UPDATE 2-Gene predicts Erbitux success in colon cancer
(Adds comments, background, byline; dateline previously NEW YORK)
By Debra Sherman
CHICAGO, June 1 (Reuters) - A type of gene present in tumors can help predict whether patients with newly diagnosed advanced colon cancer will benefit from treatment with ImClone Systems Inc's IMCL.O Erbitux, according to data presented on Sunday.
The findings bring researchers another step closer to the "Holy Grail" of so-called personalized medicine, whereby information about a patient's genotype is used to select medication.
The study, looking at a subset of subjects from a larger clinical trial, found that colon cancer patients whose tumors contained the normal, or wild type, KRAS gene could gain a significant benefit from Erbitux treatment, while those with a mutated KRAS gene saw no benefit from the ImClone drug.
The results, presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago, demonstrate that a genetic test could help rule out roughly one-third of patients whose cancer would not be helped by the expensive biotechnology drug, as well as identify those most likely to benefit.
"These drugs are not cheap so if they're not going to help, we won't use them," said Dr. Eric Van Cutsem of the University Hospital Gasthuisberg in Belgium, who led the research.
Among patients with normal KRAS, 59.3 percent had their tumors shrink by more than half after receiving Erbitux and chemotherapy, compared to 43.2 percent on chemotherapy alone.
The results were deemed to be statistically significant, researchers said. Erbitux made no difference in patients with a mutated KRAS gene.
European medical experts had backed Erbitux as first-line use in metastatic colorectal cancer patients with a certain genetic profile.
The recommendation is specifically for people with the wild-type KRAS gene and who account for up to 65 percent of metastatic colorectal cancer patients.
Van Cutsem said there were no signs of toxicity and side effects were manageable.
Erbitux belongs to a new wave of targeted cancer therapies and competes with Avastin from Genentech Inc DNA.N and Roche Holding AG (ROG.VX).
Erbitux is an antibody designed to block a protein called epidermal growth factor, which is believed to play a role in cancer cell growth. Avastin is an antibody that works by cutting off blood supply to tumors.
KRAS is a gene that codes for a protein involved in the epidermal growth factor pathway. In non-mutated or wild-type tumors, the KRAS protein is tightly regulated, allowing Erbitux to work effectively. In mutant tumors, however, the KRAS protein is permanently "turned on", and experts think this may make treatment less efficient.
Dr. Julie Gralow, of the University of Washington, said these KRAS findings represent "a giant step" in tailoring treatment.
"We've struggled with this for years," said Gralow, who specializes in breast cancer.
She said there are hundreds of so-called targeted therapies in the pipelines.
"Save the money and save the toxicity" if those patients won't be helped by a certain drug. "That's how we'll be able to afford these targeted drugs," Gralow said.
However, it is unclear yet whether the KRAS findings can be applied to other types of cancer. "You can bet we're going to be looking at it," Gralow said.
