Finding Cancer Cells in the Blood
In the near future, oncologists may be using a finger-size plastic chip with tiny channels to extract a dozen or so cancer cells from a sample of a patient’s blood. Those cells, called circulating tumor cells, could then be screened for genetic disruptions that an oncologist could target with drugs best suited to attacking the tumor. Continued sampling would give doctors a way to monitor whether a treatment is working and decide whether to add or change a drug as the malady evolves.
Dozens of companies are vying for success in this market, which is expected to reach $7.9 billion in the next few years, but so far only one device, sold by a Johnson & Johnson subsidiary, has received FDA approval. That current technology is not able to detect circulating tumor cells when they’re present only in very small numbers, says Daniel Haber, director of the Massachusetts General Hospital Cancer Center, and cannot capture the full diversity of cells that escape from different tumor types in patients. But advances are already proven in labs and may be making their way to clinics in the next few years, experts say.
Working with biomedical engineer Mehmet Toner and his team at MGH, Haber is developing their latest chip into a commercial product. The new chip design can pull out any cancer cell that might be floating in the blood and keep it alive so pathologists can do genomic and molecular tests on it (see “Device Finds Stray Cancer Cells in Patients’ Blood”). The results of such tests are valuable because pharmaceutical companies are increasingly developing cancer drugs with specific molecular targets in mind. These targeted therapies stand to improve cancer treatment. Cancer genomics company Foundation Medicine says that as many as 70 percent of tumors it analyzes carry genetic signatures that can inform treatment (see “Cancer Genomics”).
Although the scientific and medical community has long known that cancer spreads through the bloodstream, there has been no way to capture the circulating tumor cells. “These are rare cells in the midst of 100 billion other cells,” says Toner. “Microfluidics gave us an opportunity to more precisely manipulate the blood and see if these cells are there in a useful number.”