Effects of secukinumab on skeletal microarchitecture and vertebral fractures in patients with axial spondyloarthritis using HR-pQCT.

Participants with active AxSpA beginning secukinumab with moderate disease activity had improvements in symptoms, but no substantial change in BMD and microarchitecture. Larger, longer-term controlled studies are needed to assess the impact of IL-17 blockade on skeletal health.

Background: Axial Spondyloarthritis (AxSpA) is linked to poor skeletal health, but whether IL-17 blockade, effective for symptom improvement, improves skeletal health is unknown. We investigated the impact of secukinumab on skeletal features.

Methods: We prospectively enrolled AxSpA patients beginning therapy with secukinumab and followed them for 24 months. Clinical assessments, serum bone turnover markers, and cervical and lumbar spine radiographs were obtained. Areal BMD (aBMD) and trabecular bone score (TBS) measured by dual energy x-ray absorptiometry (DXA, spine, hip, forearm), volumetric BMD (vBMD), and microarchitecture measured by high-resolution peripheral quantitative computed tomography (HR-pQCT, Xtreme CT2, at the tibia and radius) were performed annually. DXA and HR-pQCT assessments were compared to reference cohorts of sex- and age-matched individuals. Changes were assessed through Wilcoxon and paired t-tests.

Results: Thirty AxSpA participants were enrolled, 50% female (13% postmenopausal) and 47% HLA-B27 positive. Mean symptom duration was 12 years, with moderate activity (BASDAI mean 5 [SD = 2]). Baseline DXA and HR-pQCT Z-scores were within 1 standard deviation of sex- and age-matched controls. BASDAI (- 33%, p < 0.01) and BASMI (- 22%, p = 0.01) improved, but there was no improvement in aBMD, TBS, or microarchitecture. By HR-pQCT, vBMD decreased (- 0.6%, p = 0.04), and cortical porosity increased (8.3%, p = 0.03). New vertebral fractures were not observed.