A Phase III Gynecologic Oncology Group (GOG) clinical trial featured in a plenary session at the 46th Annual Meeting of the American Society of Clinical Oncology finds that adding bevacizumab (Avastin) to initial chemotherapy treatment - and then giving bevacizumab as maintenance therapy - significantly slows disease progression in women with advanced epithelial ovarian, primary peritoneal or fallopian tube cancer.

"This is the first time a Phase III trial has demonstrated that an anti-angiogenic agent improved progression-free survival in women with this very hard-to-treat disease," said lead researcher Robert A. Burger, M.D., director of the Women's Cancer Center at Fox Chase Cancer Center in Philadelphia, and GOG Lead Investigator. "Based on the results of this GOG trial, bevacizumab is an acceptable initial treatment option for patients with advanced ovarian, primary peritoneal and fallopian tube cancers."

Bevacizumab, which blocks the development of tumor growth-promoting blood vessels, is approved for several metastatic cancers, including those of the colon, breast, kidney, brain and lung. Previous small clinical trials showed promising activity in patients with recurrent ovarian and peritoneal cancer.

This international study included 1,873 women with newly diagnosed stage III or IV ovarian, primary peritoneal or fallopian tube cancer who had undergone surgery to remove as much of the cancer as possible. Patients were randomly assigned to one of three groups: standard chemotherapy (paclitaxel plus carboplatin) and placebo plus placebo maintenance; standard chemotherapy with bevacizumab plus placebo maintenance; or standard chemotherapy with bevacizumab, followed by bevacizumab maintenance. Maintenance therapy is defined as longer-term treatment given after standard chemotherapy, with the goal of extending cancer progression-free survival.

The researchers found that women who received standard chemotherapy plus bevacizumab followed by up to 10 months of bevacizumab maintenance had a longer period of progression free survival (median of 14.1 months) compared with those who received standard chemotherapy alone (median of 10.3 months), a difference that was statistically significant. Those who received chemotherapy and bevacizumab followed by placebo maintenance had a median progression-free survival of 11.2 months, a difference that was not statistically significant compared with those who received standard chemotherapy alone.

Although patients experienced bevacizumab-associated side effects (primarily hypertension and low white blood cell counts), the types and frequency appeared to be similar to what has been reported previously.