Researchers from the University of Michigan have developed and are now testing a device they call "the epitome of precision medicine" that detects cancer in circulating blood.
"Nobody wants to have a biopsy," says Dr. Daniel Hayes, the Stuart B. Padnos, Professor of Breast Cancer Research at the University of Michigan Rogel Cancer Center in Ann Arbor.
Biopsies are invasive and can be uncomfortable, yet they are currently the most accurate method of determining whether or not a person has cancer.
But, Dr. Hayes suggests, "If we could get enough cancer cells from the blood, we could use them to learn about the tumor biology and direct care for the patients."
Dr. Hayes and his team have recently developed a wearable device that can "filter" circulating blood for cancer cells that — if it passes all the tests — could replace liquid biopsies where healthcare professionals take blood or urine samples from individuals to look for markers of cancer.
Cancer tumors release cells into the blood, which means that, in theory at least, by taking a blood sample and analyzing it, a specialist should be able to detect the presence of cancer.
However, this is easier said than done, since, even in people who have malign tumors, blood samples may not reveal much, or anything at all, as cancer cells their tumors release into the blood circulate quickly, and may not show up in a single blood sample.
Spurred by this complication, Dr. Hayes and his University of Michigan colleagues have come up with a device that can do all the work of liquid biopsy testing but by actually "scanning" the bloodstream for cancer cells.
For the time being, the team has tested this device in dogs and reports the findings in the journal Nature Communications.
Challenges in reaching an effective design
The researchers explain that although most cancer cells that end up in the bloodstream do not survive for long, those that do survive may end up in different parts of the body and form a new, metastatic tumor.
For this reason, it is important to detect the presence of cancer as soon as possible and target it with adequate treatment, preventing it from spreading and doing further damage.
When they decided to try and develop a wearable device for the screening of cancer cells in the blood, Dr. Hayes and colleagues faced a series of obstacles that they had to circumvent.
Firstly, the device is about 2 by 2.75 by 1 inch in size, but it must fit all the technology of blood screening and analysis that typically amounts to machines as tall as a desk. Then, they had to find ways of making this wearable device effective and safe.
"The most challenging parts were integrating all of the components into a single device and then ensuring that the blood would not clot, that the cells would not clog up the chip, and that the entire device is completely sterile," explains the study's first author, Tae Hyun Kim, Ph.D.
The team did come up with some creative solutions for all these problems. Firstly, they found a way of mixing the blood running through the device with an anticoagulant (anti-blood clotting agent) — heparin. Then, they came up with a way of making sure that the device remained sterile without affecting the antibodies on the chip that help identify the cancer cells.
As for the chip that lies at the core of this device, the researchers explain that it uses graphene oxide to create a "filtering" mechanisms tipped with antibodies that are able to capture over 80 percent of cancer cells present in the blood.
'The epitome of precision medicine'
To test this device, the researchers worked with healthy dogs that they injected with human cancer cells. The team reassures that this treatment has no long-term effect on the animals whose immune systems get rid of the foreign cells within a few hours of the injection.
In their experiment, the investigators gave the dogs mild sedatives, during the first couple of hours following the cancer cell injections, and they then fitted the screening devices.
Additionally, the team collected blood samples from each animal every 20 minutes, and screened these for cancer cells separately, using chips with the same design as the ones they inserted in the experimental devices.
The researchers found that the wearable device identified and collected 3.5 times more cancer cells per milliliter of blood than the same chip did when "scanning" blood samples in vitro.
"It's the difference between having a security camera that takes a snapshot of a door every five minutes or takes a video. If an intruder enters between the snapshots, you wouldn't know about it," says study co-author Sunitha Nagrath, Ph.D.
In future studies, the researchers aim to perfect the wearable device by increasing its blood-processing rate. To test it further, in a more realistic context, the investigators then plan to use it on dogs that already have cancer.
While the new device has so far shown a lot of promise, Dr. Hayes believes that there is still a while to go until it becomes available to humans. He estimates that the team may be able to conduct clinical trials in human participants within 3 to 5 years.
"This is the epitome of precision medicine, which is so exciting in the field of oncology right now."
Dr. Daniel Hayes