A new nanotechnology-based treatment developed by researchers at the University of Texas’s Southwestern Medical Center at Dallas could double the effectiveness of cancer drugs without increasing side effects, while allowing doctors to see immediately whether the treatment is working.
Nanotechnology-based drug treatments are already starting to be approved for use, but so far they are neither very precise nor very potent. Current cancer-fighting nanomedicine, which involve little more than nanoscopic containers packed with chemotherapy drugs, reaches tumors by leaking through holes in tumor blood vessels and gradually releasing a drug. To kill appreciable amounts of the tumor this way, doctors must flood the body with these drug-bearing nanocarriers, says Jinming Gao, associate professor of oncology and pharmacology at the University of Texas Southwestern Medical Center at Dallas. These can get soaked up by the body’s natural filters, such as the liver and spleen, in which they can cause side effects, he says.
What’s more, doctors can’t get a good view of what’s happening once nanocarriers are administered. They don’t know whether the nanocarriers are reaching targets or delivering drugs until they remove tissue from the patient, the tumor starts to shrink, or the first side effects appear. It’s like fighting cancer in a “black box,” Gao says.
Now a growing cadre of researchers are developing next-generation nanomedicine platforms that can both deliver drugs only to cancer cells and allow doctors to monitor the progress of the treatment. The University of Texas system delivers both an anti-cancer drug and a highly effective magnetic resonance imaging (MRI) contrast agent to allow doctors to see that the drug is being delivered to a tumor. The nanocarriers are made of polymers with an inner core that traps doxorubicin, a common chemotherapy drug, and iron-oxide particles that show up clearly with MRI. Polymer strands on the outside of the nanocarrier bear targeting molecules that are recognized only by tumor blood-vessel cells. The nanocarriers latch on to the vessel cells, and the cells engulf the carriers. The polymer releases the drug once inside the cell, where it is most effective.
Tests on cells grown in the lab showed promising results, says Gao. Nanocarriers equipped with the targeting molecule delivered twice the amount of drug and killed twice the number of cells (94 percent) as those without it, he reported online in the journal Nano Letters.”We could detect as few as 50,000 cells,” Gao says. Studies in mice are now in progress.