Long-term osteoprotective effects of IL-17A blockade with secukinumab in psoriatic arthritis: data from the PSARTROS-II study

Objective To evaluate the long-term efficacy of interleukin (IL)-17A inhibition with secukinumab on structural bone changes and clinical outcomes in psoriatic arthritis (PsA). Methods We conducted a phase-IV non-interventional study on adult patients with active PsA using high-resolution peripheral quantitative CT (HR-pQCT) and MRI of the hand over 48 months. All participants received secukinumab treatment and were followed up according to clinical practice, with repeated HR-pQCT and MRI. Number and volume of erosions, bone density, cortical and trabecular microarchitecture and bone biomechanical properties were assessed based on HR-pQCT scans. MRI synovitis, tenosynovitis, osteitis, periarticular inflammation, erosions and osteoproliferation were quantified by Psoriatic Arthritis MRI Score (PsAMRIS)-Outcome Measures in Rheumatology (OMERACT) score. Study outcomes included drug survival and changes from baseline in disease activity, functional status and imaging-detected inflammation and damage. Results 32 patients with PsA (40.6% female, mean age 56±7.5 years) were enrolled. Drug survival rate was 68.8% at 48 months. Secukinumab was highly effective in all PsA disease domains, with significant improvements in Disease Activity Score 28 (p<0.001), Leeds Enthesitis Index (p=0.027), Psoriasis Area and Severity Index (p=0.001), C reactive protein (p=0.09), Psoriatic Arthritis Impact of Disease (p<0.001) and pain (p<0.001). Functional status measured by the Health Assessment Questionnaire remained stable. On HR-pQCT, bone density, microarchitecture and biomechanics were preserved. There was no progression of bone erosions (all changes were not significant). On MRI, PsAMRIS erosion and osteoproliferation subitems increased marginally (+1.4 and +0.8, respectively), while inflammatory changes remained stably low. No major safety signals emerged. Conclusion Multimodal imaging with HR-pQCT and MRI showed no relevant progression of structural bone damage over 48 months in patients with PsA treated with secukinumab, suggesting that anti-IL-17A therapy induces sustained osteoprotective effects in PsA.