Blood Marker Could Indicate Drug-Resistance in Colorectal Cancer

FCGR2A could indicate which patients with colorectal cancer respond to cetuximab.

In a recent study, researchers were able to identify a blood marker that determines which patients with metastatic colorectal cancer would benefit from cetuximab.

The study, published in Clinical Cancer Research, found the reasoning behind why nearly half of patients with colorectal cancer did not respond to the drug.

"Our research discovered that the blood marker FCGR2A identifies a new group of patients that will benefit from taking cetuximab. With this finding, we believe we are now on the way to move it into the clinical setting to provide patients targeted, effective treatment," said principal investigator Dr. Geoffrey Liu, MSc, MD.

This new research builds upon a previous clinical trial from 10 years ago.

"In a group of metastatic colorectal cancer patients who were running out of treatment options, the previous clinical trial determined that cetuximab was most effective in a certain group of patients with tumors carrying a RAS mutation. But it certainly didn't work for everyone and so the race was on to find out how to better identify which patients would benefit from this drug," Dr Liu said. "Our finding, which resulted from analyzing archived tumor and normal tissue samples from some of the 572 patients enrolled in that trial, further refines this quest and defines another subset of patients who will respond to the drug.”

Researchers concluded there should be a better way to personize cancer therapy for patients with colorectal cancer because cetuximab is expensive and has side effects.

“So instead of looking at aspects in the tumor, which is where RAS mutations show up, we looked at certain things in the blood and normal tissues that we could measure for heritable genetic variations,” Dr Liu said about the current study.

The researchers said their findings are an ideal example of the results from continuing to follow a drug and research outcomes.

"When we followed the drug, first in lung cancer and then in other cancers, it led us to colorectal cancer where the drug was also being used, and directly onto this new finding,” Dr Liu concluded.