A View from Emily Singer
A Blood Test for Cancer
A microfluidics chip that captures rare cancer cells is headed for commercialization.
A microfluidics chip designed to capture cancer cells circulating in the blood is taking a step closer to clinical use, thanks to a new partnership between Massachusetts General Hospital (MGH) and Veridex, a diagnostics company owned by Johnson and Johnson. According to a release from the company, the technology “will enable [circulating tumor cells] to be used both by oncologists as a diagnostic tool for personalizing patient care, as well as by researchers to accelerate and improve the process of drug discovery and development.”
The prototype, developed by Mehmet Toner and collaborators at MGH, consists of a business-card-size silicon chip dotted with tens of thousands of microscopic posts. Each post is coated with a molecule that binds to a protein unique to cells from a specific type of tumor, such as breast, lung, or prostate cancer. As blood flows through the chip, tumor cells stick to the posts. In 2007, the researchers first showed that the chip could capture these rare cells–which make up just one in a billion cells in blood–in high enough numbers to analyze them for molecular markers.
The ultimate goal is to use the device to tailor cancer treatments to individual patients by monitoring cancer cell counts and by identifying the molecular attributes of an individual’s cancer. For example, specific markers can highlight a more aggressive form of cancer or a tumor that will respond to specific cancer drugs, while genetic changes in the tumor might signal the need to change treatments.MGH and four other research institutions, have already received a $15 million grant from the organization Stand Up to Cancer to test the prototype. But that technology is expensive and complicated to use, with each chip costing about $500, according to the Boston Globe.
“We’re limited by our ability to make it fast, easy, cheap, and something that could be done on a global scale,” said Dr. Daniel Haber, director of the MGH Cancer Center, and one of the device’s designers, told the Globe. “Our goal is to build together a third-generation technology… that would be so easy to use and so standard, it wouldn’t have to be a research tool.”
Such blood tests could ultimately prove to be an inexpensive and noninvasive complement to the CT scans and tissue biopsies that oncologists traditionally use to characterize tumors. For example, regular blood tests assessing tumor cell count might be used to determine if a particular treatment is effective.
While Veridex already sells a diagnostic test that can count circulating tumor cells, the test does not analyze the cells for specific molecular markers, similar to the tests pathologists now perform on tumor tissue collected during surgery or from needle biopsies. For example, researchers have shown the device can isolate enough cells to detect a specific mutation in a gene for the epidermal growth factor receptor. The mutation suggests that patients will respond to drugs designed to inhibit this pathway. (Other researchers have shown that the FDA-approved device can also detect a molecular marker linked to drug response.)
Toner’s group recently developed a new version of the chip that can capture even more cells. The inner surface of the device has a herringbone design, which generates a vortex in the blood flowing through it. This mixing brings the cells in greater contact with antibodies on the surface of the chip. According to research published last year in the Proceedings of the National Academy of Sciences, this chip could detect isolated clusters of tumor cells, which may help shed light on cancer’s ability to spread, or metastasize, from its initial birthplace.
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