Dual-Targeting Antibody for axSpA (IL-17A + TRBV9+ T Cell Depletion)

Hi, I'm Anthony Chan here at ACR 2026 in Orlando reporting for RheumNow. A lot has been spoken about cellular therapies in many of the other conditions other than axSpA, and today we actually have a presentation that looks at cellular therapies in the area of axSpA. This is looking at CD8 cells and how by blocking some of these cells there might actually be a possible treatment for the future, and this is from abstract 2941. The agent is called FTB-918, and I am with Artal Dioda, who actually was the presenter of this abstract. Very welcome to RheumNow.

Thank you. Thank you. So tell us a little bit about this — which is very exciting — FTB-918.

It certainly is very exciting. The whole field of axSpA therapy is moving in that direction. We are now moving from cytokine/anti-cytokine therapy to cellular therapy, and this is based on the findings that patients who are HLA-B27 positive — and that HLA-B27 molecule is presenting probably a peptide derived from the gut — and it's being presented to CD8-positive T-cells. When people started to explore the CD8-positive T-cell receptor, they found out there is one particular motif, and that is TRBV9. So TRBV9 is T-cell receptor beta chain V9. And on the alpha chain they found another one, TRAV21.

They found out that patients with axial spondyloarthritis who are HLA-B27 positive — and this was found, by the way, not only in Caucasian people but in a completely different population of Chinese axSpA people who are HLA-B27 positive — their T-cell receptors had this motif TRBV9 and TRAV21. And so this cellular therapy, FTB-918, is a monoclonal antibody that on one side would actually attach itself to the TRBV9, which is on the CD8-positive T-cell. By the way, there are only 3% of the CD8-positive T-cells which are this. So because this antibody is going to kill them — and people get worried about T-cell killing — it is only 3% of the CD8-positive T-cells.

It's a monoclonal antibody: on one side it'll attach to the TRBV9, and through antibody-dependent cell-mediated cytotoxicity — ADCC — the natural killer cell will kill that CD8-positive T-cell. And on the other side, this molecule has an IL-17 nanobody. So it's a very interesting thing, because axial spondyloarthritis, apart from having this CD8-positive T-cell interaction and this antigen presentation, also has the anti-cytokine component — we don't really want to forget that. So this is a dual-action monoclonal antibody.

What I presented — we don't have human data — so what I presented was non-human primate data and in vitro data. The studies on this very exciting therapy will start in early next year.

It's very exciting, certainly in the field of axSpA. Just tell us — why is there a need for it to be a dual action? Why do you need to attach the IL-17 to it instead of infusing IL-17, for example?

The idea was — the company which is producing this — there is only one study from Russia which actually showed that anti-TRBV9 therapy works, and there is no other proof. So the reason to add the IL-17 molecule is that we will definitely — this therapy, this particular molecule, is going to work at least from an IL-17 point of view. They will then be looking at how many of the CD8-positive T-cells that are TRBV9-positive in the patient's blood were destroyed or killed by this. To answer your question directly, I think it was to ensure that this particular molecule will work in patients with axSpA, because you get direct engagement, and the IL-17 is also acting on the cell — exactly — and it's a nanobody, so patients will get double benefits.

Yeah, so very exciting for the field of axSpA going forward. We're certainly very excited to hear more about the study. So you think there'll be more work coming out soon?

There are several companies looking at TRAV21/TRBV9 combined combination therapy, etc. So the field is moving in that direction.

That's very good news for axSpA, especially in our community, to have some cellular therapy as well. Thank you for taking the time to explain to us what is a very exciting program going forward. I'm Anthony Chan reporting here for RheumNow at ACR 2026 in Orlando.