Histological assessment of neuronal integrity was performed in mice treated with INCB7839 or vehicle control. The cortex, CA1 region of the hippocampus and dentate gyrus of the hippocampus were examined immunohistologically in the hemisphere contralateral to glioma xenografts in mice treated with INCB7839 or vehicle control. Brain sections were immunostained with NeuN (green) to mark neuronal nuclei and cleaved caspase-3 (red) to mark apoptotic cells and counterstained with DAPI (blue). Representative sections from n = 4 INCB7839-treated mice and n = 4 vehicle control mice were examined. Neuronal nuclei appeared morphologically normal and non-pyknotic. Extremely few cleaved caspase-3+ cells were identified in either group; a total of one cleaved caspase-3+ cell was found in each group across all mice examined (white arrows). Scale bar, 200 μm.