TAMPA – Malignant ascites independently predicts poor prognosis among women with newly diagnosed advanced ovarian cancer, and thus may predict the likelihood of deriving long-term benefit from bevacizumab treatment, an investigator reported at the annual meeting of the Society of Gynecologic Oncology.
Of 1,151 completely resected patients with advanced epithelial ovarian cancer who were included in the Gynecologic Oncology Group (GOG) 218 study comparing standard cytotoxic chemotherapy with and without bevacizumab, 914 (79%) had ascites, and those patients were more likely than patients without ascites to have poor performance status, high-grade serous histology, higher baseline CA 125, and suboptimal cytoreduction, Dr. James Stuart Ferriss of Temple University, Philadelphia, reported.
Dr. James Stuart Ferriss
However, according to a post hoc analysis of data from the randomized, placebo-controlled, double-blinded study, ascitic patients treated with concurrent and maintenance bevacizumab had significantly better overall survival (hazard ratio, 0.82) and improved progression-free survival (HR, 0.72), compared with those who did not receive bevacizumab, Dr. Ferriss said.
The presence of ascites in this study was defined prospectively as more than 50 cm3 of peritoneal fluid at the time of maximum surgical cytoreductive effort. The two treatment arms were balanced with respect to the presence of ascites and other prognostic factors, he said.
For patients without ascites, no difference was seen in progression-free survival or overall survival based on treatment arm.
This secondary analysis was undertaken because bevacizumab was shown in GOG 218 and other studies to improve progression-free survival, but not overall survival, when given with cytotoxic chemotherapy and for maintenance therapy in patients with epithelial ovarian, fallopian tube, and peritoneal cancers, but factors predictive of long-term efficacy have remained elusive.
In fact, vascular endothelial growth factor inhibition (anti-VEGF) therapy as a whole has demonstrated "mostly short-term clinical benefit," he said.
A notable exception is cediranib, which demonstrated overall survival benefit in the ICON6 trial, he noted.
Because of limitations inherent in an unplanned analysis, the findings should be considered hypothesis generating, but if confirmed, they may change the application of bevacizumab in front-line therapy, he said.
Since malignant ascites has been associated with VEGF expression, thus providing a biological rationale that targeting VEGF could have preferential benefit for patients whose cancers are producing ascites, he and his colleagues investigated the value of ascites as a predictor of efficacy for bevacizumab.
Dr. Ferriss reported having no disclosures.