Researchers go to great lengths to collect data straight from the source, designing rovers that can search for water on Mars and robots that sniff around at thermal vents on the ocean floor. Now a team of chemical engineers, material scientists, and molecular imaging researchers at the Massachusetts Institute of Technology is developing a rodshaped implant that will allow doctors to explore inner space, providing the capability to monitor malignant tumors from inside the tumor itself.

The 2-millimeter device, which is inserted using a biopsy needle, holds nanoparticles that have been specially engineered to attract certain substances - tumor markers in some cases and chemotherapy drugs in others. Once inside, the targeted molecules cling to the nanoparticles, causing them to bunch up. While the nanoparticles themselves are not a new concept, the implant’s walls are. Made of silicone, they are porous, allowing external molecules to enter but keeping the all-important nanoparticles inside. Doctors can examine the concentration of the targeted molecule through localized MRI scans.

Consider one common cancer marker, the hormone known as human chorionic gonadotropin. If a high concentration of this target molecule is detected, it would indicate that the tumor is as large as or larger than in earlier tests, and that an administered drug is not reaching it. In general, knowing concentrations of these tumor markers as well as tumor metabolism indicators, such as oxygen, pH, and glucose, can help physicians determine a tumor’s growth and progress.

If an MRI scan shows coagulation of nanoparticles engineered to detect a treatment drug - say, herceptin, which is used to fight breast cancer - the therapy has effectively reached the tumor. If these nanoparticles have not clumped, a physician may decide to change the dosage or move on to another drug altogether. By monitoring tumors and treatments at the molecular level inside the body, doctors can get a faster and more accurate read of a drug’s effectiveness than would be possible through blood testing.

This type of molecule-specific data is at the center of the growing field of targeted cancer therapies. “We’re going to see a proliferation of highly targeted agents for certain cancers,” says MIT professor Michael Cima, who launched the study nearly two years ago. “Doctors will quickly know if a particular agent is the right one to give, rather than waiting for the tumor to go away to make that decision.”

The study, which is conducted by the MIT-Harvard Center of Cancer Nanotechnology Excellence and is funded by the National Cancer Institute, has proven in early tests that this approach can detect cancer markers more rapidly than full-body MRI scans. Preclinical trials in animals will begin this spring. - Erika Stalder