EULAR—Initial 24-week data from a study of patients with psoriatic arthritis (PsA) show that treatment with guselkumab improved symptoms and resulted in a higher ACR20 response than placebo in patients who could not tolerate, or did not respond to, treatment with a tumor necrosis factor inhibitor (TNFi).1
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These findings, presented by Laura C. Coates, MBChB, MRCP, PhD, a researcher and clinician at the University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, England, during EULAR’s 2021 virtual European Congress of Rheumatology, June 2–5, were the findings of the first part of the COSMOS trial (NCT03796858).2 This phase 3b clinical trial included two parts: 1) a 24-week, double-blind, placebo-controlled period to analyze the efficacy and safety of guselkumab compared with placebo; and 2) a 32-week, active-treatment and safety follow-up for additional analysis of guselkumab’s efficacy and safety. The study’s total duration was 56 weeks.
Guselkumab is a human monoclonal antibody that specifically binds to the p19 subunit of interleukin (IL) 23, inhibiting IL-23, the cytokine-induced release of pro-inflammatory cytokines and chemokines to improve psoriasis and PsA.3,4
Patients with active PsA (n=285), who had demonstrated a lack of benefit or were intolerant to one or two TNFi’s, were randomized in a 2:1 ratio to receive either 100 mg of subcutaneous guselkumab (n=189) or placebo (n=96) at weeks 0 and 4, and then every eight weeks through week 44. (Note: In this study, active PsA was defined as having at least three swollen and tender joints.)
Patients who were treated with placebo could cross over into the guselkumab-treatment group at week 24. Additionally at week 16, patients in the placebo group who experienced a less than a 5% improvement in both tender and swollen joint counts met the study’s early escape criteria and could switch to the guselkumab-treatment group.
The primary efficacy end point at week 24 was an ACR 20 response, which includes:
- An improvement of 20% in the number of tender and swollen joints; and
- A 20% improvement in three of the following five criteria:
- Patient global assessment of disease activity;
- Physician global assessment of disease activity;
- Patient assessment of pain using a visual analog scale;
- Patient’s assessment of physical function; and
- C-reactive protein.
Patients were considered non-responders if the ACR20 data was missing at week 24 or if they met the study’s early escape criteria at week 16. Additionally, a subgroup analysis was completed to assess consistency of the primary treatment effect based on demographics, disease characteristics and medication use at baseline. Adverse events were evaluated by treatment type.
Patients had similar baseline demographics. However, more women in the study received guselkumab than placebo (54% vs. 46%). At baseline, patients who received guselkumab had more severe joint symptoms, such as pain and more swollen/tender joints, as well as higher HAQ-DI and Physician Global Disease scores, compared with patients in the placebo group.