Fat-Enclosed Nanoparticles Designed to Effectively Irradiate Brain Tumors

Radiation has long been the most effective way to treat deadly brain tumors called glioblastomas. Although the targeting strategy has been refined, beams of radiation still must pass through healthy brain tissue to reach the tumor, and patients can only endure small amounts before developing serious side effects. A group of scientists have created a technique to deliver nanoparticle radiation directly to the brain tumor and keep it there.

This approach doses the tumor itself with much higher levels of radiation--20 to 30 times the current dose of radiation therapy to patients--but spares a much greater area of brain tissue. The study, published March 21, 2012, in the journal Neuro-Oncology, has been successful enough in laboratory experiments that they are preparing to launch a clinical trial at the Cancer Therapy & Research Center (CTRC), according to Andrew Brenner, MD, PhD, the study’s corresponding author and a neuro-oncologist from the University of Texas (UT) Health Science Center at San Antonio (USA), who will lead the clinical trial. “We saw that we could deliver much higher doses of radiation in animal models,” Dr. Brenner said. “We were able to give it safely and we were able to completely eradicate tumors.”

The radiation comes in the form of an isotope called rhenium-186, which has a short half-life. Once positioned inside the tumor, the rhenium emits radiation that only extends out a few millimeters.

But merely placing the rhenium into a brain tumor would not work well without a way to keep it there--the miniscule particles would be captured by the bloodstream and carried away. That hurdle was resolved by a team led by nuclear medicine physician William T. Phillips, MD, and biochemist Beth A. Goins, PhD, in the department of radiology; and Ande Bao, PhD, a medical physicist, and pharmaceutical chemist in the department of otolaryngology, all of the School of Medicine at the UT Health Science Center. They encapsulated the rhenium in miniscule fat molecules, known as liposomes, about 100 nm across.

“The technology is unique,” Dr. Brenner said. “Only we can load the liposomes to these very high radioactivity levels.”

The researchers plan to begin the clinical trial by the summer of 2012.

Related Links:
University of Texas Health Science Center at San Antonio