⁶⁸Ga-FAPI-04 PET Provides Better Diagnostic Imaging for Malignant Colorectal Carcinomas Than ¹⁸F-FDG PET

Background: FDG high-uptake lesions indicate not only carcinoma but also benign lesions. The 68Ga-labelled FAPI was accumulated in various tumors. However, it’s unclear about the capacity of FAPI-PET in identifying malignant tumors from benign lesions.Methods: An AOM/DSS-induced rat colorectal tumor model was established. A double PET/CT tracer of 68Ga-FAPI-04 and 18F-FDG was used in the clinical trial and rat colorectal tumor model. Immunohistochemistry staining, enteroscopy, and radioautography were performed in this study.Results: Eight out of 22 patients had 18F-FDG-avid colorectal lesions, but they were negative in 68Ga-FAP-04 PET imaging. 68Ga-FAPI PET imaging distinguishes neoplasia from inflammatory lesions in an AOM/DSS-induced rat colorectal tumor model, and FAPI accumulation gradually increases along with tumor progression. Moreover, the clinical study demonstrated that only 20.5% (16 out of 78) of premalignant/benign lesions were weak FAP-positive. However, most cancer patients (85.1%, 80 out of 94) were FAP-positive, which further supported the above findings. Conclusion: The 68Ga-FAPI-04 PET distinguishes malignant tumors from inflammatory lesions by detecting FAP in a rat colorectal tumor model and the clinics, suggesting that 68Ga-FAPI-04 PET is a better diagnostic tool than 18F-FDG PET, at least to colorectal cancer patients.Funding Information: This study was supported by grants from the Ministry of Science and Technology of the People's Republic of China (2018YFC1313205), the Shanghai Committee of Science and Technology (11DZ2260200) (20JC1410100) and the National Natural Science Foundation of China (81572300) (81872342) to Dr. Mi; the National Natural Science Foundation of China (81801725) to Dr. Shangguan. Declaration of Interests: The authors state that no conflict of interest to disclose.Ethics Approval Statement: This study received animal ethics board approval at Shanghai Jiao Tong University School of Medicine, and clinical ethics board approval at the Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine.