Blood Test Advances Give Hope to Cancer Patients

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Blood Test Advances Give Hope to Cancer Patients

By: Madeline Ellis

Published: Friday, 4 July 2008

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To date this year, there have been 215,020 new cases of lung cancer diagnosed and 161,840 deaths due to lung cancer in the United States, according to National Cancer Institute estimates. Currently, the only sure way to know if lung cancer is present is for a pathologist to check samples of cells or tissues collected surgically from the patient. But a new test may one day not only replace those sometimes painful and difficult biopsies but also allow doctors to monitor changes in cancer cells and make necessary adjustments in treatment. This innovation requires just two teaspoons of blood and has been more than 90 percent effective in small clinical trials involving people with lung cancer.

Invented at Massachusetts General Hospital, the technology combines elements from two of the hottest fields in cancer research: tiny nanotechnology devices and personalized medicine tailored to treat individual patients. The CTC (Circulating Tumor Cells) chip is about the size of a business card. The chip is covered with 80,000 tiny columns that are coated with antibodies, which are designed to capture cancer cells but allow blood cells to flow past. Within about eight hours, it analyzes a patient's blood, identifying stray cells shed by tumors. "We can pick up very, very rare cancer cells that normally would originate in the lung or in the breast or in other types of tissues, and we can measure them in the blood," said Dr. Daniel Haber, director of the Massachusetts General Hospital Cancer Center in Boston.

Once the tumor cells are captured, their genetic fingerprints can help doctors determine the most effective treatment for a patient whose cancer has already begun spreading or to make sure a treatment is still working. In the future, doctors hope to use the test to determine if a tumor is growing, shrinking, or staying the same. "What we are learning now is that cancers are not always static. They can evolve. Their genetic composition can change. Their response to particular therapies can change, so it's very important to know what you are doing and what you are treating at the time that you are treating it," Dr. Haber said. Presently, tumor growth is measured using CT scans, usually every six to eight weeks. But because blood tests are easier to perform and don't expose patients to radiation, doctors would be able to test more frequently, as often as every week or two, allowing for closer monitoring.

For the pilot study, published online in the July 2 New England Journal of Medicine, Dr. Haber and colleagues analyzed blood samples from 27 patients with non-small cell lung cancer, 23 who had EGFR gene mutations and four who did not. Mutations in EGFR, a protein, can help predict whether tumors will respond to certain drugs called tyrosine kinase inhibitors. CTC's were identified in all samples and in genetic analyses from mutations 92 percent of the time. In a previous study, published in Nature, the CTC chip successfully found lung, pancreatic, prostate, breast and colon cancers in 99 percent of the samples. According to Dr. Haber, the CTC chip is 100 times more sensitive than a U.S. Food and Drug Administration-approved technique that uses magnetic beads to try to extract cancer cells.

Dr. Haber and colleagues hope to have a more automated machine that can process blood samples faster within a year, but FDA approval is likely years away. "This is still in a very, very early stage where it takes a long time to handle every sample, to flow the blood through the chip," he said. "This is a proof of principle that we can do this. We need a much more automated system for larger clinical trials."

Massachusetts General holds a patent on the test, which has been licensed to the privately held CellPoint Diagnostics in Mountain View, California. Dr. Haber, who has consulted for CellPoint, said he doesn't yet know the test's cost.

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