[Editors] MIT implant monitors tumors

[Elizabeth Thomson]

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MIT’s implantable device offers continuous cancer monitoring
--New device could track tumor’s growth
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For Immediate Release
WEDNESDAY, MAY. 13, 2009

Contact: Elizabeth A. Thomson, MIT News Office
E: thomson at mit.edu, T: 617-258-5402

Photo Available

CAMBRIDGE, Mass.--Surgical removal of a tissue sample is now the  
standard for diagnosing cancer. Such procedures, known as biopsies,  
are accurate but only offer a snapshot of the tumor at a single moment  
in time.

Monitoring a tumor for weeks or months after the biopsy, tracking its  
growth and how it responds to treatment, would be much more valuable,  
says Michael Cima, MIT professor of materials science and engineering,  
who has developed the first implantable device that can do just that.

Cima and his colleagues recently reported that their device  
successfully tracked a tumor marker in mice for one month. The work is  
described in a paper published online in the journal Biosensors &  
Bioelectronics in April.

Such implants could one day provide up-to-the-minute information about  
what a tumor is doing — whether it is growing or shrinking, how it’s  
responding to treatment, and whether it has metastasized or is about  
to do so.

“What this does is basically take the lab and put it in the patient,”  
said Cima, who is also an investigator at the David H. Koch Institute  
for Integrative Cancer Research at MIT.

The devices, which could be implanted at the time of biopsy, could  
also be tailored to monitor chemotherapy agents, allowing doctors to  
determine whether cancer drugs are reaching the tumors. They can also  
be designed to measure pH (acidity) or oxygen levels, which reveal  
tumor metabolism and how it is responding to therapy.

With current tools for detecting whether a tumor has spread, such as  
biopsy, by the time you have test results it’s too late to prevent  
metastasis, said Cima.

“This is one of the tools we’re going to need if we’re going to turn  
cancer from a death sentence to a manageable disease,” he said.

In the Biosensors & Bioelectronics study, human tumors were  
transplanted into the mice, and the researchers then used the implants  
to track levels of human chorionic gonadotropin, a hormone produced by  
human tumor cells.

The cylindrical, 5-millimeter implant contains magnetic nanoparticles  
coated with antibodies specific to the target molecules. Target  
molecules enter the implant through a semipermeable membrane, bind to  
the particles and cause them to clump together. That clumping can be  
detected by MRI (magnetic resonance imaging).

The device is made of a polymer called polyethylene, which is commonly  
used in orthopedic implants. The semipermeable membrane, which allows  
target molecules to enter but keeps the magnetic nanoparticles trapped  
inside, is made of polycarbonate, a compound used in many plastics.

Cima said he believes an implant to test for pH levels could be  
commercially available in a few years, followed by devices to test for  
complex chemicals such as hormones and drugs.

Lead author of the paper is Karen Daniel, a recent MIT PhD recipient.  
Other authors are recent PhD recipients Grace Kim and Christophoros  
Vassiliou; Marilyn Galindo, research affiliate in the Harvard-MIT  
Division of Health Sciences and Technology; Alexander Guimares, a  
radiologist at Massachusetts General Hospital; Ralph Weissleder, a  
professor of radiology at Harvard Medical School; Al Charest, visiting  
assistant professor of biology at MIT; and Institute Professor Robert  
Langer.

The research was funded by the National Cancer Institute Centers of  
Cancer Nanotechnology Excellence and the National Science Foundation.

--END--

Written by Anne Trafton, MIT News Office
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