Background/Purpose: The efficacy of ixekizumab (IXE), a selective interleukin-17A antagonist, was assessed in patients (pts) with axial SpA (axSpA) in three Phase 3, randomized, double-blind, placebo (PBO)-controlled trials, COAST-V, COAST-W and COAST-X. The BASDAI is frequently used by clinicians to measure disease activity and response to treatment in pts with axSpA, and when considering starting biologic DMARD therapy^1,2. We present BASDAI and quality of life (QoL) outcomes at 16 weeks from the COAST trials.

Methods: COAST-V (NCT02696785) and COAST-W (NCT02696798) assessed pts with radiographic axSpA, and COAST-X (NCT02757352) assessed pts with non-radiographic axSpA. All pts fulfilled Assessment of Spondyloarthritis International Society (ASAS) classification criteria for axSpA. Pts were either biologic-naive (COAST-V, COAST-X) or TNFα inhibitor-experienced (COAST-W) and were randomized to IXE (80 or 160 mg at week 0 then 80 mg every 2 or 4 weeks [Q2W, Q4W]) or PBO or adalimumab (ADA, 40 mg Q2W; COAST-V only). Treatment response at week 16 was assessed by the proportion of patients achieving BASDAI< 4, 50% reduction from baseline in BASDAI (BASDAI50), and a clinically meaningful change from baseline in BASDAI of at least 2 units (ΔBASDAI≥2)^1,2. Categorical variables were analyzed by logistic regression with non-responder imputation (NRI) for missing data. QoL was assessed by change from baseline in Short Form (SF)-36 Physical Component Summary (PCS) scores according to BASDAI< 4 response status at week 16; missing data were imputed using modified baseline observation carried forward (mBOCF).

Results: In total, 341 pts from COAST-V, 316 from COAST-W, and 303 from COAST-X were included in this analysis. At week 16, a greater proportion of pts treated with IXE achieved BASDAI< 4, BASDAI50, and ΔBASDAI≥2 (Figure 1) compared to PBO across all three trials, and the difference was statistically significant for the majority of endpoints. Furthermore, pts achieving BASDAI< 4 showed greater improvements in SF-36 PCS scores (Figure 2).

Conclusion: In the COAST trials, IXE delivered clinically meaningful improvements in pts with axSpA after 16 weeks of treatment. Low disease activity (BASDAI< 4) was achieved with IXE regardless of axSpA type (radiographic or non-radiographic) or prior use of TNFα inhibitors. Achieving BASDAI< 4 was associated with greater improvements in physical QoL.

1. Magrey MN, Kiltz U. Chapter 9 in Axial Spondyloarthritis. Elsevier, 2019:121-133.
2. van der Heijde D, et al. Ann Rheum Dis 2017;76:978-991.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/achievement-of-low-disease-activity-according-to-basdai-with-ixekizumab-in-patients-with-axial-spondyloarthritis-16-week-results-from-the-coast-trials/