Targeted or “designer” therapy for colorectal cancer patients has evolved over the last decade largely driven by better understanding of the behaviour of cancer cells and development of new drugs known as monoclonal antibodies.
Cetoximab (Erbitax) is one such agent that can be used in combination with other chemotherapy drugs resulting in improved survival rates for patients with advanced colorectal cancer. Unfortunately, not all patients with advanced disease benefit from Cetoximab, given that some may suffer disease progression after demonstrating initial good response to the drug. This is known as resistance and can occur because cancer cells have the unique ability to modify or alter their physical or chemical characteristics that otherwise would have been vulnerable to destruction by Cetoximab.
The recent findings by researchers that all patients will ultimately develop resistance to Cetoximab is ground breaking research with the following implications for patients with colorectal cancer:
- We now have a clearer understanding why some patients suffer disease progression despite earlier good response to Cetoximab
- The identification of the substitute protein ERBB2 has led to the formulation of new antagonist drugs to treat this form of resistance thereby offering the patient choice in cases where treatment options are often limited.
- A greater number of patients with advanced disease will now have the opportunity to receive potentially life-saving drugs.
I suspect that our understanding of resistance to new cancer MAB agents like Cetoximab is the turning point of a new era of more effective targeted chemotherapy agents in the battle to prolong the lives of patients with advanced colorectal cancer.
