Diagnosing, treating and monitoring the inflammatory endotype in osteoarthritis clinical trials

Osteoarthritis (OA) involves an inflammatory component, presenting as synovitis and systemic low-grade inflammation. Preliminary evidence suggests that anti-inflammatory treatments may offer symptomatic and structural benefits in OA. More targeted approaches have been proposed and tested, but the means of identifying the clinical and molecular characteristics of patients with an inflammatory subtype remains unclear. Emerging evidence suggests that subsets of OA patients with significant inflammatory features, such as elevated systemic and synovial cytokine levels (e.g. IL-1, TNF-α), imaging confirmed synovitis, or tissue remodeling biomarker signatures may respond more favorably to anti-inflammatory treatments.

We provide a perspective on recent evidence supporting the existence of a clinically actionable inflammatory molecular endotype of OA. We integrate key advances from recent clinical studies, biomarker consortium datasets and imaging models, to outline potential tools for single-patient endotyping, and highlight practical considerations for recognizing an inflammatory endotype in the clinical trial setting.

Challenges remain in standardizing tools for identifying these patients. Current methodology, including imaging and soluble biomarkers, are not yet been widely adopted in clinical practice. An improved understanding of the inflammatory endotype will be key for improving clinical trial design and identifying patient subpopulations more likely to benefit from targeted treatment.