The Antiepileptic Drug Oxcarbazepine Inhibits the Growth of Patient-Derived Isocitrate Dehydrogenase Mutant Glioma Stem-like Cells

SIMPLE SUMMARY: Patients diagnosed with isocitrate dehydrogenase (IDH)-mutated brain tumors frequently suffer from seizures, and the seizures were shown to promote tumor growth. Anti-seizure medications (antiepileptic drugs) might be able to break this vicious circle. However, it is not yet known which antiepileptic drugs might have additional anti-tumor effects. In this study, 20 commonly used antiepileptic drugs were tested on patient-derived tumor models. Only oxcarbazepine promoted additional tumor cell killing, making it an interesting drug to use in this special population of brain tumor patients. ABSTRACT: Patients diagnosed with isocitrate dehydrogenase mutant (IDH(mut)) gliomas suffer frequently from seizures. Although the clinical course is less aggressive than that of its IDH wildtype counterpart, recent discoveries have shown that epileptic activity can promote tumor proliferation. However, it is not known if antiepileptic drugs confer additional value by inhibiting tumor growth. In this study, the antineoplastic properties of 20 FDA-approved antiepileptic drugs (AEDs) were tested in six patient-derived IDH(mut) glioma stem-like cells (GSCs). Cell proliferation was assessed using the CellTiterGlo-3D assay. Two of the screened drugs (oxcarbazepine and perampanel) demonstrated an antiproliferative effect. A subsequent eight-point dose–response curve proved the dose-dependent growth inhibition for both drugs, but only oxcarbazepine reached an IC(50) value below 100 µM in 5/6 GSCs (mean 44.7 µM; range 17.4–98.0 µM), approximating the possible c(max) for oxcarbazepine in patient serums. Furthermore, the treated GSC spheroids were 82% smaller (mean volume 1.6 nL vs. 8.7 nL; p = 0.01 (live/dead(TM) fluorescence staining)), and the apoptotic events increased by more than 50% (caspase-3/7 activity; p = 0.006). Taken together, this drug screen of a large series of antiepileptic drugs identified oxcarbazepine as a potent proapoptotic drug in IDH(mut) GSCs, which combines antiepileptic and antineoplastic properties to treat this seizure-prone patient population.