Early Improvements with Guselkumab Associate with Sustained Control of Psoriatic Arthritis: Post hoc Analyses of Two Phase 3 Trials

Introduction: Patterns of treatment response can inform clinical decision-making. This study assessed the course and impact of achieving minimal clinically important improvement (MCII) in clinical measures and patient-reported outcomes (PROs) with guselkumab in patients with active psoriatic arthritis (PsA). Methods: Post hoc analyses evaluated 1120 patients with PsA receiving guselkumab every 4 or 8 weeks (Q4W/Q8W) or placebo from DISCOVER-1 (31% tumor necrosis factor inhibitor-experienced) and DISCOVER-2 (biologic-naïve). Achievement of MCII in clinical Disease Activity Index for PsA (cDAPSA), patient global assessment (PtGA) of arthritis, PtGA of psoriasis, patient-reported pain, Functional Assessment of Chronic Illness Therapy-Fatigue, Health Assessment Questionnaire-Disability Index, 36-item Short-Form Health Survey Physical Component Summary score, PtGA Arthritis + Psoriasis, and PsA Disease Activity Score (PASDAS) was compared between the guselkumab and placebo groups using Cox regression. Logistic regression adjusting for baseline factors evaluated associations between early (W4/W8) MCII achievement and stringent response (≥%50/%70 improvement in American College of Rheumatology response criteria, cDAPSA low disease activity [LDA], PASDAS LDA, and minimal disease activity) at W24/W52 among guselkumab-randomized patients. Results: Among patients with highly active PsA (baseline cDAPSA = 44.1–45.0, PASDAS = 6.4–6.5), times to MCII were significantly faster for guselkumab vs. placebo (hazard ratios 1.3–2.5; P < 0.05). Across measures, at first timepoint assessed, MCII rates were significantly higher with guselkumab (Q4W/Q8W 28–68%/29–65%) vs. placebo (19–47%; both P < 0.05). Early (W4/W8) MCII with guselkumab associated with higher odds of achieving stringent responses at W24/W52 (odds ratios 1.4–17.2/1.4–5.4). Conclusions: In a mixed PsA population, significant proportions of patients treated with guselkumab achieved early (W4/W8) MCII across clinical and PRO measures, which associated with a higher likelihood of attaining clinically relevant improvements and low levels of disease activity at W24/W52. Trial registration: DISCOVER-1 (NCT03162796). DISCOVER-2 (NCT03158285).