BACKGROUND: Ankylosing spondylitis (AS) is a chronic arthritic disease associated with pain and functional deterioration. Patients with active AS and an inadequate response to conventional therapy can be treated with several licensed biologic agents including tumour necrosis factor alpha (TNFα) inhibitors and secukinumab, a first-in-class, fully human interleukin-17A inhibitor. However, treatment guidelines highlight the importance of assessing response to biologics after 12 weeks and only continuing treatment if there is clear evidence of response. Secukinumab has been demonstrated to significantly improve the signs and symptoms of AS in two randomised controlled trials, MEASURE 1 and MEASURE 2. This analysis aimed to assess the importance of response status at 12 weeks as an indicator of longer-term outcomes with secukinumab 150 mg in TNFα inhibitor-naïve and TNFα inhibitor inadequate responder (primary or secondary treatment failure, contraindications, or intolerance) patients (TNFα-IR).
METHODS: Across MEASURE 1 and MEASURE 2,590 patients with active AS were randomised (1:1:1) to receive secukinumab 150 mg (n=197), 75 mg (n=197) or placebo (n=196), stratified by prior TNFα inhibitor status. The proportion of patients with a 50% reduction from baseline in the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI 50) at week 12 was determined. In this post-hoc analysis, mean absolute BASDAI and Bath Ankylosing Spondylitis Functional Index (BASFI) scores over time for secukinumab 150 mg and placebo patients were assessed independently by BASDAI 50 response at week 12 and prior TNFα inhibitor status.
RESULTS: Both BASDAI 50 responders and non-responders showed reductions in BASDAI and BASFI scores up to week 104 (Table 1). However, markedly greater reductions were observed for responders compared with non-responders over this time. For secukinumab 150 mg BASDAI 50 responders, mean BASDAI and BASFI scores were <2 (0-10 scale) at week 12 for both TNFα inhibitor-naïve and TNFα inhibitor-IR patients. Amongst both secukinumab 150 mg and placebo non-responders, mean BASDAI and BASFI scores at week 12 remained >4, regardless of prior TNFα inhibitor status.
CONCLUSION: Patients with a BASDAI 50 response at week 12 were associated with markedly better 2-year outcomes in BASDAI and BASFI scores than non-responders, irrespective of prior TNFα inhibitor status.
