According to the results of a Phase III clinical trial, the addition of the targeted therapy Avastin® (bevacizumab) to post-surgery chemotherapy does not reduce the risk of cancer recurrence among patients with early-stage colon cancer. These results were made available in a press release from Roche.

Targeted therapies are anticancer drugs that interfere with specific pathways involved in cancer cell growth or survival. Some targeted therapies block growth signals from reaching cancer cells; others reduce the blood supply to cancer cells; and still others stimulate the immune system to recognize and attack the cancer cell. Depending on the specific “target,” targeted therapies may slow cancer cell growth or increase cancer cell death. Targeted therapies may be used in combination with other cancer treatments such as conventional chemotherapy. Recently approved targeted therapies represent the most novel advance in the treatment of metastatic colorectal cancer in the last few years.

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.

Multiple studies have shown that the addition of Avastin to standard chemotherapy improves outcomes in the treatment of patients with metastatic colorectal cancer. Given these results, researchers have also initiated studies to evaluate Avastin in the adjuvant (post-surgery) treatment of patients with earlier-stage colon cancer.

The current results are from a Phase III trial known as NSABP C-08. The study enrolled patients with Stage II or Stage III colon cancer. After surgical removal of the cancer, patients were assigned to receive adjuvant chemotherapy alone (mFOLFOX6) or adjuvant chemotherapy plus Avastin.

The results of the study indicate that the addition of Avastin to chemotherapy did not reduce the risk of cancer recurrence. Full results from this study are expected to be presented at the annual meeting of the American Society of Clinical Oncology (ASCO), which will be held May 29-June 2, 2009.

Results from another Phase III trial of Avastin in early-stage colon cancer (the AVANT study) are expected to be available in 2010.

The results of these studies do not affect the use of Avastin in advanced colon cancer. 

Reference: Roche Media Release. Phase III C-08 study of Avastin in early-stage colon cancer does not meet primary endpoint. Available at: Accessed April 22, 2009.

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