882439) in patients with PsA receiving tofacitinib 5 or 10 mg twice daily to month (M)6 or placebo to M3. Endpoints were: change from baseline in Leeds Enthesitis Index (LEI) or Spondyloarthritis Research Consortium of Canada Enthesitis Index (SPARCC); proportions of patients with enthesitis, relapsed enthesitis after resolution, de novo enthesitis, low disease activity (LDA) or remission (minimal disease activity/very low disease activity; Psoriatic Arthritis Disease Activity Score; Disease Activity Index for Psoriatic Arthritis, and Composite Psoriatic Disease Activity in Psoriatic Arthritis); and PROs (Functional Assessment of Chronic Illness Therapy-Fatigue [FACIT-F] total and arthritis pain Visual Analog Scale scores). Descriptive statistics were generated by visit and treatment. Change from baseline in PROs was evaluated by multivariate linear regression. RESULTS: Seven hundred ten patients from two studies were included: 479 had LEI > 0; 545 had SPARCC > 0; and 136 had LEI = 0 and SPARCC = 0 at baseline. At baseline, among patients with LEI > 0 or SPARCC > 0, mean LEI and SPARCC across treatments and enthesitis locations/severities ranged from 1.0–4.4 and 1.3–9.4, respectively. Across several baseline enthesitis locations/severities, changes from baseline in LEI and SPARCC up to M3 were greater with tofacitinib (-2.0–0.4 and -3.5–0.2) vs placebo (-‍0.9–‍0.4 and -1.5–1.1). Enthesitis at M6 was more common in patients with greater baseline enthesitis severity. At M6, ≤ 40% of patients with baseline LEI > 0 or SPARCC > 0 whose enthesitis had resolved by M1/M3 experienced a relapse, and < 14% of patients with baseline LEI = 0 and SPARCC = 0 had de novo enthesitis. LDA/remission rates generally increased with tofacitinib over time. Baseline LEI location was significantly associated with change from baseline in arthritis pain score, while baseline SPARCC severity was significantly associated with change from baseline in FACIT-F total and arthritis pain scores. CONCLUSION: Tofacitinib treatment resulted in improvements in enthesitis in patients with PsA, regardless of baseline location or severity. TRIAL REGISTRATION: NCT01877668;NCT01882439. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13075-023-03108-5.