Rheumatology · Clinical trials
Axial Spondyloarthritis Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About axial spondyloarthritis — and why its trials are hard
Axial spondyloarthritis (axSpA) is a chronic inflammatory disease of the axial skeleton and sacroiliac joints, spanning radiographic disease (ankylosing spondylitis) and non-radiographic axSpA, typically presenting with inflammatory back pain, stiffness, and, over time, structural change. NSAIDs are first-line. When they fail, biologics and targeted synthetics are used: TNF inhibitors (adalimumab, etanercept, infliximab, certolizumab) were the foundational advance, followed by interleukin-17A inhibitors (secukinumab, ixekizumab), the dual IL-17A/F inhibitor bimekizumab, and oral JAK inhibitors (upadacitinib). Notably, unlike in psoriatic arthritis, the IL-12/23 and IL-23 pathways failed in axSpA: ustekinumab's phase 3 program and risankizumab's trial did not beat placebo, and IL-6 inhibition (tocilizumab, sarilumab) also failed. The pivotal efficacy endpoint is ASAS40 (a 40% Assessment of SpondyloArthritis International Society response) at around week 12-16, complemented by ASAS20, BASDAI, ASDAS, spinal mobility, and MRI inflammation. These divergent results have made axSpA a textbook lesson in pathway specificity.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Adalimumab (Humira) | 2006 | Active ankylosing spondylitis (later nr-axSpA); TNF inhibitor | ATLAS | ASAS20 (primary); ASAS40 secondary | ASAS20 ~58% vs ~21% placebo at week 12 |
| Secukinumab (Cosentyx) | 2016 | Active ankylosing spondylitis (later nr-axSpA); IL-17A inhibitor | MEASURE 1 and MEASURE 2 | ASAS20 (primary); ASAS40 secondary | MEASURE 2 ASAS20 ~61% vs ~28% placebo at week 16 |
| Ixekizumab (Taltz) | 2019 | Active ankylosing spondylitis and nr-axSpA; IL-17A inhibitor | COAST-V (biologic-naive) | ASAS40 at week 16 | ~48% vs ~18% placebo |
| Upadacitinib (Rinvoq) | 2022 | Active ankylosing spondylitis (and nr-axSpA); oral JAK inhibitor | SELECT-AXIS 1 | ASAS40 at week 14 | ~52% vs ~26% placebo |
| Bimekizumab (Bimzelx) | 2024 | Active axSpA (radiographic and non-radiographic); dual IL-17A/F inhibitor | BE MOBILE 1 and BE MOBILE 2 | ASAS40 at week 16 | Significantly higher ASAS40 vs placebo (approximately 45-47% vs ~13-21%) |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in axial spondyloarthritis development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Ustekinumab — Phase 3 axSpA program (Mease et al., Arthritis & Rheumatology 2019) | Trials terminated for futility after failing to separate from placebo on ASAS endpoints | The IL-12/23 (p40) pathway does not appear to drive axial inflammation, a striking contrast to its efficacy in psoriatic arthritis and psoriasis |
| Risankizumab — Phase 2 study in active ankylosing spondylitis (IL-23 p19 inhibitor) | Did not demonstrate meaningful benefit over placebo; axSpA development was not pursued | Confirms that selective IL-23 inhibition is ineffective in axial disease despite working in peripheral psoriatic arthritis |
Choosing the right endpoint
Primary endpoints that matter in axial spondyloarthritis trials
- ASAS40 — 40% improvement in ASAS response criteria; the primary efficacy endpoint for newer axSpA agents at ~week 12-16.
- ASAS20 — 20% ASAS response, the primary endpoint in earlier TNF and IL-17 pivotal trials.
- ASDAS / BASDAI — Composite disease-activity indices (ASDAS incorporates CRP) used to define low disease activity and response.
- MRI SPARCC / spinal mobility — Objective inflammation on MRI and mobility measures (e.g., BASMI) supporting the clinical endpoints.
How iNGENū runs axial spondyloarthritis trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Axial Spondyloarthritis clinical trials — FAQs
What is the standard efficacy endpoint in modern axSpA trials?
Why do IL-23 inhibitors work in PsA but not axSpA?
What options exist when TNF inhibitors fail?
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