Guselkumab Significantly Reduces Disease Activity in TNFi-IR Psoriatic Arthritis

Guselkumab (GUS) treatment showed significant benefits for patients with psoriatic arthritis (PsA) who had inadequate response to at least 1 tumor necrosis factor inhibitors (TNFi-IR), according to the study “Guselkumab Efficacy in Psoriatic Arthritis Assessed by Multi-domain Composite Indices: Data from the Phase 3b COSMOS Trial in a TNFi-IR Population,” presented at the American College of Rheumatology Convergence 2022. Low levels of disease activity were achieved and increased throughout the study.

The Study

The Phase 3b COSMOS study (NCT03796858) assessed the safety and efficacy of GUS in TNFi-IR PsA. Patients in the GUS group (n = 189) were given 100 mg every 8 weeks (Q8W) through 52 weeks and were evaluated by via 6 multi-domain composite indices validated in PsA: the PsA Disease Activity Score (PASDAS), Disease Activity Index for PsA (DAPSA), GRAppa Composite scorE (GRACE), a modified Composite Psoriatic Disease Activity Index (mCPDAI, which excluded Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]), PsA Response Criteria (PsARC), and Minimal Disease Activity (MDA). Data was evaluated at baseline, week 24, and week 48.

Of the 285 patients enrolled in the study, the mean age was 49 years, and the mean disease duration was 8.4 years. Those originally placed in the placebo group (n = 96) started GUS at either week 16 (n = 45) or week 24 (n = 51) (PBOàGUS).

The Findings

Most patients (88% in the GUS cohort and 86% in the PBOàGUS group) completed the study through week 44. Patients had similar disease activity at baseline regarding PASDAS, DAPSA, GRACE, and mCPDAI. Those receiving GUS had robust improvements in mean scores from baseline to week 48 (45-62%). Further, patients in the PBOàGUS reported rapid improvements in index scores that were comparable to patients randomized to GUS at baseline.

Evaluations focusing on low disease activity (LDA) and joints (DAPSA and PsARC) reported the highest response rates (ranging from 50-80%). However, LDA according to GRACE and PASDAS, which included skin and musculoskeletal assessments, were attained less frequently (ranging from 38-44%). The PsARC showed that 50% of GUS-treated patients responded to treatment as early as week 8 and response rates did not plateau by week 48. At the 48-week mark, 33% of those in the GUS group and 30% of patients in the PBOàGUS cohort achieved MDA.

“These findings support the role of GUS as an effective treatment option for the diverse domains of PsA,” investigators concluded.