Study shows drug may help even more people suffering from colorectal cancer.
New research from the Canadian Cancer Trials Group (CCTG) has discovered that a new subset of patients with metastatic colorectal cancer could benefit from taking the drug cetuximab.
Senior investigator Chris O'Callaghan with the Queen's University-based CCTG worked with lead researcher Geoff Liu from the Princess Margaret Cancer Centre and the Australasian Gastro-Intestinal Trials Group on the research.
"These patients were running out of time and options," says Dr. O'Callaghan. "With this finding, we believe we are now on the way to move it into the clinical setting to provide patients with targeted, more effective treatment."
The new research builds on an international clinical trial conducted 10 years ago. Working with a group of metastatic colorectal cancer patients with few treatment options remaining, researchers determined that cetuximab was most effective for patients with tumours carrying a RAS mutation, a protein that often signals cancer.
Cetuximab didn't work for everyone, though, so Dr. O'Callaghan and his colleagues worked to improve the identification of patients who would benefit from the drug. By analyzing archived tissue samples from 572 patients enrolled in the original trial, they were able to define another subset of patients who will respond best to the drug.
"We need to find other ways to personalize cancer medicine for people with colorectal disease, keeping in mind that cetuximab is an expensive drug and can have side effects," Dr. O'Callaghan says. "So instead of only looking at aspects in the tumour, which is where RAS mutations show up, we looked at certain things in the blood and normal tissues. This is how we discovered the blood marker that this subset of patients has in common."
Researchers are now working to confirm the results in multiple studies, which will be used to guide clinical decision making. A new study that will be used to validate the results, CO.20, is already underway.
The research was published in Clinical Cancer Research.
Fc-γ Receptor Polymorphisms, Cetuximab Therapy, and Survival in the NCIC CTG CO.17 Trial of Colorectal Cancer. Geoffrey Liu,*, Dongsheng Tu, Marcia Lewis, Dangxiao Cheng, Leslie A. Sullivan, Zhuo Chen, Eric Morgen, John Simes, Timothy J. Price, Niall C. Tebbutt, Jeremy D. Shapiro, G. Mark Jeffery, J. Daniel Mellor, Thomas Mikeska, Shakeel Virk, Lois E. Shepherd, Derek J. Jonker, Christopher J. O'Callaghan, John R. Zalcberg, Christos S. Karapetis, and Alexander Dobrovic. Clinical Cancer Research. DOI:10.1158/1078-0432.CCR-15-0414. Published online May 15, 2016.