Levetiracetam therapeutically targets GABAergic synapses in diffuse midline glioma

Antiseizure medications, such as levetiracetam, are commonly used in glioma patients. Retrospective analyses evaluating effects of antiseizure medications on glioma patient survival have yielded inconsistent results, probably due to confounding factors of glioma subtype and drug class. Here we present retrospective real-world clinical data that demonstrate longer overall survival for children with diffuse midline glioma (DMG) who were taking levetiracetam, which was not evident in pediatric patients with hemispheric high-grade glioma. In preclinical models, levetiracetam reduces glioma proliferation and tumor burden, extending survival of mice bearing DMG orthotopic xenografts. These beneficial effects were not found in hemispheric high-grade glioma patient-derived orthotopic xenograft models. The subtype-specificity of this antiproliferative effect of levetiracetam is congruent with recent findings that GABAergic neuron-to-glioma synapses promote glioma growth in DMG but not hemispheric high-grade glioma. We demonstrate here that levetiracetam attenuates low-frequency GABAergic synaptic transmission in a glioma-specific manner, reducing GABAergic synaptic currents in DMG but not in healthy neurons. This effect is independent of action on SV2A, the chief mechanism by which levetiracetam functions to prevent and treat seizures. Taken together, these findings indicate a promising approach to target GABAergic synapses in DMG and suggest that use of levetiracetam in DMG should be further studied in future prospective clinical studies.