Current Status of Fibroblast Activation Protein Imaging in Gynecologic Malignancy and Breast Cancer.

68Ga-FAPI-PET/computed tomography (CT) is a novel PET/CT radiotracer particularly developed for oncologic imaging. Gynecologic malignancies comprise a broad spectrum of entities and, along with breast cancer, constitute cancers occurring exclusively or primarily, respectively, in women. Thus, a tracer designed not only for one but multiple malignancies has theoretic attractions.

FAPI PET: Fibroblast Activation Protein Inhibitor Use in Oncologic and Nononcologic Disease.

Gallium 68 (Ga)-labeled fibroblast activation protein (FAP) inhibitor (FAPI) PET is based on the molecular targeting of the FAP, which is known to be highly expressed in the major cell population in tumor stroma, termed cancer-associated fibroblasts. Among many FAP-targeted radiopharmaceuticals developed so far, Ga-FAPI exhibits rapid tracer accumulation in target lesions and low background signal, which results in excellent imaging features. FAPI PET can be integrated in the clinical workflow and enables the detection of small primary or metastatic lesions, especially in the brain, liver, pancreas, and gastrointestinal tract due to the low tracer accumulation in these organs.

Three-Time-Point PET Analysis of Ga-FAPI-46 in a Variety of Cancers.

A growing family of Ga-fibroblast activation protein inhibitor (FAPI) PET probes has shown promise in imaging a variety of medical conditions. Ga-FAPI-46, in particular, has emerged as unique for both its diagnostic and its theranostic applications; however, the optimal timing of PET remains unclear. Therefore, we evaluated uptake at 3 time points after Ga-FAPI-46 administration in a spectrum of tumor types.

Advancement and Future Perspective of FAPI PET/CT In Gynecological Malignancies.

Fibroblast activation protein (FAP) is ubiquitously present in healthy tissue, and additionally upregulated by cancer associated fibroblasts (CAFs) leading to high levels of FAP. Thus, neoplastic tissue, which is containing CAFs, characterized by a high presence of FAP. Moreover, in more than 90% of all epithelial tumors this phenomenon seems to occur, including many gynecological tumors, providing the foundation for a successful application of FAP-ligands.

Repetitive Early Ga-FAPI PET Acquisition Comparing Ga-FAPI-02, Ga-FAPI-46, and Ga-FAPI-74: Methodologic and Diagnostic Implications for Malignant, Inflammatory/Reactive, and Degenerative Lesions.

Ga-labeled fibroblast activation protein (FAP) inhibitor (Ga-FAPI) PET targets Ga-FAPI-positive activated fibroblasts and is a promising imaging technique for various types of cancer and nonmalignant pathologies. However, discrimination between malignant and nonmalignant Ga-FAPI-positive lesions based on static PET with a single acquisition time point can be challenging. Additionally, the optimal imaging time point for Ga-FAPI PET has not been identified yet, and different Ga-FAPI tracer variants are currently used.

[ Ga]Ga-FAPI uptake correlates with the state of chronic kidney disease.

Purpose: Kidney fibrosis leads to a progressive reduction in kidney function ultimately resulting in kidney failure. Diagnostic tools to detect kidney fibrosis are all invasive in nature requiring kidney biopsies with subsequent histological validation. In this retrospective study, the diagnostic value of three different radiotracers for the noninvasive prediction of kidney fibrosis was analyzed, taking into account the glomerular filtration rate (GFR) and the intra-renal parenchymal radiotracer uptake.

FAP and FAPI-PET/CT in Malignant and Non-Malignant Diseases: A Perfect Symbiosis?

A fibroblast activation protein (FAP) is an atypical type II transmembrane serine protease with both endopeptidase and post-proline dipeptidyl peptidase activity. FAP is overexpressed in cancer-associated fibroblasts (CAFs), which are found in most epithelial tumors. CAFs have been implicated in promoting tumor cell invasion, angiogenesis and growth and their presence correlates with a poor prognosis.

Positive Multifocal PSMA PET/CT in a Patient With Prostate Cancer and Follicular Lymphoma.

Prostate-specific membrane antigen (PSMA) PET/CT is a highly reliable nuclear tracer for diagnostic imaging of prostate cancer. However, PSMA is also expressed by some nonprostatic tissues such as benign tumors, inflammatory processes, and malignant neoplasms. This case presents a patient with prostate cancer and follicular lymphoma undergoing PSMA PET/CT.

High fibroblast-activation-protein expression in castration-resistant prostate cancer supports the use of FAPI-molecular theranostics.

Purpose: To evaluate fibroblast-activation-protein (FAP) expression in different clinical stages of prostate cancer (PC) with regards to utility of [ Ga]Ga-FAPI-04 PET/CT imaging in patients with castration-resistant PC (CRPC).

Methods: Tissue microarrays (TMAs) were constructed from prostatic tissue from 94 patients at different stages of PC (primary PC, patients undergoing neoadjuvant androgen deprivation therapy, CRPC, and neuroendocrine PC (NEPC)) and were stained with anti-FAP monoclonal antibody. A positive pixel count algorithm (H-Index) was used to compare FAP expression between the groups.

Head-to-head intra-individual comparison of biodistribution and tumor uptake of Ga-FAPI and F-FDG PET/CT in cancer patients.

Purpose: FAPI ligands (fibroblast activation protein inhibitor), a novel class of radiotracers for PET/CT imaging, demonstrated in previous studies rapid and high tumor uptake. The purpose of this study is the head-to-head intra-individual comparison of Ga-FAPI versus standard-of-care F-FDG in PET/CT in organ biodistribution and tumor uptake in patients with various cancers.

Material And Methods: This international retrospective multicenter analysis included PET/CT data from 71 patients from 6 centers who underwent both Ga-FAPI and F-FDG PET/CT within a median time interval of 10 days (range 1-89 days).

The Role of Fibroblast Activation Protein Ligands in Oncologic PET Imaging.

Fibroblast activation protein inhibitor emerges as a novel and highly promising agent for diagnostic and possibly theranostic application in various malignant and non-malignant diseases. FAPI impresses with its selective expression in several pathologies, ligand induced internalization, and presence in a large variety of malignancies. Current studies indicate that FAPI is equal or even superior to the current standard oncological tracer fluorodeoxyglucose in several oncological diseases.

Ga-FAPI-PET/CT in patients with various gynecological malignancies.

Purpose: Ga-FAPI (fibroblast activation protein inhibitor) is a novel and highly promising radiotracer for PET/CT imaging. The aim of this retrospective analysis is to explore the potential of FAPI-PET/CT in gynecological malignancies. We assessed biodistribution, tumor uptake, and the influence of pre- or postmenopausal status on tracer accumulation in hormone-sensitive organs.