Study: Nanotherapy slams brain tumors with high rad doses

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Researchers at the University of Texas Health Science Center at San Antonio have developed a way to deliver nanoparticle radiation directly to glioblastoma and contain the dose within the tumor, according to a study published March 19 in Neuro-Oncology.

The method doses the tumor with 20 to 30 times the current dose of radiation therapy to patients but spares a much greater area of brain tissue. Thus, the animal study indicates the method overcomes a critical limit of conventional radiotherapy for glioblastoma: as radiation passes through healthy brain tissue to reach the tumor, patients can only tolerate small amounts before developing serious side effects.

“We saw that we could deliver much higher doses of radiation in animal models,” Andrew Brenner, MD, PhD, a neuro-oncologist at the Cancer Therapy & Research Center (CTRC), said in a statement.

Following the successful preclinical study, Brenner and colleagues plan to launch a clinical trial this summer.

The researchers placed rhenium-186, an isotope with a short half-life, inside the tumor. The rhenium emits radiation that only extends out a few millimeters. To keep the rhenium in the tumor, researchers encapsulated the isotope in liposomes, about 100 nanometers across.

Brenner and colleagues reported delivery of dose up to 1850 Gy without overt clinical or microscopic evidence of toxicity. Rats treated with the method had a median survival of 126 days, compared with 49 days for controls.

Finally, Brenner et al wrote, “An additional attribute of this potential therapy, evident in noninvasive SPECT imaging, is the capacity for real-time image feedback and iterative modulation of nanoparticle brachytherapy with real-time dosimetry calculations of the delivered 186Re-liposomes to provide the most accurate treatment and ensure complete tumor coverage.” They added that retreatment could be possible with this method as doses to the surrounding brain tissue are very low.