Your genes may determine how you respond to cancer-fighting drugs.
It’s long been known that certain patients with advanced colorectal cancer did not respond to drug therapies when they had a certain gene mutation. Scientists have now uncovered a second gene mutation that determines whether or not a patient will respond to the colon cancer drugs, Erbirtux and Vectibix.
Targeting cancer therapies based on your genetic make-up is the new horizon in research, according to experts meeting in Geneva today.
In the case of Erbitux, developed by ImClone, and Vectibix from Amgen, experts knew that the drugs worked in tumors with the normal or wild-type version of the K-ras gene. Among the patients who fail to respond to the drug, 30-40 percent have a K-ras mutation.
A study released in the New England Journal of Medicine released yesterday, confirmed earlier results showing that Erbitux doesn't help patients with a mutation in the K-ras gene.
Now a second gene, BRAF, may also be involved, researchers find.
The BRAF mutation may account for another 12 percent of patients who fail to respond.
Researchers from the University Of Turin School Of Medicine in Italy are presenting their results. More study is needed as more than half of patients in the Italian study who failed to respond to treatment did not have the gene mutation in either gene.
Colorectal tumors are the second most common cause of cancer death in the U.S.
This latest research echoes a study presented this spring at the American Society of Clinical Oncology on 600 patients. About two-thirds of colon cancer patients who did not have the mutated gene K-ras were the better candidates for Erbitux.
Erbitux (Cetuximab), is most effective in colon cancer patients. Among the 36 percent of patients who will not see an improvement with Erbitux, they will be treated instead with Avastin, made by Genentech and Roche.
The future of targeted treatments may be to use genetic markets to pre-select patients for treatment. #