Biomarkers for systemic therapy in ovarian cancer.

Epithelial ovarian cancer (EOC) is the most deadly tumor of the female reproductive system. Despite improvements in understanding the biology of EOC, therapeutic strategies still depend on surgery and combination of taxane and platinum agents. Here, we provide a summary of clinically tested biomarkers potentially useful to predict drug response. Resistance against platinum derivatives can result from lower drug concentrations, alterations in the target molecule and changes in the cellular signal transduction pathways. Taxane resistance can develop due to decreased intracellular drug concentration, alterations in microtubuli structure and changes in the cellular response including ERBB2 (epidermal growth factor receptor 2). A few key genes have been suggested as biomarkers for hormonal therapy. Currently, the only targeted therapy agent approved for ovarian cancer is the VEGF (vascular endothelial growth factor) inhibitor bevacizumab. Response to bevacizumab is correlated with VEGF-A levels and hypertension. The primary problems in identifying reliable biomarkers for EOC are the usage of different clinical endpoints, multivariate analysis for a panel of clinical parameters and the lack of published comprehensive clinical information of patients enrolled in these studies. The future lies in adding targeted agents to the taxane/platinum gold standard and in a more detailed stratification of patients into sub-cohorts enabling a more effective therapy. In conclusion, a large-scale coordinated effort is needed for the robust validation of the numerous biomarker candidates available in EOC therapy.