Article
Expression and therapeutic potential of TROP-2 in Cisplatin-resistant non-seminomatous germ cell tumors
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Published: | April 2, 2025 |
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Background: Cisplatin-based chemotherapy has been the standard of care for metastatic germ cell tumors (mGCT) for the past four decades due to its high efficacy. However, cisplatin-refractory patients have a poor prognosis due to limited treatment options. Therefore, there is an unmet need for effective therapies for these patients, such as antibody-drug conjugates (ADCs), which have shown significant clinical efficacy in metastatic solid tumors. Our objective was to evaluate the expression of TROP-2 in cisplatin-resistant non-seminomatous GCT (NSGCT) metastases [MET(-R)] and to assess the cytotoxic efficacy of the anti-TROP-2 ADC Sacituzumab govitecan (SG) in NSGCT cell lines.
Methods: TROP-2 mRNA and protein levels were measured using qRT-PCR and immunohistochemistry with H-score evaluation in MET(-R), including embryonal carcinoma (EC), choriocarcinoma (CC), yolk sac tumor (YST) and teratoma (TER). In vitro analyses included Western Blot and cell viability assay were performed in GCT cell lines, including cisplatin-resistant subclones (-R) derived from EC (NCCIT, 2102EP), CC (JAR, JEG-3, BeWo), and an EC-YST-intermediate (1411H), to assess the cytotoxic efficacy of the anti-TROP-2 ADC SG.
Results: We demonstrated that TROP-2 mRNA levels were significantly increased in CC and TER-MET(-R) compared to EC and YST-MET(-R) (p<0.01). Immunohistochemical staining revealed moderate to strong membranous TROP-2 expression in 100% of CC-MET(-R) [n=4/4, with H-score ≥ 100, median H-score 250 (IQR 187.5–290)] and in 88.9% of TER-MET(-R) cases [median H-score 255 (IQR 200–265)], while TROP-2 was absent or weak in patients with EC [median H-score 22.5 (IQR 5–73.75)], and YST [median H-score 0 (IQR 0–12.5)] cases (p<0.01). In vitro analyses indicated that the efficacy of SG depended on the extent of TROP-2 expression (p<0.01).
Conclusion: In summary, we identified TROP-2 as a potential therapeutic target for a subset of patients with cisplatin-refractory NSGCT and highlighted the potential benefit of TROP-2-directed ADCs, such as SG, for TROP-2-positive mGCT patients.