Scientists in Germany are developing a microchip sensor that can be implanted near a tumor to monitor its growth aggressiveness, by sensing when oxygen levels in surrounding tissue drop, thus giving doctors and patients the opportunity to gauge when best to plan surgery or treatment. The sensor is expected to be of great benefit to people who have tumors in places where it is difficult to operate or where surgery could impair quality of life, such as patients with brain or prostate cancer. The researchers also hope the microchip device will help deliver cancer drugs in a more targeted way that is less aggressive for patients.
Known by the project name IntelliTuM (Intelligent Implant for Tumor Monitoring), the microchip sensor is the brainchild of a team of medical engineers led by professor Bernhard Wolf of the Technische Universitaet Muenchen (TUM), where he is the Heinz Nixdorf Chair of Medical Electronics.
Currently, the decision of when to time surgery or treatment requires patients with difficult to treat or slow growing tumors to keep going to hospital for frequent tests. The idea behind the new implantable sensor is that it keeps an eye on the tumor, and sends frequent updates electronically to the doctor who is monitoring the patient remotely.
The IntelliTuM sits inside a biocompatible plastic housing and comprises a small sensor chip with electronics onboard to do some preliminary analysis, a transmitter and a battery; the whole thing is barely twice the size of a human thumbnail.
Implanted close to the tumor, the chip measures the amount of dissolved oxygen in the surrounding tissue and transmits, without wires, the information to a receiver carried by the patient. The receiver then forwards the information to the patient’s doctor.
Project manager and engineer Sven Becker, told the press last week that they designed the chip to “self-calibrate to a set dissolved oxygen concentration at measurement intervals”.
Surgery is often one of the first therapy options when a person discovers they have cancer. But some tumors, such as brain tumors, are difficult to operate on because of the significant risk of damaging surrounding tissue. Other cancers, such as prostate cancer, have tumors that grow very slowly, and often the patient is quite elderly. In such cases, an operation would most likely impair quality of life without necessarily giving them many more years.
Currrently at the prototype stage, the IntelliTuM has passed lab tests using cell and tissue cultures. Before it can be tested in humans the device will first have to pass trials in animals.
The main challenge for the engineers was to devise a sensor that operates by itself for long periods. The next step is to ensure it remains accurate when it gets contaminated with protein and cell debris, and stays “invisible” to the body’s immune defences, which would engulf it in tissue once it identified it as a “foreign object”.
Plus, before it can be implanted with minimally invasive surgery into patients, the device has to be even smaller than the current prototype. The engineers also want to add other sensors on board, to measure temperature and acidity.
There are also plans for the device to carry a tiny medication pump that can release chemotherapy drugs right next to the tumor.
Funding for the project came from the Heinz Nixdorf Stiftung and a EUR 500,000 grant from Germany’s Federal Ministry of Education and Research.
Written by Catharine Paddock PhD