"Cornell Dots" — brightly glowing nanoparticles — may soon be used to light up cancer cells to aid in diagnosing and treating cancer. The U.S. Food and Drug Administration has approved the new technology for the first clinical trial in humans. It is the first time the FDA has approved using an inorganic material in the same fashion as a drug in humans.
The trial with five melanoma patients at Memorial Sloan-Kettering Cancer Center will seek to verify that the dots are safe and effective in humans, and to provide data to guide future applications.
"This is the first product of its kind," said Dr. Michelle Bradbury, assistant professor of radiology at Weill Cornell Medical College and a radiologist at MSKCC. "We want to make sure it does what we expect it to do."
Ulrich Wiesner, the Spencer T. Olin Professor of Materials Science and Engineering at Cornell University in Ithaca, has spent eight years researching and developing the nanoparticles.
"C dots" are silica spheres less than eight nanometers in diameter that enclose several dye molecules. The silica shell is chemically inert and small enough to pass through the body and out in the urine. For clinical applications, the dots are coated with polyethylene glycol so the body will not recognize them as foreign substances.
To make the dots stick to tumor cells, organic molecules that bind to tumor surfaces or even specific locations within tumors can be attached to the dots' shell. When exposed to near-infrared light, the dots fluoresce much brighter than unencapsulated dye to serve as a beacon to identify the target cells. The technology, the researchers say, can show the extent of a tumor's blood vessels, cell death, treatment response, and invasive or metastatic spread to lymph nodes and distant organs.
Dr. Michelle Bradbury
For the human trials, the dots will be labeled with radioactive iodine, which makes them visible in PET scans to show how many dots attach to tumors and where else in the body they go and for how long.
"We do expect the dots to go to other organs," Dr. Bradbury said."We get numbers, and from that curve derive how much dose each organ gets. And we need to find out how fast it passes through. Are they cleared from the kidney at the same rate as in mice?"
One of many advantages of C dots, Dr. Bradbury noted, is that they remain in the body long enough for surgery to be completed. "Surgeons love optical," she said. "They don't need the radioactivity, but [our study] confirms what the optical signal is. As you learn that, eventually you no longer need the radioactivity."
On the other hand, she added, the dots also may serve as a carrier to deliver radioactivity or drugs to tumors. "This is step one to jump-start a process we think will do multiple things with one platform," she said.