Nonviral gene therapy shrinks brain tumors in rats

Rat glioma cells treated in culture. Left: Ganciclovir alone has no effect on glioma cells. Right: Glioma cells killed by combination of ganciclovir and HSVtk-encoding nanoparticles.--Courtesy of ACS Nano/NIBIB

A global team of scientists working with Johns Hopkins' Jordan Green has developed a new nonviral gene therapy for brain cancer, successfully testing it in the lab in cell lines as well as rat models for the disease.

Using a polymer dubbed PBAE 447, the scientists created a cargo of DNA encoding a gene known as HSVtk. That gene in turn creates an enzyme that changes the drug ganciclovir into a toxin for glioma cells. And it worked in two cell lines for glioma--with 100% efficiency in extinguishing cancer cells--as well as in the rats, shrinking tumors and extending the lives of the rodents.

The big idea here is that scientists hope to try and test this approach with the initial surgical response to a diagnosis of brain cancer. And later they plan to try a more systemic approach to see how it works for other cancers.

"The results provide the first demonstration of a successful non-viral nanomedicine method for HSVtk/ganciclovir treatment of brain cancer," stated Green. "Next steps will include enhancing the efficiency of this nanoparticle delivery system and evaluating the technology in additional brain cancer animal models."

The investigators particularly hit on the added safety of a nonviral gene therapy strategy, highlighting old concerns that using a virus could in turn trigger an immune response or spawning new tumors. In recent years, though, a number of biotechs have been launched to prove that using benign viruses isn't the threat it once was.

Brain cancer, though, remains one of the toughest of all cancers to treat, usually leaving newly diagnosed patients with only a short time to live. And any new strategies that promise to shrink tumors or extend lives would likely get close scrutiny.

The National Institute of Biomedical Imaging and Bioengineering funded the work, which was carried out by Green, colleagues from the Johns Hopkins University School of Medicine Departments of Neurosurgery, Oncology, Ophthalmology, and Pathology, as well as Tang Du Hospital in China, University of the Negevin, Israel, and the Instituto Neurologico C. Besta in Italy.

- here's the release

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