According to the results of two Phase III clinical trials, the addition of Avastin® (bevacizumab) to first- or second-line chemotherapy delays cancer progression but may not improve overall survival among women with advanced breast cancer. These results were presented at the 2009 San Antonio Breast Cancer Symposium (SABCS).
Avastin is a targeted therapy that blocks a protein known as VEGF. VEGF plays a key role in the development of new blood vessels. By blocking VEGF, Avastin deprives the cancer of nutrients and oxygen and inhibits its growth. Avastin’s effects on blood vessels may also improve the delivery of chemotherapy to the tumor.
A Phase III clinical trial known as AVADO evaluated the addition of Avastin to first-line chemotherapy. The study enrolled 736 patients from 24 countries. All study participants had HER2-negative locally recurrent or metastatic breast cancer. Patients were assigned to receive chemotherapy with Taxotere® (docetaxel) alone or in combination with Avastin.
As has been reported previously, the addition of Avastin to first-line chemotherapy resulted in a longer time to cancer progression than chemotherapy alone. The addition of Avastin did not, however, significantly affect overall survival.
A second study presented at SABCS (the RIBBON-2 study) evaluated the addition of Avastin to second-line chemotherapy for metastatic, HER2-negative breast cancer. Once again, Avastin delayed cancer progression. Progression-free survival was 7.2 months among patients treated with chemotherapy plus Avastin compared with 5.1 months among patients treated with chemotherapy alone. There was no significant difference in overall survival between study groups at the time of this interim analysis, but the study is ongoing.
These studies indicate that the addition of Avastin to either first- or second-line chemotherapy delays the progression of advanced HER2-negative breast cancer. There is still no clear evidence, however, that Avastin improves overall survival.
 Miles DW. Final overall Survival (OS) Results from the Randomised, Double-Blind, Placebo-Controlled, Phase III AVADO Study of Bevacizumab (BV) Plus Docetaxel (D) Compared with Placebo (PL) Plus D for the First-Line Treatment of Locally Recurrent (LR) or Metastatic Breast Cancer (mBC). Presented at the 32nd CTRC-AACR San Antonio Breast Cancer Symposium. December 9-13, 2009. San Antonio, TX. Abstract 41.
 Brufsky A. RIBBON-2: A Randomized, Double-Blind, Placebo-Controlled, Phase III Trial Evaluating The Efficacy And Safety Of Bevacizumab In Combination With Chemotherapy For Second-Line Treatment Of HER2-Negative Metastatic Breast Cancer. Presented at the 32nd CTRC-AACR San Antonio Breast Cancer Symposium. December 9-13, 2009. San Antonio, TX. Abstract 42.