Anti-angiogenic agents in ovarian cancer: dawn of a new era?

Epithelial ovarian cancer is a leading cause of cancer-related death for women both in the United States and worldwide, and the effectiveness of cytotoxic chemotherapy has plateaued. Angiogenesis plays an important role in ovarian cancer biology, and exploration of anti-angiogenic agents in this disease has demonstrated anti-tumor activity both as monotherapy and in combination with cytotoxic chemotherapy. However, key questions remain regarding the use of these drugs in ovarian cancer, such as where in treatment should they be used, should these drugs be used as single agents or combined with chemotherapy, can and which biomarkers predict efficacy, are there efficacy and toxicity differences amongst the various agents, what are the cost-benefit ratios of these therapies, and are the patient outcome improvements observed in completed studies significant enough to warrant widespread use of these drugs? Here, we review recent progress and discuss ongoing controversies regarding the use of anti-angiogenic therapies in ovarian cancer.

Independent prognostic relevance of microvessel density in advanced epithelial ovarian cancer and associations between CD31, CD105, p53 status, and angiogenic marker expression: A Gynecologic Oncology Group study

OBJECTIVES

The aims of this study were to examine prognostic significance of microvessel density (MVD) in previously-untreated, advanced epithelial ovarian cancer (EOC) and explore associations between MVD and factors that affect angiogenesis.

METHODS

MVD was determined by immunohistochemical expression of CD31 or CD105 in tumor sections from 106 women treated on GOG randomized phase III trials. Average MVD hotspots were quantified by light microscopy at high power (x400) and categorized as low (<upper quartile) or high (>or=upper quartile). Immunoblot expression of MASPIN, THBS-1, bFGF, VEGF, VEGFR-1 and p53 status (mutation and overexpression) was previously determined.

RESULTS

Of 106 evaluable cases, 25% exhibited high CD31-MVD (>24.25 vessels/high power field [HPF]) or high CD105-MVD (>19.25 vessels/HPF). After adjusting for age and stratifying by GOG performance status, stage, cell type, grade, debulking status and treatment regimen, high versus low CD105-MVD was associated with increased risk of disease progression (hazard ratio [HR]=1.873; 95% confidence interval [CI]: 1.102-3.184; p=0.020), but not death (HR=1.125; 95% CI: 0.654-1.935; p=0.670) whereas CD31-MVD was not associated with risk of disease progression (HR=1.578; 95% CI=0.918-2.711; p=0.099) or death (HR=1.678; 95% CI=0.957-2.943; p=0.071). CD31-MVD was correlated with CD105-MVD (p=0.001) and MASPIN (p=0.016). Neither CD31-MVD nor CD105-MVD was associated with p53 status, THBS-1, bFGF, VEGF or VEGFR-1.

CONCLUSIONS

High MVD assessed using CD105, a marker of proliferating endothelial cells and neoangiogenesis, but not CD31 a pan-endothelial marker, appeared to be an independent prognostic factor for worse progression-free survival in women with advanced EOC after adjusting for prognostic clinical covariates.