Early Tests Find Nanoshell Therapy Effective Against Brain Cancer
Rice University bioengineers and physician-scientists at Baylor College of Medicine and Texas Children's Hospital have successfully destroyed tumors of human brain cancer cells in the first animal tests of a minimally invasive treatment that zaps glioma tumors with heat. The tests involved nanoshells, light-activated nanoparticles that are designed to destroy tumors with heat and avoid the unwanted side effects of drug and radiation therapies.
Jennifer West, from Rice, and Susan Blaney, from Baylor, led the team that conducted this research. The investigators published the results of their study in the Journal of Neuro-Oncology.
In their paper, the researchers reported that more than half of the animals that received the nanoshell treatment for glioma tumors had no signs of cancer more than three months after treatment. "This first round of in vivo animal tests suggests that photothermal therapy with nanoshells may one day be a viable option for glioma patients," said Dr. West. She cautioned that follow-up work in the laboratory is needed before any human testing of the therapy can begin, adding that human clinical trials of nanoshell phototherapy for glioma are likely at least a year away.
Glioma is among the most aggressive and difficult-to-treat of all brain cancers. Fewer than five percent of glioma patients survive beyond five years. The disease is particularly difficult to treat because glioma tumors are often highly invasive and inoperable.
The researchers injected the mice with gold nanoshells and waited 24 hours for the nanoparticles to accumulate in the tumors. Laser-generated near-infrared light, which passes safely through biological tissues was shined on the tumor for three minutes. The nanoshells converted the laser light into tumor-killing heat. All seven animals that received the nanoshell treatment responded, but cancer returned in three. The other four remained cancer-free 90 days after treatment.
"The results of this study are encouraging, and we are cautiously optimistic that this process may bring us closer to finding a cure for glioma," said Dr. Blaney. "This is very exciting, especially given the poor prognosis of the disease and the importance of finding brain tumor treatment alternatives that have minimal side effects."
Gold nanoshells were invented in the mid-1990s by Naomi Halas, a colleague of Dr. West's at Rice. Dr. Halas is the co-principal investigator of the Cancer Nanotechnology Platform Partnership at Rice, one of 12 funded by the National Cancer Institute. Nanoshells are like tiny malted milk balls that are coated with gold rather than chocolate. Their core is non-conducting, and by varying the size of the core and thickness of the shell, researchers can tune them to respond to different wavelengths of light. Houston-based biomedical firm Nanospectra Biosciences, which holds the license for medical use of Rice's nanoshell technology, began the first human clinical trial of nanoshell phototherapy in 2008. Dr. West, a co-founder and director of Nanospectra Biosciences, said the new glioma study is part of a larger ongoing effort within the Texas Medical Center to adapt nanoshell phototherapy for use against a variety of cancers.
This work, which was funded in part by the National Cancer Institute, is detailed in a paper titled, "Nanoshell-mediated photothermal therapy improves survival in a murine glioma model." An abstract of this paper is available at the journal's website.