medwireNews: It may be possible to identify patients with axial spondyloarthritis (AxSpA) who are unlikely to respond to tumor necrosis factor (TNF) inhibitor treatment using their baseline factors, researchers report.
“Identifying the characteristics of AxSpA patients and predicting the response prior to starting TNF [inhibitor treatment] is an important issue, especially in view of the high costs and potential adverse effects of biologics,” say Nigil Haroon (Toronto Western Hospital, Ontario, Canada) and study co-authors.
At present “there is no established biomarker, imaging modality or clinical parameter that can reliably predict TNF [inhibitor] failure,” they add.
In a retrospective database analysis, the team found that 155 of 249 AxSpA patients who were treated with TNF inhibitors stopped or switched their medication due to lack of efficacy. Of these patients, 40% were categorized as having no initial response to treatment (primary lack of response; PLR), while 60% had secondary lack of response (SLR), defined as loss of effectiveness following an initial good therapeutic response.
The mean duration of biologic treatment was 4.6 months and 33.9 months for patients in the PLR and SLR groups, respectively, and 59.1 months for those who responded to treatment. Infliximab was the most commonly prescribed TNF inhibitor, taken by 33.3% of patients, followed by etanercept (25.3%), adalimumab (28.1%), and golimumab (13.3%).
When patients in the PLR group were compared with those in the SLR and responder groups – categorized together as the “any response” group – patients with primary failure were significantly older (40.8 vs 36.1 years), had significantly higher baseline Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores (6.8 vs 6.2 points), and had lower rates of human leukocyte antigen (HLA)-B27 surface antigen positivity (64.5 vs 78.1%).
And in multiple regression analyses, older age, HLA-B27 negativity, higher baseline BASDAI score, and treatment with soluble TNF inhibitors were identified as significant predictors of PLR after accounting for factors including sex, smoking, and type of treatment, with odds ratios of 1.04, 2.00, 1.26, and 2.38, respectively.
These “distinct features” may characterize patients with initial failure to TNF inhibitor treatment, say the researchers in Arthritis Care & Research.
They acknowledge, however, that the study was limited by its small sample size and lack of information on anti-drug antibodies.
And the team concludes that “[f]urther studies are needed to confirm our results,” including an investigation into clinical outcomes based on treatment failure type.
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