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Scanner detects earliest sign of cancer

STANFORD (US)—Early detection can be the difference between life and death for many cancer patients. A new blood scanner shows promising signs of helping doctors detect cancer at its earliest stage, allowing for early treatment and a better chance of survival.

A team led by Stanford University researchers has developed a prototype of the scanner that can find cancer markers in the bloodstream in less than an hour and with much greater sensitivity than existing commercial devices. In fact, the scanner, which uses magnetic nanotechnology to spot the cancer proteins, is tens to hundreds of times more sensitive, meaning the proteins can be found while there are relatively few of them in the bloodstream.

Shan Wang, a Stanford professor of materials science and of electrical engineering, is optimistic the technology will someday save lives by detecting cancer early or by helping doctors select more effective therapy.

“The earlier you can detect a cancer, the better chance you have to kill it,” he says. “This could be especially helpful for lung cancer, ovarian cancer, and pancreatic cancer, because those cancers are hidden in the body.”

The handheld device—perhaps the smallest of its kind in the world—is able to detect many different kinds of proteins at the same time, which is important for two reasons, Wang notes. First, researchers are still uncertain which cancer biomarkers are the best diagnostic indicators. Second, detecting multiple biomarkers simultaneously will allow a doctor to diagnose more specifically the kind of cancer a patient may have.

The specialty of Wang’s research group at Stanford is magnetic nanotechnology. Magnetism is rare in biological systems, so any magnetic signal in a blood serum sample stands out like a flare in the night sky. By tagging cancer proteins with tiny magnetic particles, rather than electrically charged or glowing particles as in other detectors, the new system can obtain a clearer signal from a smaller number of cancer proteins.

At the heart of the detector is a silicon chip, designed by the paper’s lead author, Sebastian Osterfeld, a Stanford doctoral student in materials science and engineering. The chips have 64 embedded sensors that monitor for changes in nearby magnetic fields. Attached to these sensors are “capture antibodies,” painstakingly selected by Heng Yu, formerly a postdoctoral fellow at the Stanford Genome Technology Center, and graduate student Richard Gaster.

The sensor’s “capture antibodies” grab specific cancer-related proteins as they float by and hold onto them. Then a second batch of antibodies is added to the mix. They latch onto magnetic nanoparticles as well as the cancer biomarkers that are being held captive by the sensors. Thus when the MagArray sensors detect the magnetic field of nanoparticles, they’ve found cancer markers as well.

In the paper, the researchers estimate they could detect levels of the human chorionic gonadotropin protein at a level about 400 times lower than the level required for detection by current commercial kits known by the acronym ELISA, in which captured cancer proteins are tethered to color-altering or fluorescent labels.

At Stanford Medical Center, the detector is viewed as a potentially significant clinical advance, according to a diagnostics expert there.

“This work represents a giant leap forward in enabling technology for in vitro protein diagnostics with significant potential for many applications including cancer detection and management,” says Sam Gambhir, the principal investigator of the Center of Cancer Nanotechnology Excellence at Stanford.

To properly prepare a patient’s blood sample for use with the detector, a technician must use a centrifuge to separate out the serum, which contains the biomarkers. For this reason, the device must be located in a hospital or a private diagnostic lab, Wang said. But before then it must face clinical testing and trials to win regulatory approval. To see the detector through those steps, Wang has cofounded a startup company, MagArray Inc., in the Panorama Institute for Molecular Medicine, a not-for-profit incubator in Sunnyvale, Calif.

The nascent startup is also investigating the possible use of the detectors in emergency rooms to quickly check for heart attacks when patients arrive with chest pains. Like cancer, heart cell death is associated with the release of specific biomarker proteins.

Stanford University news: http://news.stanford.edu

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