Angiogenesis biomarkers in ovarian cancer

Abstract

Epithelial ovarian cancer (EOC) is relatively common. Most patients present with advanced disease and although initial response to chemotherapy is often good, the majority of patients will experience relapse. Relapsed EOC becomes progressively more drug resistant, meaning that more effective therapies are needed to improve quality of life and prolong survival. One such approach is the use of molecularly-targeted agents, many of which are being evaluated in ovarian cancer. The mechanism of action of a number of targeted agents is to interfere with the process of angiogenesis, but despite much research, none have yet been validated for patient selection and monitoring response in any tumor type. The search for candidate plasma- and tissue-based biomarkers for anti-angiogenesis therapy in ovarian cancer has largely focussed on vascular endothelial growth factor (VEGF), although micro-vessel density and others have been proposed and evaluated. Gene expression profiling is another approach to identifying biomarkers, and recent results suggest that this may be useful for predicting the response to bevacizumab. Other genetic and molecular biomarkers are being investigated, with some showing the potential to identify patients who will benefit from anti-VEGF therapy. Identification of biomarkers is now included as part of large, randomized, placebo-controlled, phase III trials, although the number of variables to be taken into account, the requirement to have reliable and specific biomarkers for each therapeutic agent (or class of agents), and the fact that biomarkers probably vary by treatment settings (e.g. neo-adjuvant, adjuvant) makes biomarker identification challenging.