Patients with colon cancer have learned over the last two years that we have now a genetic marker which can predict efficacy of antibodies against EGFR which are used in patients with metastatic colon cancer.
We have learned that tumors with mutations in KRAS will not benefit from this treatment. All patients should be tested for KRAS mutation if they have advanced or metastatic disease.
However patients who have mutations of the KRAS gene don’t do worse than patients with wild type. The only difference is that the drugs which target EGFR will not work.
We really have had no marker which identifies patients who have a tumor which is very aggressive and grows independently of whatever treatment we initiate. Recent data suggest we may have identified a marker like this. The marker is called BRAF.
Only about 5 percent of patients with metastatic disease carry a mutation in this gene. Preliminary studies suggest that patients with tumors harboring this mutation do much worse. However more studies are needed to validate these findings.
The reason I am sharing this with you is because we have now therapies available which may inhibit this particular mutation. BRAF mutations are common in melanomas and bile duct cancers, and recent developments show that we may have very powerful inhibitors for patients with this mutation.
In our practice we are screening for these mutations since we have a number of clinical trials allowing patients to be tested with a BRAF inhibitor.
Please discuss these options with your oncologist if your first line therapy is not working to see if you are eligible for clinical trials when you have either a mutant KRAS or mutant BRAF gene in your tumor.