What do biomarkers tell us about the pathogenesis of ankylosing spondylitis?

Biomarkers may provide information that promotes understanding of prognosis, disease activity, and pathogenesis in ankylosing spondylitis. Biomarkers reflecting disease activity (metallo-proteinase-3) and inflammatory lesions on magnetic resonance imaging predict new bone formation and are ameliorated by anti-tumor necrosis factor therapy, yet this treatment may not prevent new bone formation. Moreover, elevated levels of biomarkers reflecting tissue repair (bone-specific alkaline phosphatase) post-treatment together with magnetic resonance imaging indicates such treatment may even promote repair through new bone formation. Tumor necrosis factor regulation of Dickkopf-1 may constitute a molecular brake that controls osteoblastogenesis through wingless and bone morphogenetic proteins in an established inflammatory lesion in ankylosing spondylitis

Progress in spondylarthritis. Spondyloarthritis: lessons from imaging

The advent of magnetic resonance imaging (MRI) and advanced sonographic techniques has led to a resurgence of interest in the role of imaging in the evaluation and management of spondyloarthritis. Radiography remains the cornerstone of diagnosis although MRI is more sensitive in early stages of the disease. Inflammatory changes in the sacroiliac joints and spine can now be reliably quantified and can also predict the subsequent development of radiographic changes in the corresponding locations. MRI-based scoring systems for inflammation are highly responsive, facilitating proof-of-concept studies of new therapies for spondyloarthritis. Assessment of chronic changes is much less reliable using MRI, while assessment using radiography lacks sensitivity to change. Assessment of disease modification therefore remains a principle challenge in the development of new therapies for ankylosing spondylitis. Ultrasound may be the preferred approach to the assessment of peripheral inflammation, especially enthesitis. Scintigraphy and computed tomography offer few advantages over MRI

Biomarkers for Diagnosis of Axial Spondyloarthritis, Disease Activity, Prognosis, and Prediction of Response to Therapy

There exists a major unmet need for biomarkers that can identify axial spondyloarthritis (axSpA) early after disease onset because of the availability of highly effective therapies. Several recent reports have examined the autoantibody response in patients with axSpA through the use of protein microarrays and protein-protein interactions although diagnostic performance of biomarkers identified to date has been inadequate. An example of such a biomarker is protein phosphatase magnesium-dependent 1A. Antibodies to the human leukocyte antigen class II-associated invariant chain peptide (anti-CD74) are candidate diagnostic biomarkers but sensitivity declines with increasing duration of disease. Metabolomic studies have employed nuclear magnetic resonance (NMR) spectrometry to identify disease-specific metabolites related to fat metabolism and intestinal microbial metabolism. A second major unmet need exists for biomarkers of disease activity that have superiority over standard C-reactive protein assessment and reflect MRI inflammation in the axial spine. Several biomarkers reflecting inflammation (calprotectin), angiogenesis (vasoactive endothelial growth factor), and connective tissue turnover (C2M, C3M, and citrullinated metalloproteinase degraded fragment of vimentin) have recently been shown to reflect disease activity when compared with clinical outcomes but comparisons with MRI inflammation are very limited. With increasing availability of highly effective but costly therapies, a third unmet need is biomarkers that can predict response to therapies with different mechanisms of action and are superior to C-reactive protein. Calprotectin is currently the only candidate. Although there are as yet no proven therapies for preventing progression of disease there is an unmet need for biomarkers of prognosis that are more responsive than radiography. Aside from CRP no consistent candidates have emerged. Future studies will need to be prospective, include consecutive patients presenting with undiagnosed back pain, and use more reliable and objective endpoints such as MRI inflammation. Moreover, it has become evident that targeted biomarker studies have not been successful in identifying clinically useful biomarkers and technologies that can simultaneously assess “multiomic” markers will need to be analyzed for future advances. These include more sophisticated metabolomic profiling and universal metabolome-standard (UMS) methodology, next generation RNA sequencing, and affinity-based quantitative proteomics based on the use of nucleic acid binders such as the aptamer-based SOMAscan assay

Tumor necrosis factor inhibitor therapy but not standard therapy is associated with resolution of erosion in the sacroiliac joints of patients with axial spondyloarthritis

INTRODUCTION: Radiography is an unreliable and insensitive tool for the assessment of structural lesions in the sacroiliac joints (SIJ). Magnetic resonance imaging (MRI) detects a wider spectrum of structural lesions but has undergone minimal validation in prospective studies. The Spondyloarthritis Research Consortium of Canada (SPARCC) MRI Sacroiliac Joint (SIJ) Structural Score (SSS) assesses a spectrum of structural lesions (erosion, fat metaplasia, backfill, ankylosis) and its potential to discriminate between therapies requires evaluation. METHODS: The SSS score assesses five consecutive coronal slices through the cartilaginous portion of the joint on T1-weighted sequences starting from the transitional slice between cartilaginous and ligamentous portions of the joint. Lesions are scored dichotomously (present/absent) in SIJ quadrants (fat metaplasia, erosion) or halves (backfill, ankylosis). Two readers independently scored 147 pairs (baseline, 2 years) of scans from a prospective cohort of patients with SpA who received either standard (n = 69) or tumor necrosis factor alpha (TNFα) inhibitor (n = 78) therapy. Smallest detectable change (SDC) was calculated using analysis of variance (ANOVA), discrimination was assessed using Guyatt’s effect size, and treatment group differences were assessed using t-tests and the Mann–Whitney test. We identified baseline demographic and structural damage variables associated with change in SSS score by univariate analysis and analyzed the effect of treatment by multivariate stepwise regression adjusted for severity of baseline structural damage and demographic variables. RESULTS: A significant increase in mean SSS score for fat metaplasia (P = 0.017) and decrease in mean SSS score for erosion (P = 0.017) was noted in anti-TNFα treated patients compared to those on standard therapy. Effect size for this change in SSS fat metaplasia and erosion score was moderate (0.5 and 0.6, respectively). Treatment and baseline SSS score for erosion were independently associated with change in SSS erosion score (β = 1.75, P = 0.003 and β = 0.40, P < 0.0001, respectively). Change in ASDAS (β = −0.46, P = 0.006), SPARCC MRI SIJ inflammation (β = −0.077, P = 0.019), and baseline SSS score for fat metaplasia (β = 0.085, P = 0.034) were independently associated with new fat metaplasia. CONCLUSION: The SPARCC SSS method for assessment of structural lesions has discriminative capacity in demonstrating significantly greater reduction in erosion and new fat metaplasia in patients receiving anti-TNFα therapy

Clinical and MRI responses to etanercept in early non-radiographic axial spondyloarthritis : 48-week results from the EMBARK study

Objective: To evaluate the efficacy and safety of etanercept (ETN) after 48 weeks in patients with early active non-radiographic axial spondyloarthritis (nr-axSpA). Methods: Patients meeting Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA, but not modified New York radiographic criteria, received double-blind ETN 50 mg/week or placebo (PBO) for 12 weeks, then open-label ETN (ETN/ETN or PBO/ETN). Clinical, health, productivity, MRI and safety outcomes were assessed and the 48-week data are presented here. Results: 208/225 patients (92%) entered the open-label phase at week 12 (ETN, n=102; PBO, n=106). The percentage of patients achieving ASAS40 increased from 33% to 52% between weeks 12 and 48 for ETN/ETN and from 15% to 53% for PBO/ETN (within-group p value <0.001 for both). For ETN/ETN and PBO/ETN, the EuroQol 5 Dimensions utility score improved by 0.14 and 0.08, respectively, between baseline and week 12 and by 0.23 and 0.22 between baseline and week 48. Between weeks 12 and 48, MRI Spondyloarthritis Research Consortium of Canada sacroiliac joint (SIJ) scores decreased by -1.1 for ETN/ETN and by -3.0 for PBO/ETN, p<0.001 for both. Decreases in MRI SIJ inflammation and C-reactive protein correlated with several clinical outcomes at weeks 12 and 48. Conclusions: Patients with early active nr-axSpA demonstrated improvement from week 12 in clinical, health, productivity and MRI outcomes that was sustained to 48 weeks

Matching-adjusted indirect comparison of the 52-week efficacy of bimekizumab versus secukinumab and ixekizumab for the treatment of radiographic axial spondyloarthritis

Introduction: A previous network meta-analysis established 16-week relative efficacy with bimekizumab, an inhibitor of interleukin (IL)-17F in addition to IL-17A, versus other treatments for patients with radiographic axial spondyloarthritis (r-axSpA; i.e., ankylosing spondylitis), including the IL-17A inhibitors secukinumab and ixekizumab. This matching-adjusted indirect comparison (MAIC) assessed 52-week relative efficacy of bimekizumab versus secukinumab and ixekizumab. Methods: Individual patient data from BE MOBILE 2 (bimekizumab 160 mg; N = 220) were matched to pooled summary data from MEASURE 1/2/3/4 (secukinumab 150 mg), MEASURE 3 (secukinumab 300 mg; escalated dose for inadequate responders), COAST-V (ixekizumab) and COAST-V/-W (ixekizumab). BE MOBILE 2 patients were reweighted using propensity score weights based on age, sex, ethnicity, tumor necrosis factor inhibitor (TNFi) exposure, weight, baseline ASDAS and BASFI (secukinumab) and baseline BASDAI (ixekizumab), and 52-week efficacy outcomes from the trial recalculated. Odds ratios (OR) or mean difference for unanchored comparisons are reported with 95% confidence intervals (CI). Results: At week 52, MAIC demonstrated that patients may have higher likelihood of improvement in key efficacy outcomes with bimekizumab versus secukinumab 150 mg (e.g., ASAS40: [OR (95% CI): 1.48 (1.05, 2.10); p = 0.026]; effective sample size [ESS] = 177). Differences in 52-week efficacy outcomes between bimekizumab and secukinumab 300 mg dose escalation were non-significant (ESS = 120). Bimekizumab versus ixekizumab 80 mg comparisons (COAST-V only; ESS = 84) also suggested that differences were non-significant for most key efficacy outcomes. Other ixekizumab comparisons (COAST-V/-W; ESS = 45) suggested bimekizumab may have higher comparative efficacy for many of the same efficacy outcomes, however ixekizumab analyses were limited by poor population overlap, likely due to the greater proportion of patients with previous TNFi exposure. Conclusions: Patients treated with bimekizumab may have a higher likelihood of achieving improved longer-term efficacy versus secukinumab 150 mg, suggesting bimekizumab may be a favorable therapeutic option for r-axSpA. Differences in efficacy outcomes with bimekizumab versus ixekizumab 80 mg were mostly non-significant, depending on the populations considered