AAPM: Nanoparticles with radioisotopes developed to treat tumors
In a presentation on Tuesday at the 2009 American Association of Physicists in Medicine (AAPM) meeting in Anaheim, Calif., researchers at Johns Hopkins University in Baltimore described the design of nanoparticles that can carry cancer-treating radioisotopes through the body and deliver them to selective tumors.

The Hopkins researchers are using commercially-available liposomes that have been modified with antibodies to create immunoliposomes, which will wend their way through the bloodstream and seek out tumors inside the body. When they come into contact with their target cells, they deliver their payload into the cells.

"It's a promising approach to solving the problem of how to deliver more of a therapeutic [dose] to cancer cells," said lead researcher George Sgouros, MD, a radiology professor at Hopkins.

Similar studies by other groups of researchers have demonstrated how immunoliposomes could be packaged with radioactive tracers used for imaging tumors. However, Sgouros and his colleagues have sought to reproducibly package more powerful radioisotopes, called alpha-particle emitters, which have the capability to kill cancer cells without damaging nearby normal cells.

Early results show that they can pack a relatively large dose of radionuclides into the liposomes and use them to successfully treat mice with a very aggressive type of metastatic breast cancer, according to the Hopkins researchers.

"This treatment is much less toxic than chemotherapy because it is targeted to tumor cells rather than to all rapidly dividing cells," Sgouros said. "Nanoparticles designed to deliver these powerful isotopes have a great potential in cancer therapy, particularly for metastatic disease."