ASCO GI Interview Series: Robert Rosenberg, MD, Discusses Advantages of ColoPrint Test

Charles Bankhead
Published: Wednesday, Mar 02, 2011
At the 2011 symposium in San Francisco, California, Oncology & Biotech News spoke with the author of one of the featured presentations at the meeting. Robert Rosenberg, MD, of the Technical University of Munich in Germany, presented results from a retrospective evaluation of the ColoPrint test in patients with stage II colon cancer. Derived from a genome-wide search, the 18-gene microarray test is designed to distinguish highrisk from low-risk patients, leading to more informed clinical decision making about patients who will and will not benefit from adjuvant chemotherapy. The end result should be more efficient use of therapy in patients who need it and avoidance of toxicity and cost in patients who are unlikely to benefit. As Rosenberg explained in the following discussion, the results he presented suggest that the test might be superior to currently available clinical information used to identify patients who have stage II colon cancer and are most likely to benefit from adjuvant chemotherapy.

OBTN: Could you briefly discuss the underlying technology of this test?

Rosenberg: I was not directly involved in the development of the test. I was involved in the evaluation of it, so my understanding of the ColoPrint test is from that perspective. The test was developed from the whole genome, not a candidate-gene approach, where you would look for the most important genes that might be involved in development of a kind of cancer. The candidate-gene approach was the approach used to develop the OncoType test. For the ColoPrint test [researchers] used patients from the Netherlands to identify a prognostic gene set. From the whole genome, they identified 18 genes that correlated with colon cancer in the patients.

Then in the second step, they transferred these 18 genes in a test set. They combined these 18 genes with housekeeping genes, so it's a microarray platform. When the RNA is extracted from the tissue, depending on the gene expression profile, they get values which were identified as high risk or low risk.

The test has been evaluated in 2 validation studies, and additional studies are ongoing. Additionally, a multicenter prospective evaluation is being conducted, involving centers in the United States, Europe, and Asia. That study will involve about 600 patients with colon cancer.

The cutoff points for this test appear to be really robust, so they can clearly say whether the patient is high risk or low risk. Other tests have intermediate areas where it is not clear whether the test correlates with a high-risk or low-risk patient.

Is the ColoPrint test designed for a specific group or subset of patients with colon cancer? What types of patients would be good candidates for the test?

It seems best suited for patients with stage II colon cancer. Those are patients who have medium- or large-size tumors--which can be T3 or T4 tumors--with no lymph node involvement or distant metastases. These are patients who generally have a good prognosis, with a 5-year survival in the range of 85% to 90%. We know that even in this stage there are 25% to 30% of patients who do not have such a good prognosis. The ColoPrint test uses different parameters where we can identify the 25% to 30% of patients who clearly have the worst prognosis. We haven't [yet established] hard parameters to identify these patients. We have the American Society of Clinical Oncology (ASCO) recommendations, but even [the ASCO parameters] are not very [specific]. So, it seems that this test will help us identify some of these patients for whom we do not have good parameters to determine their prognosis.

From the perspective of a practicing oncologist, could you take us through the steps or the process involved in obtaining results with the ColoPrint test?

We are surgeons, and when we perform the operation we take a specimen and give it immediately to the pathologist, who comes to the operating room. We have that advantage that might not be available everywhere--the pathologist in the operating room. The pathologist determines the tumor size, which is important to be sure that we achieved the correct resection and that we are fine with respect to the resection. Then we remove a 0.5-cm piece of the specimen and immediately insert the tissue into a stabilization solution provided by the [ColoPrint] manufacturer. The tissue is then sent to the manufacturer.

At the moment I cannot say how long the wait will be to get the test result for future patients. This was a retrospective analysis that we presented at this meeting. We are currently participating in a prospective multicenter clinical trial, and we don't receive the results immediately. I would guess that the results would be ready within 1, 2, 3 days, but I don't know for sure.

How might the results of the test influence your decision making about the management of a specific patient? If the results showed the patient to be low risk, high risk, or in the middle, how would that affect your approach to treatment?

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