Background: Systemic inflammation leads to decreased bone mineral density and altered bone microstructure in patients with psoriatic arthritis (PsA) and subclinically in high-risk psoriasis (PsO) patients [1, 2]. Recent evidence suggests that bDMARDs may protect bone by suppressing cytokine release. The PSoriasis and psoriatic ARTHRitis bOne imaging program (PSARTROS) investigates the long-term effects of IL-17A inhibition (IL17i) on inflammation and bone changes in PsA and PsO. We previously reported on the first 20 patients who underwent 24 weeks of secukinumab therapy. Structural bone changes in the hand assessed by magnetic resonance imaging (MRI) and high-resolution peripheral quantitative computed tomography (HR-pQCT) showed no progression, suggesting that IL-17 inhibition may slow catabolic and anabolic bone changes in PsA [3]. Here, we present the long-term clinical and imaging follow-up of the PSARTROS cohort over at least 24 months after starting therapy.

Objectives: To evaluate the long-term drug survival and efficacy of IL17i with secukinumab on clinical parameters and on structural bone and inflammatory changes in PsA and PsO using MRI and HRpQCT over 48 months.

Methods: We established a single-arm prospective exploratory open-label study. PsA patients fulfilling the CASPAR classification criteria and PsO patients with baseline subclinical changes at MRI and/or HRpQCT but no evidence of clinical PsA were included. All patients received therapy with 150 mg or 300 mg secukinumab. Concomitant treatment with csDMARDs and glucocorticoid was allowed. Clinical examination including disease activity parameters, PROMs, and MRI and HRpQCT scans of the dominant hand were performed at baseline, 12 weeks, 24 weeks, and according to clinical practice hereafter up to at least month 48. We used mixed-effects models and generalized additive models to compare parameter at multiple time points, where appropriate. Kaplan-Meyer curves were generated for survival analysis.

Results: The study recruited 32 participants (19 male, 59.4%; 13 female, 40.6%) with a mean age of 55 (SD=9.5) years. Participants had a high average BMI of 28.2 (SD=4.5) kg/m². The mean duration of PsA was 4.2 (SD=3.3) years. At baseline, patients exhibited high disease activity across all PsA domains (Table 1). The mean follow-up was 48.0 (SD=14.2) months. 10 subjects (31.2%) discontinued treatment before reaching 48 months, resulting in a 4-year drug survival rate of 68.75% (Figure 1). Another 10 (31.2%) interrupted treatment after 48 months, while 12 (37.5%) continued treatment throughout all follow-up. Median treatment duration before discontinuation was 46.0 months, with a mean of 48.0 (SD=14.2). Discontinuation was mainly due to loss of efficacy (75%), lasting remission (20%), and patient preference (5%). No cases therapy interruption due to primary inefficacy or adverse events were observed. By the end of follow-up there was a significant decrease in DAS28 (p=0.009), LEI (p=0.023), PASI (p=0.017) and Pain (p=0.030) compared to baseline. Observing the course of clinical parameters, we observed a substantial and rapid improvement within the first 12 months, which was maintained until month 36. However, pain and DAS8 increased again significantly between months 36 and 48 negating part of the beneficial effects (Table 1). A total of 202 radius and metacarpophalangeal joints (MCPs) HR-pQCT measurements were performed, each patient contributing an average of 6.3 (SD=2.6) scans. Over 48 months of follow-up, no significant changes were observed in bone mineral density, microstructure, and biomechanics at either radius or MCPs. The number and volume of erosions remained stable as well (Table 1). A total of 92 hand-MRI measurements were conducted, each patient providing an average of 2.9 (SD=2.1) scans. Over 48 months, we observed a slight increase in PsAMRIS bone erosion (p=0.011) and bone proliferation scores (p=0.003). Synovitis, osteitis, tenosynovitis, and periarticular inflammation remained stable (Table 1).

Conclusion: In our study, secukinumab demonstrated excellent long-term tolerability and clinical efficacy across all major disease domains over 48 or more months, with a 4-year drug survival rate of nearly 70%. Significant improvements in DAS28, LEI, PASI, and pain were sustained for 36 months, with a slight increase thereafter. Notably, bone density, microstructure, and biomechanics measured by HRpQCT remained remarkably stable. Conversely, MRI showed slight structural progression at sites other than the MCPs and radius. Nonetheless, this progression occurred without worsening disease activity or disability and over a very extended time, suggesting limited impact on function and a possible role of aging. In conclusion, our study shows that secukinumab is a well-tolerated and effective long-term treatment for PsA. Our multimodal imaging data suggest that IL-17i therapy has osteoprotective effects in PsA, with the potential of slowing down disease progression. This is in line with the findings of our previous report (3) and suggests that osteoprotective effects similar to those observed under anti-TNF treatment in rheumatoid arthritis (4) may be induced by IL17i therapies in PsA.

REFERENCES: [1] Simon D, et al. Arthritis & Rheumatology (2022).

[2] Wu D, et al. Osteoporosis International (2020).

[3] Kampylafka E, et al. Arthritis research & therapy (2018).

[4] Lange U, et al. Rheumatology (2005).

Figure 1.

Kaplan-Meyer curve of the on-drug survival on secukinumab during the extended follow-up of the PSARTROS study.

Table 1. Change in the clinical, HR-pQCT and MRI parameters under secukinumab therapy over the 48-weeks follow-up.

Acknowledgements: NIL.

Disclosure of Interests: Alp Temiz: None declared, Louis Schuster: None declared, Melek Yalcin Mutlu: None declared, Koray Tascilar: None declared, Sara Bayat COI not relevant to this abstract, COI not relevant to this abstract, Jürgen Rech COI not relevant to the abstract, COI not relevant to the abstract, JR recieved financial support from Novartis for the conduction of this study, Axel Hueber COI not relevant to this study, COI not relevant to this study, COI not relevant to this study, Arnd Kleyer COI not relevant to this study, COI not relevant to this study, COI not relevant to this study, David Simon COI not relevant to this study, COI not relevant to this study, DS recieved financial support from Novartis for the conduction of this study, Georg Schett COI not relevant to this study, COI not relevant to this study, COI not relevant to this study, Filippo Fagni COI not relevant to this study, FF recieved financial support from Novartis for the conduction of this study.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.