Can the addition of targeted drugs to chemotherapy improve response rates in advanced colorectal cancer?

The authors aimed to evaluate the addition of bevacizumab (Avastin) or cetuximab (Erbitux) to chemotherapy in advanced colorectal cancer.

Previously, the therapeutic options for patients who failed chemotherapy for advanced colorectal cancer have been limited. However, during the last few years, new targeted therapies have been developed. These therapies target proteins involved in cancer development such as epidermal growth factor receptors (EGFR; causes increased cell division when present in abnormally high amounts) and vascular endothelial growth factor (VEGF; stimulates new blood vessel formation to supply the tumor). These proteins can be inhibited using drugs such as bevacizumab (targets VEGF) or cetuximab (targets EGFR).

The authors aimed to identify whether the addition of bevacizumab or cetuximab to chemotherapy regimens could improve response rates in advanced colorectal cancer. The authors analysed 9 clinical trials with a total of 3,790 patients with advanced colorectal cancer.

Overall, treatment with bevacizumab or cetuximab plus chemotherapy was associated the complete disappearance of all signs of cancer (a complete response) in 2.4% of patients compared to 1.3% in patients receiving chemotherapy plus placebo (a substance that has no therapeutic effect). Specifically, treatment with bevacizumab plus chemotherapy was associated with the complete disappearance of all signs of cancer in 3.1% of patients compared to 0.8% for cetuximab plus chemotherapy. 

The authors concluded that their study supported the combination of either bevacizumab or cetuximab with chemotherapy in advanced colorectal cancer.

All studies had enrolled patients with adequate organ function and no severe co-existing diseases, which may not represent the normal population of colorectal cancer patients.