Mease et al. showed that guselkumab provided significantly higher rates of clinical improvement and significant inhibition of structural damage progression versus PBO, with no new safety signals, at Week 24 in biologic-naïve participants with active and erosive PsA. Mease et al. report primary efficacy and safety results for the double-blind PBO-controlled phase (Weeks 0-24) of the 3-year APEX study.