There is already one diagnostic tool on the market for identifying and counting CTCs in blood samples, but it is not optimized for early detection. The U.S. Food and Drug Administration (FDA) in 2004 approved the CellSearch system, made by Johnson & Johnson's Veridex unit, for identifying and counting CTCs in patients with metastatic breast cancer. The FDA has since cleared CellSearch to help guide treatment of metastatic forms of prostate and colorectal cancer as well. Last year Johnson & Johnson said it would invest $30 million in a partnership with Massachusetts General Hospital to further develop CellSearch.
Despite these planned upgrades, "the U.C.L.A. work has promise as an advance over what is currently available," says Leon Esterowitz, a program director at the National Science Foundation (NSF). CellSearch is used primarily to check the progress of cancer treatment, whereas U.C.L.A.'s imaging technology could find cancerous cells at an earlier stage, before they can form a new tumor. "They've greatly improved the sensitivity and speed of the techniques that are being used for instance by Johnson & Johnson," Esterowitz says.
Researchers at New York City's Weill Cornell Medical College and Cornell University College of Engineering in Ithaca are also developing a cancer blood test, although theirs uses a "geometrically enhanced differential immunocapture" (GEDI) silicon chip that can identify and collect cancer cells from a patient's blood sample. The chip works in a device that can determine when patients have a high concentration of rare cancer cells from metastatic prostate cancer, according to the researchers, who described their work in the April 2012 issue of PLoS ONE. GEDI, like CellSearch, would be used to determine the efficacy of the patients' chemotherapy rather than finding early-stage cancer cells.
Esterowitz notes that all these blood tests are effective only after cells have become cancerous. He points to a Northwestern University project that aims to illuminate precancerous cells. Northwestern researchers are analyzing tissue at the nano—as opposed to the micro—scale to root out cells whose nuclei have greatly expanded or otherwise show irregularities that could be signs of impending malignancy.
Northwestern's approach, led by biomedical engineer Vadim Backman, involves shining light on tissue either inside a patient's body or taken from it. The researchers use a combination of microscopy and spectroscopy to examine how that light is reflected. Fluctuations in the reflections indicate possible abnormalities in the sampled tissue's micromolecular density and may flag the presence of unhealthy cells, Backman says.
"Most effort in the past has been studying cancer cells and tumors themselves, but we're focusing on what precedes the tumor," Backman says. "The tumor is the tip of the iceberg. We want to look below the waterline."
Backman and his team claim to have already tested their technology on 2,000 patients with a high degree of accuracy. The next step is to develop a compact, easy-to-use version that could be commercialized, and then conduct additional tests to earn FDA approval for what could be an even more effective cancer early warning system.