MRI sacroiliitis, HLA-B27 predict long-term response to certolizumab pegol in axial SpA
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In patients with non-radiographic axial spondyloarthritis, MRI sacroiliitis and HLA-B27 positivity, but not elevated C-reactive protein or responses at week 12, predict long-term certolizumab pegol response, according to data.
“Non-radiographic axial spondyloarthritis can be a challenging diagnosis in the absence of radiographic sacroiliitis and selecting patients for treatment with expensive therapeutics is even more challenging,” Walter P. Maksymowych, MD, of the University of Alberta, in Edmonton, Canada, told Healio Rheumatology.
According to Maksymowych and his fellow researchers, few predictive analyses exist for non-radiographic axial SpA, with available data limited to short-term treatment responses only.
“The identification of predictive clinical factors of long-term response in nr-axSpA may help to differentiate appropriate patients suitable for TNFi treatment, while providing confidence in the treatment choice from both a physician and patient perspective, particularly in the early disease phase,” Maksymowych and colleagues wrote in Arthritis Research & Therapy.
To determine whether any baseline characteristics or week 12 outcomes can predict clinical response after 1 year of certolizumab pegol (Cimzia, UCB) in non-radiographic axial SpA with elevated CRP and/or MRI sacroiliitis, Maksymowych and colleagues conducted a post hoc analysis of the phase 3 C-axSpAnd trial. In that trial, which included a 52-week, double-blind, placebo-controlled period, 317 participants were randomly assigned 1:1 to receive 200 mg of certolizumab pegol every 2 weeks or placebo.
For their own study, Maksymowych and colleagues used a multivariate stepwise logistic regression analysis to determine predictors of clinical response at week 12 — only in those treated with certolizumab pegol — and week 52. Response variables included Ankylosing Spondylitis Disease Activity Score major improvement (ASDAS-MI), Assessment of Spondyloarthritis International Society 40% response (ASAS40), Bath Ankylosing Spondylitis Disease Activity Index 50% response (BASDAI50), and ASDAS inactive disease (ASDAS-ID).
The researchers required P values of less than 0.05 for forward selection into the model and at least 0.1 for backward elimination. They used sensitivity analyses to account for participants with changes in non-biologic background treatment.
According to the researchers, younger age and male sex predicted week 12 response across all efficacy outcomes in participants who received certolizumab pegol. For week 52 response, consistent predictors — based on ASDAS-MI, ASAS40 and BASDAI50 — included HLA-B27 positivity and MRI sacroiliitis at baseline. MRI positivity also predicted achieving ASDAS-ID at week 52. Sensitivity analyses were generally consistent with the primary analysis, the researchers wrote. There were no meaningful predictors of week 52 response among participants who received placebo.
“We demonstrated in this 52-week, placebo-controlled RCT that the presence of inflammation on MRI of the sacroiliac joints combined with HLA-B27 positivity in the same patient is a major predictor of treatment response to a biologic, certolizumab,” Maksymowych said.
“This work illustrates the importance of MRI evaluation of the sacroiliac joints, not only for diagnostic evaluation for this condition, but also for appropriate selection of patients for treatment,” he added. “It is therefore incumbent on physicians to ensure they understand principles of MRI evaluation of the sacroiliac joints and the significance of the different types of lesions that can be found in this location.”
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