SAT0292 Evaluation of radiographic progression after 4 years of etanercept (ETN) in ankylosing spondylitis (AS): results from the open-label extension (OLE) of the phase 3 clinical trial
Authors: N. Haroon, R.D. Inman, M. Fairbairn
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> ETN was well tolerated and showed clinical efficacy (ASAS 20: ETN 59%, placebo 28%, p&lt;0.0001) through 24 wks in a phase 3 AS trial;<sup>1</sup> efficacy was sustained up to 2 years in pts who completed the study and continued ETN in an OLE.<sup>2</sup> No significant difference was found in change in modified Stoke AS Spine Score (mSASSS) from baseline (BL) to yr 2 of the OLE among ETN-treated pts vs a historic cohort not treated with tumour necrosis factor inhibitors (TNFi).<sup>3</sup> <h3>Objectives</h3> Report radiographic progression through 4 years in ETN-treated pts with AS. <h3>Methods</h3> In the double-blind, placebo-controlled phase 3 study, pts with active AS were randomised to ETN 25 mg BIW or placebo for 24 wks. Pts who completed the study could enrol in a 168-wk OLE and were treated with ETN 25 mg BIW (amended after 17 months to 50 mg QW). The primary radiographic endpoint was change in mSASSS from BL to yr 2 vs change in mSASSS from yr 2 to yr 4. <h3>Results</h3> 257 pts were treated in the OLE, of whom 126 (49.0%) completed the study and 131 (51.0%) withdrew prior to 168 wks (most common reasons [&gt;5%]: pt refusal [10.1%]; adverse event, infection, or injection-site reaction [8.2%]; lack of efficacy [7.8%]). ETN resulted in sustained improvement in signs and symptoms of active disease for up to 168 wks beyond the 24-wk double-blind study. Of 267 pts who received ≥1 dose of ETN in the phase 3 study or OLE, 124 were included in the 4 year primary radiographic endpoint analysis (8 received a prohibited TNFi and were excluded). BL characteristics were similar between these pts and all pts who received ≥1 dose of ETN in the phase 3 study. Mean change in mSASSS among completers was 1.96 from BL to yr 4 (n=110) while change in mean mSASSS between yr 2 and yr 4 was 0.66 (n=109). The nominal p-value for change in mSASSS from BL to yr 2 vs change from yr 2 to yr 4 was 0.0536. Radiographic data suggest disease progression continued in pts receiving ETN continuously over 4 years; however, mean mSASSS increased from BL to year 2 and not from yr 2 to yr 4 (figure 1) due to a few outlier patients with large mSASSS values at yr 2 but missing 4 year data. <h3>Conclusions</h3> This is the first report of 4 year radiographic ETN data in AS, and these data suggest that disease progression continued in pts who received ETN continuously throughout, but that disease progression may be slower after longer-term treatment with ETN vs shorter term. This adds to the already-existing data that demonstrate TNFi seem to reduce radiographic progression in pts with AS. <h3>References</h3> [1] Davis Arthritis Rheum2003. [2] Davis Ann Rheum Dis2005. [3] van der Heijde Arthritis Rheum2008. <h3>Acknowledgements</h3> Study supported by Amgen, Inc. Medical writing assistance provided by BlueMomentum, an Ashfield Company, and funded by Amgen, Inc. <h3>Disclosure of Interest</h3> N. Haroon Consultant for: Abbvie, Amgen, Janssen, Merck, Novartis, UCB, R. Inman Consultant for: Amgen, Abbvie, Janssen, Merck, Novartis, M. Fairbairn Shareholder of: Amgen, Employee of: Amgen