Treatment with cetuximab, a monoclonal antibody directed against the epidermal growth factor receptor, improves overall and progression-free survival.
In addition, cetuximab preserves the quality of life in patients with colorectal cancer that has not responded to chemotherapy.
The mutation status of the K-ras gene in the tumor may affect the response to cetuximab, and have treatment-independent prognostic value.
Dr Christos Karapetis and colleagues from Australia analyzed tumor samples, obtained from 394 of 572 patients with colorectal cancer, who were randomly assigned to receive cetuximab plus best supportive care or best supportive care alone.
The researchers searched for activating mutations in exon 2 of the K-ras gene.
|42% had at least 1 mutation in exon 2 of the gene|
|New England Journal of Medicine|
The team assessed whether the mutation status of the K-ras gene was associated with survival in the cetuximab and supportive-care groups.
The researchers found that of the tumors evaluated for K-ras mutations, 42% had at least 1 mutation in exon 2 of the gene.
The effectiveness of cetuximab was significantly associated with K-ras mutation status.
The team found in patients with wild-type K-ras tumors, treatment with cetuximab as compared with supportive care alone improved overall survival and progression-free survival.
The research team found that among patients with mutated K-ras tumors, there was no difference between those who were treated with cetuximab and those who received supportive care alone with respect to overall survival or progression-free survival.
In the group of patients receiving best supportive care alone, the mutation status of the K-ras gene was not significantly associated with overall survival.
Dr Karapetis’ team concluded, “Patients with a colorectal tumor bearing mutated K-ras did not benefit from cetuximab, whereas patients with a tumor bearing wild-type K-ras did benefit from cetuximab.”
“The mutation status of the K-ras gene had no influence on survival among patients treated with best supportive care alone.”