Bevacizumab in the therapy for refractory metastatic colorectal cancer

Colorectal cancer is the second most common cause of cancer related deaths in the United States. Recent developments have led to prolonged survival with the use of sequential lines of chemotherapy agents. The addition of bevacizumab to active chemotherapy has further improved survival when used in the first and second lines of therapy for metastatic colorectal cancer. Evidence supporting the continued use of bevacizumab throughout lines of therapy is accumulating. Clinical trials are underway in which bevacizumab is continued beyond the first line of a chemotherapy and bevacizumab combination regimen. The mechanism by which colorectal cancer may become resistant to bevacizumab is poorly understood. Molecular and biochemical correlates which may identify bevacizumab resistance are an important component in the design of these clinical trials.