Temozolomide and radiation treatment tied to Dramatic Tumor Regression and Hearing Restoration in Adult Brainstem Glioma: Study with a rare IDH2 mutation

A group led by the Department of Neurosurgery at the Brain Research Institute, Niigata University, has successfully treated a patient with a brainstem glioma harboring a rare IDH2 mutation. The patient initially presented with a gradual loss of hearing in the left ear, and MRI showed a lesion at the left side of the brainstem, near the root exit zone of the left acoustic nerve. Initially, a brainstem glioma with H3K27M mutation was suspected. However, the gradual clinical course and unusual location of the brainstem glioma were considered atypical.

The patient underwent magnetic resonance spectroscopy in which 2-hydroglutarate, a marker for IDH mutation, was evident. Subsequently, the patient underwent a surgical biopsy, and pathological analysis revealed a rare IDH2 mutation. Although most brainstem gliomas with H3K27M mutation have an unmethylated MGMT promoter and thus are resistant to temozolomide, about 70% of IDH-mutant astrocytomas are known to have a methylated MGMT promoter and are sensitive to temozolomide.