Abstract
BACKGROUND: Axial spondyloarthritis including ankylosing spondylitis (AS) is characterized by chronic inflammation and new bone formation in the axial skeleton. On the other hand, bone loss, osteoporosis and an increased risk of vertebral fractures is known to frequently occur in AS. In the MEASURE 1 study, the clinically efficacious interleukin-17A inhibitor secukinumab was shown to have limited radiographic progression through 4 years in patients with active AS. Here we present a post hoc analysis to evaluate the effect of secukinumab on bone mineral density (BMD) and bone turnover biomarkers over 2 years in this study. METHODS: BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine, total hip, and femoral neck. Spinal radiographs performed at baseline and Week 104 were assessed by modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and analyzed in relation to BMD change, considering baseline syndesmophytes. Bone turnover biomarkers were assessed at baseline and at Weeks 52 or 104. RESULTS: Among 104 patients included in this analysis, 66% were male, with a mean (SD) age of 40.4 (12.3) years. In postmenopausal women and men ≥50 years of age (T-score), the proportion of patients having normal BMD at baseline and Week 104 were 54.5%/54.5% (lumbar spine), 31.6%/55.6% (total hip), and 42.1%/44.4% (femoral neck). Similarly, at baseline, the proportion of patients with osteopenia/osteoporosis was 31.8%/13.6% (lumbar spine), 57.9%/10.5% (total hip), 42.1%/15.8% (femoral neck), and 36.4%/9.1% (lumbar spine), 44.4%/0% (total hip) and 55.6%/0% (femoral neck) at Week 104, respectively. In premenopausal women and men < 50 years of age (Z-score), the proportion of patients having BMD below the expected range for age at baseline and Week 104 were 25.0%/21.2% (lumbar spine), 11.3%/17.8% (total hip), and 9.9%/8.9% (femoral neck). In relation to mSASSS change scores ≥2 over 2 years, the increase in lumbar spine BMD was not related to radiographic progression and syndesmophyte formation. No significant changes were observed in the bone turnover markers over time. CONCLUSION: The high proportion of AS patients with diminished BMD was confirmed in this study. An increase of BMD in the lumbar spine after 2 years of secukinumab treatment in patients with AS was found that was probably unrelated to radiographic progression. No relevant effects of secukinumab on bone turnover biomarkers were documented. TRIAL REGISTRATION: MEASURE 1 (post hoc analysis) Clinicaltrials.gov, NCT01358175 ; Registered, 23 May 2011.