Improved survival rates have been observed in castration-resistant prostate cancer (CRPC) due to advancements in treatment options. However, individuals with brain metastases still have limited therapeutic options and an unfavorable prognosis. Therefore, there is an urgent need to explore new therapeutic avenues, such as antibody-drug conjugates (ADCs), which have demonstrated significant clinical activity against active brain metastases in solid tumors. Our objective was to determine the expression levels of the ADC targets Trop-2 and NECTIN-4 in cerebral metastasized CRPC (mCRPC).
Immunohistochemical staining of Trop-2 and NECTIN-4 with evaluation of H-score was performed in CRPC brain metastases (n = 31). Additionally, we examined Trop-2 protein expression in prostate cancer cell lines and studied their responsiveness to the anti-Trop-2 ADC Sacituzumab govitecan (SG) in vitro.
Our analysis revealed that most patients exhibited moderate to strong Trop-2 expression [n = 27/31 with H-score ≥100, median H-score 220 (IQR 180-280)], while NECTIN-4 was absent in all cerebral metastases. Mechanistically, we demonstrated that the efficacy of SG depends on Trop-2 expression levels in vitro. Overexpression of Trop-2 in Trop-2-negative PC-3 cells led to sensitization to SG, whereas CRISPR-Cas9-mediated knockdown of Trop-2 in Trop-2-expressing DU-145 cells conferred resistance to SG.
The substantial expression of Trop-2 in cerebral metastases, along with our preclinical in vitro results, supports the efficacy of SG in treating cerebral mCRPC. Thus, our results extend the understanding of the potential of ADCs in prostate cancer treatment and provide an additional treatment strategy for the challenging subset of patients with cerebral metastases.
Cancer medicine. 2024 Jun [Epub]
Richard Weiten, Max Niemann, Eduard Below, Lea L Friker, Damian J Ralser, Marieta Toma, Glen Kristiansen, Oliver Hahn, Sabrina Zechel, Viktor Grünwald, Tobias Bald, Johannes Siewert, Torsten Pietsch, Manuel Ritter, Michael Hölzel, Markus Eckstein, Abdullah Alajati, Philipp Krausewitz, Niklas Klümper
Department of Urology and Paediatric Urology, University Hospital Bonn, Bonn, Germany., Institute of Experimental Oncology, University Hospital Bonn, Bonn, Germany., Institute of Pathology, University Hospital Bonn, Bonn, Germany., Department of Urology, University Hospital Göttingen, Göttingen, Germany., Institute of Neuropathology, University Hospital Göttingen, Göttingen, Germany., Clinic for Internal Medicine (Tumor Research) and Clinic for Urology, Interdisciplinary Genitourinary Oncology at the West-German Cancer Center, University Hospital Essen, Essen, Germany., Institute of Neuropathology, University Hospital Bonn, Bonn, Germany., Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.