Radio Waves Heat Nanotubes Embedded in Tumors, Destroying Liver Cancer

Cancer cells treated with carbon nanotubes can be destroyed by noninvasive radio waves that heat up the nanotubes while sparing untreated tissue.

A research team led by scientists from the University of Texas M.D. Anderson Cancer Center (Houston, TX, USA) and Rice University (Houston, TX, USA) has shown in preclinical experiments that the technique completely destroyed liver cancer tumors in rabbits. Furthermore, there were no side effects noted. However, some healthy liver tissue within 2-5 mm of the tumors sustained heat damage due to nanotube leakage from the tumor.

"These are promising, even exciting, preclinical results in this liver cancer model,” stated senior author Steven Curley, M.D., professor in M.D. Anderson's department of surgical oncology. "Our next step is to look at ways to more precisely target the nanotubes so they attach to, and are taken up by, cancer cells while avoiding normal tissue.”

Targeting the nanotubes exclusively to cancer cells is the major challenge in advancing the therapy, according to Dr. Curley. Research is under way to bind the nanotubes to antibodies, peptides, or other agents that then can target molecules expressed on cancer cells. To complicate matters, most of these molecules also are expressed in normal tissue.

Dr. Curley estimates that a clinical trial is at least three to four years away. He conducted the research at M.D. Anderson in collaboration with nanotechnology specialists at Rice University and with Erie, Pennsylvania, entrepreneur John Kanzius of ThermMed LLC (Erie, PA, USA), who invented the experimental radio frequency generator used in the experiments.

In the liver cancer study, a solution of single-walled carbon nanotubes was injected directly into the tumors. Four treated rabbits were then exposed to two minutes of radio frequency treatment, resulting in thermal destruction of their tumors. Carbon nanotubes are hollow cylinders of pure carbon that measure approximately one billionth of a meter, or 1 nm, across. Control group tumors that were treated only by radio frequency exposure or only by nanotubes were undamaged.

In lab experiments, two lines of liver cancer cells and one pancreatic cancer cell line were destroyed after being incubated with nanotubes and exposed to the radio frequency field. "I'm humbled by the results of this research,” commented Mr. Kanzius. "I realize it's early in the race, but Dr. Curley and his team have moved on this carefully with utmost speed. I look forward to continuing to work with them and hopefully to watching the first person be treated with this procedure. The race isn't over but it needs to be taken to the finish line.”

Radio frequency energy fields penetrate deeply into tissue, so it would be possible to deliver heat anywhere in the body if targeted nanotubes or other nanoparticles can be delivered to cancerous cells, according to Dr. Curley. Without such a target, radio waves will pass harmlessly through the body.

An invasive technique known as radio frequency ablation is used to treat some malignant tumors, the investigators noted. It requires insertion of needle electrodes directly into the tumors. Incomplete tumor destruction occurs in 5-40% of cases, healthy tissue is damaged, and complications arise in 10% of patients who suffer such damage. Radio frequency ablation is limited to liver, kidney, breast, lung, and bone cancers.

The research was published online in November 2007 in advance of the December 2007 publication in the journal Cancer.


Related Links:
University of Texas M.D. Anderson Cancer Center
Rice University