Breakthrough liquid biopsy chips may supersede biopsy devices in the near future

Worcester Polytechnic Institute (WPI) mechanical engineers have developed a unique chip that traps and diagnoses metastatic cancerous cells from a small blood sample taken from a patient suffering from cancer. This revolutionary, one-of-a-kind technology uses an easy mechanical method proven to be more effective than a microfluidic based approach used in current diagnostic devices in the biopsy devices market. This liquid biopsy, described in detail in the journal Nanotechnology, could potentially become the basis for quick and easy lab tests that could detect initial signs of metastasis and help medical practitioners choose the appropriate treatment to target particular cancer cells.

The spread of cancer throughout the body and across organs through the bloodstream is a process known as metastasis. Prognosis of metastatic cancer is quite poor, so a technology that could detect these circulating tumour cells prior to their forming additional tumour colonies at different sites around the body could greatly increase the patient's odds of survival. The medical focus on circulating tumour cells is a recent development as it is a challenging task for medical practitioners. There are billions of red blood cells, hundreds of thousands of white blood cells but a very small number of tumour cells in a cancer patient’s body, meaning a very high degree of precision is required to isolate cancerous cells.

The new liquid biopsy device comprises a sequence of small elements, each 3 millimetres wide, with a well, the bottom of which includes antibodies attached to carbon nanotubes. Every well has a particular antibody that binds to only one specific cancer cell type, based on surface genetic markers.  The device is used to capture many cancer cells from one blood sample by seeding the elements with a variety of antibodies. In one lab study, researchers could fill 170 such wells using about 0.85 millilitres of blood. The carbon nanotubes used in liquid biopsy devices act as semiconductors. When a cancer cell binds to an attached antibody, it creates an electric signal that can be detected. These signals are then used to identify which elements have been able to capture cancer cells. The individual arrays can be removed and taken to a laboratory, where the cells may be studied and identified under the microscope. In lab tests, the binding and electric signature generation only take a few minutes, meaning that it could even be possible to get same day blood test results with the liquid biopsy chip.

Along with capturing cancer cells, the liquid biopsy chip can latch onto exosomes produced by cancer cells that have identical markers. These chips can potentially locate exosomes and circulating tumour cells directly, improving their ability to diagnose metastasis. This is particularly important as new evidence shows that tiny proteins that are excreted along with exosomes can cause adverse reactions that are likely to hamper effective cancer treatment or drug delivery. White blood cells can be a major problem as they are the most numerous and can easily be mistaken for cancerous cells. With the help of passive leukocyte depletion strategy, the cancer cells settle at the bottom of the well, where they meet the antibodies. The rest of the blood remains at the top of the well and can be quickly washed away.

While a liquid biopsy device is currently used to detect breast cancer, it could eventually detect different types of tumours. Development plans are well underway for devices to detect pancreatic and lung cancer. There is a great potential for these devices to be used not only on those patients who already have cancer but also in routine detection screenings. Cancer can be detected at the earliest possible development stage, enabling doctors to customise treatment on the basis of specific cancer markers of each patient. Thus, patients would truly be able to take their health into their own hands.