Competing Tests for Colorectal Cancer Risk Recurrence

Caroline Helwick

April 2011, Vol 2, No 2 - Genitourinary Cancers Symposium

San Francisco, CA—The optimal treatment of early-stage colorectal cancer (CRC) is not well-established. At the 2011 Gastrointestinal Cancers Symposium, several studies presented involved molecular assays that stratify patients according to a tumor’s genetic profile.

18-Gene ColoPrint Assay Outperforms Clinical Variables
One study reported validation results from an 18-gene assay. “The ColoPrint facilitates the identification of patients with stage II CRC with a low risk of recurrence and who therefore don’t need chemotherapy,” said Robert Rosenberg, MD, PhD, of Technical University Munich.

Of the 27% of patients who were classified as high-risk by the ColoPrint assay, 80.5% were free of distant metastases at 5 years compared with 94.9% of those classified as low-risk.

This test also outperformed the clinical parameters recommended by the American Society of Clinical Oncology for patients with stage II CRC. “No other prognostic genetic profile in colorectal cancer has been subjected to a second validation,” Dr Rosenberg said. Studies are under way in this country and internationally.

Commenting on this assay, Wells Messersmith, MD, Director of the Gastrointestinal Medical Oncology Program at the University of Colorado, Denver, was concerned that this test only tells us who not to treat. “I want a test that tells me who to treat, and the ColoPrint assay only tells me who I probably should not be treating— the good-risk patients. I also want to know the subset of ‘poor-risk’ patients who will benefit from adjuvant chemotherapy.”

5-Gene OncoDefender Validated, Superior to NCCN Guidelines
A 5-gene assay claims to be doing that. First validation results for the OncoDefender were announced at the meeting by Peter F. Lenehan, MD, PhD, Chief Medical Officer of Everist Genomics, Ann Arbor, MI, who evaluated this test at 3 Mayo Clinic sites.

The study included 115 patients with stage I and II CRC treated only by surgery. The 5-gene test differentiated the risk of recurrence among earlystage patients more accurately than did estimates using the National Comprehensive Cancer Network guidelines. The test correctly classified 32 of 46 patients with recurrence, and 38 patients of 69 without.

High-risk patients had a significantly greater probability of recurrence than low-risk patients.

Dr Lenehan said the OncoDefender stands out among a growing list of competitors in higher positive predictive value and better sensitivity. Most tests have good negative predictive value, he said. “It is more clinically significant and cost-effective to define who is at high risk for recurrence. Our test can say with more confidence that a patient has a tumor that is aggressive and will recur.” He added, “Our test is the first to also target stage I patients.” Approximately 15% of patients with stage I disease will turn out to have aggressive disease.

OncoDefender should become available soon, at a cost of $3400, with a patient assistance program. Gene assays used in breast cancer cost $3000 to $4000. The Oncotype DX Recurrence Score is already available for CRC, but it is not reimbursed by all payers.