Model Predicts Persistent Arthritis After Checkpoint Inhibitor Therapy

Elevated c-reactive protein (CRP), tenosynovitis on imaging, and a specific peripheral inflammatory pattern on MRI predict which patients with immune checkpoint inhibitor (ICI)-induced joint disease will develop persistent symptoms, according to new data presented at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress in London.^1,2

Kate Harnden, MBChB, of the Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, discussed the work in an interview with Rihards Buss, MD, consultant rheumatologist at Freeman Hospital in Newcastle, for RheumatologyLive's Joint Ventures series.

"It is a really complicated area because any treatment we give these patients in terms of immunosuppression will theoretically do the opposite of what the immune checkpoint inhibitor is doing for their cancer,” Harnden said.

Building the Predictive Models for Persistent Arthritis

Harnden's group has followed a Leeds cohort of > 200 patients with ICI-induced inflammatory arthritis (ICI-IA) or arthralgia over the past 5 years, a design she noted is distinctive for including arthralgia patients rather than only those with overt inflammatory arthritis. Patients enrolled for ≥ 6 months were invited back for a final follow-up visit assessing persistent symptoms and DMARD requirement, defined in part by an inability to taper steroids below 10 mg of prednisolone or equivalent.

At a median follow-up of 16 months, about 57% of patients had persistent symptoms, with patients experiencing arthralgia showing similar persistence rates to those with inflammatory arthritis. Harnden said this overlap is clinically important given that arthralgia may affect up to 6 times as many patients as inflammatory arthritis. Two multivariable models, developed from the cohort, identified elevated CRP, tenosynovitis on imaging, and a rheumatoid arthritis-like peripheral inflammatory pattern on whole-body MRI as factors associated with both symptom persistence and DMARD need.

Immunotherapy Status Did Not Predict Arthritis Persistence

Unlike prior research restricted to patients who had already stopped immunotherapy, Harnden's model incorporated immunotherapy status at baseline and found no significant association between continuing or stopping treatment and symptom persistence. Some patients improved while still on immunotherapy, while others had persistent arthritis long after stopping it.

“We want to develop these multivariable models further, looking specifically at if there's any certain biomarkers that we can add into these models to improve their accuracy,” Harnden said.

References

1. Buss R, Dyball S, and Harnden K. Joint Ventures: Lupus Health Inequalities, Growing Burden of ICI-Arthritis at EULAR 2026. RheumatologyLive. Published June 26, 2026. Accessed September 2, 2026. https://www.rheum-live.com/view/joint-ventures-lupus-health-inequalities-growing-burden-ici-arthritis-eular-2026

2. Harnden K, Sharrack S, Sugden H-J, et al. Predicting the outcomes of immune checkpoint inhibitor-induced inflammatory arthritis and arthralgia: development of multivariable models to predict disease persistence [abstract POS0147]. Presented at: European Alliance of Associations for Rheumatology (EULAR) Annual Congress 2026; June 3–6, 2026; London, United Kingdom. doi:10.1136/annrheumdis-2026-eular.B.1618