Preliminary Findings of the Role of FAPi in Prostate Cancer Theranostics

Abstract

Prostate cancer (PCa) is the most frequently diagnosed cancer worldwide and the second most common cause of cancer-related deaths among men. Progress in molecular imaging has magnified its clinical management; however, an unmet clinical need involves the identification of new imaging biomarkers that complement the gold standard of prostate-specific membrane antigen (PSMA) positron emission tomography (PET) in cases of clinically significant PCa that do not express PSMA. Fibroblast activation protein (FAP) is a type II transmembrane serine overexpressed in many solid cancers that can be imaged through quinoline-based PET tracers derived from an FAP inhibitor (FAPi). Preliminary results of FAPi application in PCa (in PSMA-negative lesions, and in comparison with fluorodeoxyglucose—FDG) are now available in the literature. FAP-targeting ligands for PCa are not limited to detection, but could also include therapeutic applications. In this preliminary review, we provide an overview of the clinical applications of FAPi ligands in PCa, summarising the main results and highlighting contemporary strengths and limitations.

A Critical Analysis of the Robustness of Radiomics to Variations in Segmentation Methods in 18F-PSMA-1007 PET Images of Patients Affected by Prostate Cancer

“…PCa often demonstrates varying levels of aggressiveness across different regions of the tumor due to its inherent heterogeneity [29]. To quantify this variation, a grading system is used to assign grades to the two primary areas of cancerous tissue under examination, and the sum of these grades determines the overall Gleason score (GS).…”

Diagnostic yield of FAP-guided positron emission tomography in thyroid cancer: a systematic review

“…CAFs, also known as reactive fibroblasts or myofibroblasts, are found in a variety of malignant tumours, including head and neck malignancies other than TC ( 20 , 21 ). FAP expression may also variate according to the solid tumours’ grading, such as in prostate cancer ( 22 , 23 ). Despite CAFs being stromal cells, which are part and parcel of neoplastic lesions, they do not express epithelial, endothelial, or leukocyte markers and are notably devoid of oncogene mutations ( 24 ).…”

Head-to-Head Comparison of FDG and Radiolabeled FAPI PET: A Systematic Review of the Literature

“…On the other side, labeling FAPI with 18 F, that has a longer half-life and lower positron energy than 68 Ga (half-life of 110 and positron energy of 0.65 MeV vs. 68 and 1.9 MeV), would reduce the costs of production and facilitate its distribution together with improved spatial resolution [26]. Furthermore, besides the use of radiolabelled FAPI tracers for diagnostic purposes, DOTA chelator in the molecular structure allows the coupling of FAPI molecules with either alpha-or beta-emitting radioisotopes (i.e., Lutetium-177, Yttrium-90, Actinium-225), exploiting their potential role as a new anti-cancer radioligand therapy (RLT) in a theranostic perspective [23,24,27]. Like [ 18 F]FDG, wound healing, fibrosis and inflammation can be visualized using FAPI-based tracers PET imaging [25].…”