Factors identified for predicting TNF inhibitor response in non-radiographic axSpA
medwireNews: Researchers have identified baseline predictors of clinical remission in patients with non-radiographic axial spondyloarthritis (axSpA) taking tumor necrosis factor (TNF) inhibitors.
The findings, from the ABILITY-3 study, show that the key predictors are younger age, positivity for human leukocyte antigen (HLA)-B27, inflammation of the sacroiliac (SI) joints on magnetic resonance imaging (MRI), better functional status, increased morning stiffness, and lower dose activity.
In all, 673 patients who met the Assessment of SpondyloArthritis International Society (ASAS) criteria for axSPA, but not the radiologic criterion of the modified New York criteria for AS, were treated with adalimumab 40 mg every 2 weeks for 12 weeks.
The patients had active disease, with elevated scores on the Ankylosing Spondylitis Disease Activity Score (ASDAS; ≥2.1 points) and the Bath Ankylosing Spondyloarthritis Disease Activity Index (BADSAI; ≥4 points), and an inadequate response, intolerance, or contraindication to at least two non-steroidal anti-inflammatory drugs. They also had MRI evidence of inflammation including bone marrow edema in SI joints or the spine and elevated high-sensitivity C-reactive protein (hs-CRP) levels.
At week 12, 35% of 600 patients were in clinical remission according to the inactive disease criteria of the ASDAS, and 22% of 603 based on the ASAS partial remission criteria.
The findings show that patients who achieved clinical remission, according to either measure, were significantly more likely than those who did not achieve remission to be younger at baseline (32 to 33 years vs 39 years), have a longer disease duration (5 to 6 years vs 8 years), and test positive for HLA-B27 (87 to 89% vs 70 to 72%). They were also more likely to have inflammation of the SI joints on MRI (77 to 78% vs 67 to 70%).
Additional significant predictors in the group meeting clinical remission according to ASDAS included increased morning stiffness (inflammation) and lower disease activity on the Bath Ankylosing Spondylitis Functional Index (BASFI).Lower disease activity on the Health Assessment Questionnaire for the Spondylarthropathies (HAQ-S) and elevated hs-CRP levels were significant predictors of remission for the patients meeting ASAS partial remission.
Presenting the findings at the Annual European Congress of Rheumatology (EULAR) 2017 in Madrid, Spain, Joachim Sieper, from Charité Universitätsmedizin in Berlin, Germany, explained that the discrepancy in hs-CRP levels as a predictor might be due to most of the patients having elevated levels at baseline and the fact that the ASDAS for partial remission does not include CRP levels whereas the ASAS does.
Sieper also highlighted the open-label design of the 12-week study as a potential limitation, but he noted that “this might represent daily clinical practice better than a placebo-controlled or blinded trial.”
He concluded that the predictors of clinical response to TNF inhibitor therapy identified in his study are similar to those for ankylosing spondyloarthritis remission, which makes it “even more important to identify patients early in the course of the disease and probably also to treat these patients earlier so that we can expect better outcome.”
By Lucy Piper
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