Targeted method improves treatment of brain cancers

Researchers in the US have developed a way of delivering nanoparticle radiation directly to a brain tumour and retaining it at the site.

Current radiotherapy treatments target beams of radiation to the tumour site, which pass through healthy tissue also. Patients receiving treatment can only tolerate small amounts before developing serious side effects.

The method, developed at the University of Texas Health Science Center at San Antonio, doses the tumour with much higher levels of radiation — 20 to 30 times the current dose of radiation therapy to patients — but is said to spare a much greater area of brain tissue.

The study, published in the journal Neuro-Oncology, has been successful enough in laboratory experiments for the team to prepare 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 at the CTRC who will lead the clinical trial.

‘We saw that we could deliver much higher doses of radiation in animal models,’ said Brenner. ‘We were able to give it safely and we were able to completely eradicate tumours.’

The radiation comes in the form of rhenium-186, which has a short half-life. Once placed inside the tumour, the rhenium emits radiation that only extends out a few millimetres.

Putting the rhenium into a brain tumour would not work well without a way to keep it there as the particles would be picked up by the bloodstream and carried away.

That problem was solved by encapsulating the rhenium in fat molecules (liposomes) measuring approximately 100nm across.

Brenner told The Engineer via e-mail that delivering the treatment requires the use of a stereotactic guidance system called Brainlab to guide a needle to the injection site.

‘We then insert a catheter, specifically developed for use in brain tumours and developed by Brainlab, through the needle directly to the target,’ he said. ‘The needle is removed and the catheter remains in place.’

Brenner added that the rhenium is infused through the catheter using continuous pressure while the flow is monitored under Spect [Single-photon emission computed tomography] imaging.

The team, which includes William T Phillips, MD, Beth A Goins, PhD; and Ande Bao, PhD, all of the School of Medicine at the UT Health Science Center, hopes to launch the clinical trial by summer.