Phase IIIb APEX trial: Skin and nail outcomes with guselkumab in PsA

Results from 24 weeks of the randomized, double-blind, placebo-controlled, phase IIIb APEX (NCT04882098) trial, evaluating guselkumab in patients with psoriatic skin and nail disease and active psoriatic arthritis (PsA), were presented by Joseph F. Merola at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress, June 3–6, 2026, London, UK. Patients were assigned to receive either placebo (n = 376), guselkumab every 4 weeks (Q4W; n = 273), or guselkumab every 8 weeks (Q8W; n = 371). Skin disease endpoints included 100% improvement from baseline in Psoriasis Activity and Severity Index (PASI100) and Investigator’s Global Assessment score of 0 (IGA 0) responses. Nail disease endpoints included modified Nail Psoriasis Severity Index (mNAPSI) response and change from baseline, and Physician’s Global Assessment of Fingernail Psoriasis (PGA-F) response.

Key data: At Week 24, a greater proportion of patients receiving guselkumab Q4W and Q8W vs placebo achieved PASI100 (37.6% and 39.5% vs 11.6%; both p < 0.001) and IGA 0 (50.9% and 52.4% vs 14.6%; both p < 0.001) responses. Similarly, mNAPSI100 response rates were greater with guselkumab Q4W and Q8W vs placebo (34.1% and 32.7% vs 22.9%; both p < 0.05), with mean percentage changes in mNAPSI from baseline of −43.0%, −35.8%, and 16.1%, respectively. The PGA-F response rates were also higher with guselkumab Q4W and Q8W vs placebo (52.2% and 43.8% vs 23.4%; both p < 0.001).

Key learning: At Week 24, both guselkumab Q4W and Q8W significantly improved complete skin clearance and nail psoriasis outcomes compared with placebo in patients with PsA. Longer-term analyses from the APEX trial are ongoing.