FAP Expression in Renal Tumors Assessed by [<sup>68</sup>Ga]Ga-FAPI-46 PET Imaging and FAP Immunohistochemistry: A Case Series of Six Patients from the Prospective Exploratory Trial NCT04147494.
case_series · Level IV
Where this comes from
- Record sourced from PubMed, PMID 41101974.
- Also identified by DOI 10.2967/jnumed.125.270346 and PMC identifier 12766859.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Fibroblast activation protein (FAP) has been proposed as a pan-tumor target for PET imaging using FAP-targeted tracers. Here, we explore the potential value of FAP PET in renal tumors. <b>Methods:</b> Six patients with renal tumors (4 with clear cell renal cell carcinoma, 1 with papillary renal cell carcinoma, and 1 with renal oncocytoma) who were included in a prospective imaging study (NCT04147494) underwent [<sup>68</sup>Ga]Ga-FAPI-46 PET before nephrectomy. FAP PET radiotracer uptake and FAP expression by immunohistochemistry were assessed in the tumors and surrounding renal parenchyma. <b>Results:</b> Tumoral FAP radiotracer uptake was highest in clear cell renal cell carcinoma (median SUV<sub>max</sub>, 3.1; range, 2.5-5.3), followed by renal oncocytoma (SUV<sub>max</sub>, 1.9) and papillary renal cell carcinoma (SUV<sub>max</sub>, 1.1). The FAP PET signal strongly correlated with FAP expression by immunohistochemistry (SUV<sub>max</sub>; <i>r</i> = 0.93; <i>P</i> = 0.007). <b>Conclusion:</b> FAP expression in different renal tumors, including renal cell carcinoma, was lower when compared with cancers with known FAP expression, such as sarcoma. Although our data do not favor FAP-based theranostic approaches in renal cell carcinoma, studies in larger cohorts are warranted for conclusive evidence.
Medical subject headings
- Gelatinases
- Gene Expression Regulation, Neoplastic
- Kidney Neoplasms
- Membrane Proteins
- Positron-Emission Tomography
- Serine Endopeptidases