Preclinical Evaluation and First-in-Human Imaging with ¹⁸ F-NOTA-R49: A Comparative Analysis versus ¹⁸ F-FDG PET/CT in Various Cancer Patients

Our study aims to develop a novel ¹⁸F-labeled fibroblast activation protein inhibitor (FAPI) probe, ¹⁸F-NOTA-R49, and validate its diagnostic performance across multiple cancers in both preclinical and clinical studies. ¹⁸F-NOTA-R49 was synthesized through chemical methods, and its in vitro affinity, internalization characteristics, and specificity were evaluated in FAP-overexpressing cells HEK-293-hFAP and U-87 MG. Tumor-bearing mouse models were established to assess in vivo targeting and pharmacokinetics via small-animal PET/CT imaging and biodistribution studies. Ten patients with various cancers were enrolled in a clinical study comparing lesion-detection capabilities of ¹⁸F-NOTA-R49 and ¹⁸F-FDG PET/CT. In vivo studies showed significant early uptake in FAP-positive tumors (29.36 ± 1.49%ID/g at 0.5 h), which was effectively blocked by unlabeled NOTA-R49. Clinically, ¹⁸F-NOTA-R49 exhibited superior lesion contrast compared to ¹⁸F-FDG in gastric cancer, mesenchymal tumors, prostate cancer, seminoma, and pancreatic cancer, particularly in peritoneal and lymph node metastases. ¹⁸F-NOTA-R49 demonstrates high affinity and specificity and excellent tumor-targeting properties. It shows better diagnostic efficacy than ¹⁸F-FDG in various malignant tumors, indicating a significant clinical translation potential.