Efficacy and safety of adalimumab in Japanese patients with psoriatic arthritis and inadequate response to non-steroidal anti-inflammatory drugs (NSAIDs): A prospective, observational study.

To evaluate the efficacy and safety of adalimumab in psoriatic arthritis (PsA) patients in Japan. In this open-label, single-arm study conducted at six sites from October 2014 to June 2016 (UMIN000016543), PsA patients (≥20 years old) with inadequate response to nonsteroidal anti-inflammatory drugs received adalimumab subcutaneously (80 mg initially, then 40 mg every other week; 24 weeks total). Primary endpoint was American College of Rheumatology 20% improvement (ACR20) response rate at week 12. Of 42 enrolled patients, 37 were treated (mean (SD) age, 56.2 (13.0) years; male, 27 (73.0%)). ACR20, ACR50, and ACR70 response rates were 40.5%, 24.3%, and 16.2% at week 12 and increased to 45.9%, 37.8%, and 21.6% at week 24, respectively. Psoriasis Area and Severity Index (PASI) 50 response rates were unchanged at weeks 12 and 24 (73%), but PASI75 and PASI90 increased from 40.5% and 21.6% to 59.5% and 40.5%, respectively. Other indices such as Physician's Global Assessment score, C-reactive protein-based disease activity score in 28 joints, Bath Ankylosing Spondylitis Disease Activity Index, and serum biomarker levels were significantly improved. No unexpected adverse events were reported. Similar to the global population, adalimumab was efficacious and well tolerated in Japanese treatment-experienced PsA patients.