Magnetic Drug Targeting May Help Reach CNS Tumors

Targeted delivery of nanoparticles may reduce systemic and CNS toxicity in spinal cord tumors.

It may be possible to improve outcomes in patients with hard-to-reach spinal tumors. Researchers at the University of Illinois at Chicago (UIC) are reporting that magnetic nanoparticles may provide a novel therapeutic approach for high-grade intramedullary spinal cord tumors.

The team developed doxorubicin-loaded magnetic nanoparticles that were conjugated with doxorubicin. According to the study, published in the journal Scientific Reports, the researchers successfully localized these nanoparticles to a xenografted tumor in a rat model. The study suggests this approach may provide an effective, concentrated delivery of chemotherapeutic agents to intramedullary spinal cord tumors, without the toxicity of systemic administration.

“We found that chemotherapy in the form of magnetically guided nanoparticles could be utilized effectively for intramedullary spinal cord tumors,” said study investigator Ankit Mehta, MD, assistant professor of neurosurgery and director of spinal oncology at the UIC College of Medicine. “We demonstrated cell death in a spinal cord tumor model.”

Mehta and colleagues note that intramedullary spinal cord tumors account for 8%–10% of all spinal cord tumors and are common among children and adolescents. Average survival for patients with these tumors is reportedly 15.5 months. Currently, five nanocarriers have already been approved by the US Food and Drug Administration, and several others are undergoing clinical investigation and development, according to the study authors.

Doxorubicin is commonly used to treat spinal tumors and is delivered intravenously, but there tends to be poor penetration to the spine. Radiation therapy is also problematic for spinal tumors because the radiation often damages nearby healthy spinal tissue and can result in paraplegia.

Mehta and colleagues created nanoparticles made up of tiny, metallic magnets bound to particles of doxorubicin. They inoculated six athymic rats with 100,000 human glioblastoma multiforme cells, which were injected into the spinal cord. The team also implanted a neodymium magnet subdermally above the tumor inoculation site. The researchers then allowed the tumor to grow for 2 weeks. After 14 days, three rats received an intrathecal injection of doxorubicin-loaded magnetic nanoparticles at the L3/L4 vertebral level.

The researchers were able to show that tumor cells took up the nanoparticles and underwent apoptosis. The impact of the nanoparticles on nearby healthy cells was very minimal, according to Mehta. “Right now, the standard of care for spinal cord tumors, particularly high-grade astrocytomas, is biopsy and radiation with poor prognosis,” Mehta told Cancer Network. “This proof of concept gives hope to a patient population with spinal cord tumors that hopefully can be translated in patients. It provides a new paradigm of localized drug delivery to specific locations in the spinal cord.”