Background/Purpose: Low bone mass is common in ankylosing spondylitis (AS) and patients (pts) with AS have an increased risk of bone fracture.^1-3 Treatment of AS pts with TNF inhibitors has resulted in bone mineral density (BMD) increases;^4,5 however, this has not been studied for IL-17A inhibitors yet. This is a post hoc analysis of the pivotal MEASURE 1 study⁶ with secukinumab 150 mg (approved dose for AS), in which changes in BMD and bone turnover biomarkers from baseline were assessed over 2 years.

Methods: A total of 104 pts originally randomized to the secukinumab 150 mg group with baseline BMD and at least one post-baseline lumbar spine BMD value at Week 52 or 104 were included in the analysis. BMD was assessed by dual-energy X-ray absorptiometry of the lumbar spine, total hip, and femoral neck at baseline, with the change from baseline in group mean calculated for the 150 mg group at Weeks 52 and 104. Additionally, to account for the variability in baseline BMD, the mean of individual percent changes in BMD at the lumbar spine, total hip, and femoral neck at Weeks 52 and 104 was also calculated. Bone turnover biomarkers (osteocalcin, procollagen type 1 N-terminal propeptide, procollagen-1 carboxy-terminal peptide, bone specific alkaline phosphatase, osteoprotegerin, sclerostin, and type I collagen C-telopeptides) were assessed at baseline, Weeks 52 and 104. Descriptive statistics were used to examine changes over time.

Results: At baseline, 66% were male pts and 34% female, with a mean age of 40.3 ± 12.3 years. Change from baseline in mean values for the 150 mg group at Weeks 52 and 104 for BMD (lumbar spine, total hip, and femoral neck) and bone turnover biomarkers are shown in the Table. The mean of individual BMD percent changes at Week 52 were 2.6% for lumbar spine, 0.9% for total hip, and 0.8% for femoral neck. Corresponding changes at Week 104 were 4.7% for lumbar spine, 0.5% for total hip, and 0.2% for femoral neck.

Conclusion: BMD increased over 2 years in AS patients treated with secukinumab 150 mg, with more pronounced increases observed in the lumbar spine. No consistent pattern was observed in the changes in bone turnover biomarkers through 2 years of treatment, although levels of the bone resorption biomarker Type I collagen C-telopeptides remained stable. References: 1. Davey-Ranasinghe N, Deodhar A. Curr Opin Rheumatol. 2013;25:509-16; 2. Malochet-Guinamand S, et al. BMC Musculoskelet Disord. 2017;18:357 ; 3. Ulu MA, et al. Chin Med J (Engl). 2014;127:2740-7; 4. van der Weijden MA, et al. J Rheumatol. 2016;43:758-64; 5. Li H, et al. J Rheumatol. 2015;42:1413-7; 6. Baeten D, et al. N Engl J Med. 2015;373:2534‒48.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/bone-mineral-density-and-serum-biomarkers-of-bone-turnover-in-ankylosing-spondylitis-patients-treated-with-secukinumab-2-year-data-from-the-pivotal-phase-3-study/