JAK1 inhibition with filgotinib in axial spondyloarthritis: Key efficacy and safety findings

Could an oral JAK1 inhibitor change the treatment landscape for axial spondyloarthritis? Explore the phase 3 OLINGUITO trial presented at EULAR 2026.

The OLINGUITO trial (NCT05785611) was a phase 3, randomized, double-blind, placebo-controlled trial, investigating the efficacy and safety of filgotinib, a janus kinase (JAK)-1 inhibitor, in adults with active axial spondyloarthritis (axSpA).

In this interview, EULAR President Dr Xenofon Baraliakos (Rheumazentrum Ruhrgebiet, Herne, Germany) spoke with touchIMMUNOLOGY to discuss the mechanism of action of filgotinib and the rationale for its investigation in axSpA in the OLINGUITO trial. Dr Baraliakos also provides insight into the design, inclusion criteria and key findings from the phase 3 trial, while highlighting their potential clinical significance.

Abstract: Filgotinib significantly improves disease activity in patients with active axial spondyloarthritis: Primary results from the Phase 3 OLINGUITO trial. EULAR 2026, June 3– 6, London, UK.

touchIMMUNOLOGY coverage of EULAR 2026

My name is Xenophon Baraliakos. I am a rheumatologist working in Germany, with a special interest in axial spondyloarthritis and I was a Principal Investigator of the OLINGUITO trial on filgotnib in axial spondyloarthritis.

What is the mechanism of action of filgotinib and what was the rationale for its investigation in axSpA?

Filgotinib is a JAK1 inhibitor, a class of drug which targets multiple cytokines in one and inhibits the intracellular component of cytokine development. JAK1s should therefore be very efficacious in RMDs, where inflammation plays a key role in disease pathology. JAK inhibition has already been shown to be effective in axial spondyloarthritis, particularly JAK1 inhibition, as it is the strongest effect we may have in inflammatory pathways in axSPA.

The rationale was to investigate whether filgotinib would work as a strong anti-inflammatory drug after the failure of the more conservative or conventional treatments, such as nonsteroidal anti-inflammatory drugs (NSAIDs).

What were the aims, design, and inclusion criteria of the OLINGUITO trial?

The OLINGUITO trial tried to find out if filgotinib was effective in active axSPA. We included patients with a diagnosis of axSPA, who also fulfilled the 2009 ASAS classification criteria, and had active disease activity with a BASDAI score >4. They also had to have their BASDAI score increase, despite treatment in the past with NSAIDs, and have failed them or have not tolerated them.

We divided the study participants into two groups: radiographic and non-radiographic axSpA, representing patients who did or did not have conventional X-ray changes in the sacroiliac joints based on the stages of the disease, respectively. Agencies, such as the EMA, require this for showing that the drug is efficacious.

Participants assigned to the active drug received treatment for 16 weeks and were then followed up for at least 1 year. Those assigned to placebo received placebo for 16 weeks before switching to the active drug.

What were the primary and secondary endpoints and how well were they achieved?

The primary endpoint was the proportion of patients achieving an ASAS40 response (≥40% improvement according to the ASAS criteria) at Week 16, comparing filgotinib with placebo. Secondary endpoints included MRI inflammation, other disease activity measures, such as ASDAS scores and statuses, and improvement in CRP, functional impairment, and quality-of-life metrology.

The efficacy findings were clear with double the number of filgotinib-treated patients reaching the outcomes for both radiographic and non-radiographic groups. For the radiographic data, there were approximately 40% improvers at 14 weeks in the filgotinib trial arm compared to 20% in the placebo arm and for the non-radiographic group, it was 35% versus 15%, respectively.

There was a clear and statistically significant improvement in patients on active drug compared to those on placebo with all other secondary outcomes improved. Safety outcomes were according to the profile we already have for JAK inhibition.

What is the clinical significance of these findings?

These findings are extremely important and significant, because they demonstrate that JAK inhibition is efficacious and safe in axSPA. JAK inhibitors are certainly expanding the possibilities we have in the treatment of axSPA, beyond biologic DMARDs.

Another benefit of using JAK inhibitors is that they are currently the only way of treating patients orally, meaning that we are giving them more options for treatment in this disease. It is something that was long needed and increases the opportunities for patients to choose between injectables and oral treatments with similar efficacy between them.