Comparative Immunohistochemical Analysis of FAP and c-MET Expression Across Renal Cell Carcinoma Subtypes: Preliminary Results and Potential Theranostic Implications.
- 1Department of Nuclear Medicine, LMU University Hospital, LMU Munich, 91377 Munich, Germany.
- 2Institute of Pathology, Faculty of Medicine, LMU Munich, 80337 Munich, Germany.
- 3Department of Urology, LMU University Hospital, LMU Munich, 81377 Munich, Germany.
Abstract
Background: Renal cell carcinoma (RCC) comprises multiple histopathological subtypes with distinct biological characteristics and clinical behavior. Despite advances in conventional imaging, the detection of small RCC lesions or distant metastases remains challenging and the prognosis of advanced RCC is still poor. Theranostic approaches are promising tools combining diagnostic imaging and targeted radionuclide-based cancer therapy. The identification of suitable molecular targets in tumor tissue is a major focus of current research. Fibroblast activation protein (FAP) and hepatocyte growth factor receptor (c-MET) have been proposed as theranostic targets in several solid cancers, including RCC. However, available data are limited and inconsistent, particularly regarding expression patterns across different RCC subtypes. Methods: In this study, we evaluated the expression patterns of FAP and c-MET immunohistochemically across major RCC subtypes (clear cell RCC [ccRCC], papillary RCC [pRCC], and chromophobe RCC [cpRCC]). Staining intensity was assessed semi-quantitatively and correlated with histological RCC subtypes. Results: FAP expression differed substantially among RCC subtypes, being highest in ccRCC, significantly lower in pRCC, and largely absent in cpRCC. In contrast, c-MET was ubiquitously expressed across all three RCC subtypes but showed a lower specificity for tumor cells. Conclusions: Our results provide a rationale for further evaluating FAP and c-MET as potential theranostic targets across RCC subtypes and establishing a foundation for future RCC-subtype-specific imaging-pathology correlation studies. Validation in larger multicenter cohorts including paired molecular imaging data is required before their clinical translation can be considered.
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BibTeX
@article{unterrainer2026comparative,
title = {{Comparative Immunohistochemical Analysis of FAP and c-MET Expression Across Renal Cell Carcinoma Subtypes: Preliminary Results and Potential Theranostic Implications.}},
author = {Lena M Unterrainer and Adrien Holzgreve and Sophie C Siegmund and Magdalena Schöll and Julia Schwenke and Rudolf A Werner and Frederick Klauschen and Michael Staehler and Stephan T Ledderose},
journal = {Diagnostics (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/diagnostics16193228},
url = {https://europepmc.org/article/MED/42882383},
note = {CC BY},
}
RIS
TY - JOUR
TI - Comparative Immunohistochemical Analysis of FAP and c-MET Expression Across Renal Cell Carcinoma Subtypes: Preliminary Results and Potential Theranostic Implications.
AU - Lena M Unterrainer
AU - Adrien Holzgreve
AU - Sophie C Siegmund
AU - Magdalena Schöll
AU - Julia Schwenke
AU - Rudolf A Werner
AU - Frederick Klauschen
AU - Michael Staehler
AU - Stephan T Ledderose
PY - 2026
DA - 2026/10/06
JO - Diagnostics (Basel, Switzerland)
DO - 10.3390/diagnostics16193228
UR - https://europepmc.org/article/MED/42882383
AB - Background: Renal cell carcinoma (RCC) comprises multiple histopathological subtypes with distinct biological characteristics and clinical behavior. Despite advances in conventional imaging, the detection of small RCC lesions or distant metastases remains challenging and the prognosis of advanced RCC is still poor. Theranostic approaches are promising tools combining diagnostic imaging and targeted radionuclide-based cancer therapy. The identification of suitable molecular targets in tumor tissue is a major focus of current research. Fibroblast activation protein (FAP) and hepatocyte growth factor receptor (c-MET) have been proposed as theranostic targets in several solid cancers, including RCC. However, available data are limited and inconsistent, particularly regarding expression patterns across different RCC subtypes. Methods: In this study, we evaluated the expression patterns of FAP and c-MET immunohistochemically across major RCC subtypes (clear cell RCC [ccRCC], papillary RCC [pRCC], and chromophobe RCC [cpRCC]). Staining intensity was assessed semi-quantitatively and correlated with histological RCC subtypes. Results: FAP expression differed substantially among RCC subtypes, being highest in ccRCC, significantly lower in pRCC, and largely absent in cpRCC. In contrast, c-MET was ubiquitously expressed across all three RCC subtypes but showed a lower specificity for tumor cells. Conclusions: Our results provide a rationale for further evaluating FAP and c-MET as potential theranostic targets across RCC subtypes and establishing a foundation for future RCC-subtype-specific imaging-pathology correlation studies. Validation in larger multicenter cohorts including paired molecular imaging data is required before their clinical translation can be considered.
SN - 2075-4418
ER -