December 20, 2007

Microchip-based device can detect rare tumor cells

Investigators from the MGH BioMicroElectroMechanical Systems (BioMEMS) Resource Center and the MGH Cancer Center have developed a microchip-based device that can isolate, enumerate and analyze circulating tumor cells (CTCs) from a blood sample. CTCs are viable cells from solid tumors carried in the bloodstream at a level of one in a billion cells.

"This use of nanofluidics to find such rare cells is revolutionary, the first application of this technology to a broad, clinically important problem," says Daniel Haber, MD, director of the MGH Cancer Center and a co-author of the report in the Dec. 20 issue of Nature. "The approach raises the possibility of rapidly and noninvasively monitoring tumor response to treatment, allowing changes if the treatment is not effective, and the potential of early detection screening in people at increased risk for cancer."

A lung cancer cell (green) adheres to an anti-body covered micropost in the CTC chip.

Microchip-based technologies have the ability to accurately sense and sort specific types of cells from samples the size of a single drop of fluid. Since CTCs are so rare, detecting them in useful quantities requires analyzing samples that are 1,000 to 10,000 times larger. To meet that challenge, the MGH BioMEMS Resource Center research team — led by Mehmet Toner, PhD, director of the center in the MGH Department of Surgery, and Ronald Tompkins, MD, ScD, chief of the MGH Burn Unit — investigated factors required for microchip analysis of sufficiently large blood samples.

The device they developed, called the CTC-chip, utilizes a business-card-sized silicon chip, covered with almost 80,000 microscopic posts coated with an antibody to a protein found on most solid tumors. Using the chip to analyze blood from cancer patients showed it was able to capture CTCs in 99 percent of the samples and did not incorrectly indicate the presence of CTCs in any control samples. "We looked at four major cancer killers and were able to consistently find these cells and correlate test results with traditional monitoring techniques," Toner says.

Considerable work needs to be done before the CTC-chip is ready to be put to clinical use, and the MGH investigators are establishing a Center of Excellence in CTC Technologies to further explore the potential of the device.