A novel PET tracer targeting inflamed blood vessels shows significant promise as a biomarker for giant cell arteritis. A first-in-human study demonstrates the imaging agent successfully tracks vascular disease activity and diminishes as steroid treatments take effect.
Measuring vasculitis activity remains clinically difficult because current diagnostic tools lack specificity for live vascular inflammation. This new tracer targets vascular adhesion protein-1, or VAP-1, a molecule transported to the vessel surface specifically during inflammatory episodes.
Researchers conducted a proof-of-concept trial involving eight newly diagnosed patients, eight relapsing patients, and eight healthy controls. Participants underwent specialized PET/CT scanning alongside vascular ultrasound. The team also assayed soluble VAP-1 and matrix metalloproteinases to identify candidate markers of vascular inflammation.
Tracer uptake correlated positively with artery wall thickness measured by ultrasound. Crucially, prednisolone exposure linked inversely to vascular uptake, confirming the biomarker responds to therapeutic intervention. While MMP9 levels were markedly higher in newly diagnosed cases, soluble VAP-1 was lower than in relapsing patients.
Investigators conclude this molecular imaging tool detects active inflammation and monitors treatment efficacy. Although the cohort was small, the findings suggest a functional biological axis driving the imaging signal. Larger studies are now required to validate its utility across the broader giant cell arteritis spectrum.