Effects of TNF-α inhibition secukinumab on active ultrasound-confirmed enthesitis in psoriatic arthritis

Introduction: Enthesitis is a hallmark of psoriatic disease, but its clinical assessment is problematic in terms of diagnostic sensitivity and overlap with other comorbid conditions. Ultrasound is a useful tool that can give a more detailed assessment of enthesitis. Research demonstrates that those with persistent ultrasound entheseal disease are at risk of progressive articular damage. With limited data to guide choice between biologic therapy for psoriatic arthritis (PsA) patients, we wanted to assess the response of ultrasound-confirmed enthesitis to different forms of biologic therapies and study its utility in making more informed decisions. Methods: This was an open label observational study including patients aged ⩾18 years, who fulfil the classification criteria for PSA (CASPAR) and were due to commence on their first biologic therapy. The primary outcome was the change in MAdrid Sonographic Enthesitis Index (MASEI) score at 16 weeks of treatment. The MASEI score was also modified to assess the active elementary lesions (ActiveMASEI). Results: In all, 80 PsA patients were enrolled with 75 patients completing the study [secukinumab n = 23 and tumour necrosis factor inhibitor (TNFi) n = 52]. The mean reduction in MASEI score after 16 weeks of treatment was 3.42 with TNFi versus 1.74 with secukinumab ( p = 0.097). There was a significant difference in the change in the MASEIActive score for TNFi versus secukinumab (4.37 versus 2.26; p = 0.030) and this difference was more pronounced when only power Doppler signal within 2 mm of the enthesis insertion was included (4.37 versus 2.00; p = 0.007). Clinical outcomes were similar for both classes of biologic apart from a significant reduction in regards to the Dermatology Life Quality Index and Psoriasis Area and Severity Index score with secukinumab versus TNFi. Conclusions: We have for the first time compared the effect of ultrasound-confirmed enthesitis between different forms of biologic therapies for PsA. We have seen an overall improvement in entheseal scores for both classes of medications and demonstrated a larger reduction in active entheseal disease for TNFi versus secukinumab that merits further exploration.