Fibroblast Activation Protein–Targeted PET Imaging of Metastatic Castration-Resistant Prostate Cancer Compared With 68Ga-PSMA and 18F-FDG PET/CT

Abstract Herein we present 2 mCRPC (metastatic castration-resistant prostate cancer) patients who underwent 68 Ga-PSMA PET/CT for PSMA-targeted radioligand therapy eligibility. Prior studies have noted aggressive clinical behavior and poor prognosis associated with discordant FDG positivity and low PSMA expression. Accordingly, the patients also underwent 18 F-FDG PET/CT, which revealed intratumoral heterogeneity. Therefore, an additional PET/CT targeting fibroblast activation proteins (FAPs) using 68 Ga-FAPI-04 was performed to assess the potential for an FAP-targeted therapy. This report highlights the theranostic potential of FAP imaging in mCRPC, particularly in patients with heterogeneous tumor phenotypes.