A novel diagnosis strategy for chronic inflammatory bowel diseases using immuno-PET of [89Zr]Zr-IL-23p19 antibody

Inflammatory bowel disease (IBD) is a chronic inflammatory condition requiring accurate and non-invasive imaging for diagnosis and monitoring. Current clinical methods, including Disease Activity Index (DAI) scoring, have limitations due to their subjectivity and inability to detect mild or early inflammation. This study introduces a novel ⁸⁹Zr-labeled IL-23p19 monoclonal antibody ([⁸⁹Zr]Zr-IL-23p19) for targeted immuno-PET imaging in a dextran sulfate sodium-induced murine IBD model. Radiolabeling of IL-23p19 antibody with [⁸⁹Zr]Zr yielded a stable tracer with high radiochemical purity. PET/MR imaging showed focal accumulation of [⁸⁹Zr]Zr-IL-23p19 in inflamed colonic regions, aligning closely with histological inflammation and IL-23p19 expression. In contrast, the previous metabolic tracer [¹⁸F]FSPG demonstrated diffuse uptake without clear localization to inflamed tissues. Quantitative PET analysis indicated a significant correlation between [⁸⁹Zr]Zr-IL-23p19 uptake and DAI scores, whereas [¹⁸F]FSPG exhibited weak correlations. These results highlight [⁸⁹Zr]Zr-IL-23p19 immuno-PET imaging as a sensitive, specific, and non-invasive biomarker with strong potential for clinical translation in diagnosing and monitoring chronic intestinal inflammation in patients with IBD.