Impact of guselkumab, an interleukin-23 p19 subunit inhibitor, on enthesitis and dactylitis in patients with moderate to severe psoriatic arthritis: results from a randomised, placebo-controlled, phase II study

Objective To evaluate the effect of guselkumab on enthesitis and dactylitis in a phase II trial of patients with active psoriatic arthritis (PsA). Methods This was a phase II, randomised, placebo-controlled, double-blind trial of adults with active PsA (≥3 swollen and ≥3 tender joints and C reactive protein ≥0.3 mg/dL) despite conventional synthetic disease-modifying anti-rheumatic drug, non-steroidal anti-inflammatory drug, and/or oral corticosteroid therapy. Patients were randomised to subcutaneous injections of guselkumab 100 mg or placebo at weeks 0, 4 and every 8 weeks, with placebo crossover to guselkumab at week 24. Dactylitis was scored on a scale of 0–3 on each digit; enthesitis was assessed using the Leeds Enthesitis Index (0–6). Other assessments included American College of Rheumatology (ACR) and Psoriasis Area and Severity Index responses. Results Of 149 randomised patients, 107 patients had enthesitis (mean score=2.7) and 81 patients had dactylitis (mean dactylitis score=5.7) at baseline. Mean improvements in enthesitis and dactylitis at week 24 were greater in the guselkumab group versus placebo and sustained through week 56. Similar results were observed for the proportions of patients with resolution of enthesitis and dactylitis. At week 56, mean improvements in enthesitis and dactylitis among patients who switched from placebo to guselkumab treatment were similar to those in the guselkumab group. In the guselkumab group, ACR20 responders had greater improvements in enthesitis and dactylitis versus non-responders (week 24). Conclusions At week 24, the guselkumab group had greater mean improvements in enthesitis and dactylitis and greater proportions of patients with resolution of enthesitis and dactylitis versus placebo. ACR20 response was associated with improvements in enthesitis and dactylitis