Background/Purpose:

The treatment of spondyloarthritis (SpA) has improved dramatically since the introduction of TNF-blockade. However, this therapy is only approved and reimbursed for the treatment of ankylosing spondylitis (AS) and psoriatic arthritis (PsA), which are the best described and studied phenotypic subtypes of SpA. Approximately one third of the SpA population can not be classified as AS or PsA. Randomized clinical trials (RCTs) in non-radiographic axial SpA have recently been performed and showed good results, but for peripheral non-AS, non-PsA SpA patients RCTs are lacking. This study aimed to assess the efficacy and safety of adalimumab in patients with peripheral SpA not fulfilling the criteria for AS or PsA.

Methods:

Forty patients with active peripheral SpA fulfilling the ESSG or Amor criteria but not the criteria for AS or PsA were included in a randomized, double-blind, placebo-controlled clinical trial. Patients were treated 1:1 with adalimumab or placebo for 12 weeks, followed by an open label extension up to week 24. Safety and efficacy measurements were performed every 6 weeks, with as primary endpoint the patient’s global assessment of disease activity at week 12.

Results:

The baseline demographic and disease characteristics were similar across both treatment arms, except for HLA-B27 positivity which tended to be higher in the adalimumab group (55%) versus the placebo group (25%) (P=0.053), and the physician’s global assessment of disease activity which was somewhat higher in the placebo (57.0 ± 12.6 mm) versus the adalimumab treated patients (47.8 ± 11.8 mm) (P=0.022). At week 12 the patient’s and physician’s global assessment of disease activity, swollen joint count, BASDAI, ASDAS and ESR improved significantly in the adalimumab group compared with the baseline values and compared with placebo (Table 1). A similar improvement was seen upon adalimumab treatment from week 12 to 24 in the patients originally randomized to placebo, whereas the clinical response was maintained or even augmented at week 24 in the patients who received adalimumab from the beginning. ASDAS inactive disease and BASDAI50 responses were met in 42% of the adalimumab group versus 0-5% in the placebo group at week 12 (P=0.001 and P=0.008 respectively), and were further increased at week 24. Quality of life and disability scores also improved upon adalimumab treatment. Multiple regression analysis showed that features such as gender, HLA-B27 status and concomitant DMARD treatment did not act as confounders in this trial. The number of adverse events was not different between the adalimumab and placebo group.

Conclusion:

Adalimumab is effective and safe in SpA patients with active peripheral disease, also in those patients not fulfilling the AS or PsA criteria. Therefore, this treatment should be considered and made available for these patients when their peripheral SpA is refractory to conventional treatments.