Characterizing Breast Cancer With Al18F-NOTA-FAPI-04 PET/CT (PFB-02)

A Prospective Pilot Study to Explore Performance and Efficacy of Al18F-NOTA-FAPI-04 PET/CT in Breast Cancer Patients

Fibroblast activation protein (FAP) is overexpressed in cancer-associated fibroblasts (CAFs), which constitute a major proportion of cells within the tumor microenvironment, especially in breast cancer. Previous studies have demonstrated that FAPI PET/CT performs well in cases of epithelial tumors, including breast cancer. This prospective study is going to investigate the performance and value of Al18F-NOTA-FAPI-04 PET/CT in patients with breast cancer.

Breast cancer is a complex, heterogeneous disease comprising numerous distinct biological subtypes characterized by variant pathobiological features and clinical behaviors. 18F-fluorodeoxyglucose (18F-FDG) PET/CT, an essential imaging modality in the characterization of metabolism within the tumor, has successfully evolved in the diagnosis, staging, and assessment of treatment response in patients with breast cancer. Cancer-associated fibroblasts (CAFs) are a crucial component of the tumor stroma with diverse functions. Fibroblast activation protein (FAP), a type II membrane-bound glycoprotein from the dipeptidyl peptidase-4 family, is highly expressed in the CAFs of several epithelial carcinomas, including breast cancer, coupled with relatively low expression in normal tissue. Based on this characteristic, many small-molecule inhibitors of FAP (FAPIs) labeled with radioactive tracers (68Ga, 18F, or 177Lu) have been synthesized as theranostic radiotracers for cancer. Previous studies on FAPI PET/CT tumor imaging have focused on the 68Ga radionuclide rather than 18F. As 18F-labeled FAPI has more favorable physical properties, high production capacity, and good imaging characteristics, it may be an ideal agent for PET imaging. Therefore, this study aims to evaluate the performance and value of Al18F-NOTA-FAPI-04 PET/CT in patients with breast cancer.

Patients enrolled underwent PET/CT after injection of Al18F-NOTA-FAPI-04 to image lesions of breast cancer.

The maximum standard uptake value (SUVmax) was measured in the breast cancer lesions on Al18F-NOTA-FAPI-04 PET/CT.

The mean standard uptake value (SUVmean) was measured in the breast cancer lesions on Al18F-NOTA-FAPI-04 PET/CT.

Inclusion Criteria: suspected or confirmed untreated breast cancer; breast cancer patients after neoadjuvant chemotherapy; signed written consent. Exclusion Criteria: pregnancy; breastfeeding; any medical condition that in the opinion of the investigator may significantly interfere with study compliance.