Antibody-drug conjugates as a novel therapeutic modality to treat recurrent refractory germ cell tumors.

This review provides a rationale for using the Food and Drug Administration (FDA)-approved antibody-drug conjugates (ADCs) for implementing as therapy in recurrent refractory germ cell tumors similar to their position in the treatment of other types of chemoresistant solid tumors. Germ cell tumors (GCTs) originate from germ cells; they most frequently develop in ovaries or in the testes, while being the most common type of malignancy in young men. GCTs are very sensitive to cisplatin-based chemotherapy, but therapeutic resistance occurs in a considerable number of cases, which is associated with disease recurrence and poor patient prognosis. ADCs are a novel type of targeted antitumor agents that combine tumor antigen-specific monoclonal antibodies with chemically linked chemotherapeutic drugs (payload) exerting a cytotoxic effect. Several FDA-approved ADCs use as targeting moieties the antigens that are also detected in the GCTs, offering a benefit of this type of targeted therapy even for patients with relapsed/refractory testicular GCTs (rrTGCT) unresponsive to standard chemotherapy.

Association between glutathione S-transferases M1 expression and treatment outcome in germ cell tumor patients.

Cisplatin-based chemotherapy is the mainstay in the treatment of germ cell tumors (GCTs). Glutathione S-transferases (GSTs) are polymorphic enzymes that catalyze the glutathione conjugation of alkylating agents, platinum compounds, and free radicals formed by chemotherapy and are thus implicated in developing treatment resistance. This study aimed to assess the expression level of GST mu 1 (GSTM1) and its association with treatment outcomes in patients with GCT. This translational study included tumor specimens from 207 patients with newly diagnosed GCTs, as well as cisplatin-sensitive GCT cell line xenografts and their resistant variants for all histological variants of GCTs. GSTM1 expression was detected by reverse transcription-quantitative PCR and immunohistochemistry using monoclonal antibodies, scored by the multiplicative quickscore (QS) method. GSTM1 expression was correlated with patient/tumor characteristics and treatment outcomes. The highest GSTM1 expression was observed in seminoma, followed by choriocarcinoma, embryonal carcinoma, and yolk sac tumor, while the lowest was observed in teratoma (p<0.0001). There was no association between GSTM1 expression in tumor tissue and patient/tumor characteristics. The low GSTM1 expression was associated with significantly better relapse-free survival compared with high GSTM1 (HR=0.50, 95% CI 0.23-1.09, p=0.03) but not overall survival (HR=0.61, 95% CI 0.24-1.54, p=0.22). Multivariate analysis showed that the prognostic value of GSTM1 was independent of the International Germ Cell Cancer Collaborative Group (IGCCCG) score. These data revealed the prognostic value of GSTM1 in GCTs, with a high GSTM1 expression associated with worse outcomes, suggesting that GSTM1 could be responsible, in part, for treatment resistance in GCTs.