Multi-domain effectiveness of guselkumab evaluated via composite indices through 1 year in patients with PsA and inadequate response to TNFi: post hoc analysis of COSMOS

Objective: Evaluate guselkumab efficacy, an anti-interleukin-23p19-subunit antibody, in patients with active psoriatic arthritis (PsA) and inadequate response to 1–2 tumour necrosis factor inhibitors (TNFi-IR), utilizing composite indices assessing disease activity across disease domains. Methods: In the Phase IIIb COSMOS trial, 285 adults with TNFi-IR PsA were randomized (2:1) to receive guselkumab 100 mg or placebo at Week (W)0, W4, then every 8 weeks through W44. Patients receiving placebo crossed over to guselkumab at W24. In this post-hoc analysis, composite indices evaluated included the Disease Activity Index for Psoriatic Arthritis (DAPSA), Disease Activity Score 28 (DAS28), Psoriatic Arthritis Response Criteria (PsARC), Psoriatic Arthritis Disease Activity Score (PASDAS), GRAPPA Composite score (GRACE), modified Composite Psoriatic Disease Activity Index (mCPDAI), minimal disease activity (MDA) and very low disease activity (VLDA). Through W24, treatment failure rules were applied. Through W48, non-responder imputation was used for missing data. Results: Greater proportions of guselkumab- than placebo-randomized patients achieved composite index endpoints relating to low disease activity (LDA; 14.8–52.4% vs 3.1–28.1%) or remission (3.7–5.3% vs 0.0–2.1%) at W24. Among guselkumab-randomized patients, LDA rates increased to W48 (DAPSA, 44.4%; DAS28, 47.8%; PASDAS, 34.4%; GRACE, 33.3%; mCPDAI, 40.2%), and 27.0% and 64.0% achieved MDA and a PsARC response, respectively. In the placeboàguselkumab crossover group, W48 response rates were similar to the guselkumab-randomized group. Conclusion: Guselkumab treatment provided substantial benefits across multiple disease domains, with increasing proportions of patients achieving LDA/remission over 1 year, highlighting the effectiveness of guselkumab despite previous inadequate response to TNFi.