Stanford Medicine researchers found that children with diffuse midline gliomas who had taken a common anti-seizure drug had roughly twice the median survival time of those who had not taken it.

The study, published Thursday, Sept. 17, in the journal Nature Medicine, showed that levetiracetam, sold under the brand name Keppra, slows the growth of diffuse midline gliomas by severing the tumors' electrical connections to healthy brain cells. The tumors strike the brainstem, thalamus and spinal cord of 300 to 400 U.S. children each year. The five-year survival rate is about 1%.

"This drug pharmacologically severs an important connection between cancer and the nervous system," Michelle Monje, the study's senior author and the Milan Gambhir Professor in Pediatric Neuro-Oncology and professor of neurology at Stanford Medicine, said in a Stanford Medicine news release.

Researchers analyzed medical records from 218 pediatric brain tumor patients treated at Stanford University and the University of Michigan. Among 119 children with diffuse midline gliomas, the 15 who had taken levetiracetam survived a median of nearly 21 months. The 104 who had not taken it survived a median of about 10 months.

Two independent groups of patients, one at the University of California, San Francisco, and one at University Medical Center Hamburg-Eppendorf in Germany, showed the same trend toward longer survival.

The drug did not help patients with a different type of brain tumor, hemispheric high-grade gliomas, which originate in other parts of the brain. Mouse models confirmed that pattern. Levetiracetam blocked electrical signals through GABAergic synapses in tumor cells but left healthy neurons alone, a mechanism the researchers described as tumor-specific.

That anti-tumor action works through a different molecular pathway than the one that prevents seizures, according to the Nature Medicine paper. The exact pathway in tumor cells remains unknown.

Levetiracetam is already widely prescribed to brain tumor patients for seizure prevention because it has few side effects and does not interact with other medications. That existing safety record lowers the barrier to testing it as a cancer treatment.

The study's lead author, Tara Barron, was a postdoctoral scholar at Stanford Medicine during the research and is now an assistant professor of pathology at the University of Texas Southwestern Medical Center. Researchers from UCSF, Hamburg-Eppendorf and the University of Helsinki also contributed.

Monje's team is launching a clinical trial of levetiracetam for patients with diffuse midline gliomas. Her lab is also running a separate trial studying CAR-T cells, immune cells engineered to attack brain tumors, in children with the same cancer.

The authors cautioned that the retrospective clinical data are limited by small patient numbers and that prospective clinical trials are needed before drawing firm conclusions.