Temozolomide

Temozolomide is an oral alkylating chemotherapy drug that damages tumor-cell DNA. It is used mainly to treat glioblastoma and other certain brain tumors.

DNA alkylation: The addition of alkyl groups to DNA bases, which can disrupt replication and gene expression. Temozolomide’s active products alkylate DNA, producing lesions that can trigger tumor-cell death.
Glioblastoma: An aggressive diffuse primary brain tumor composed of malignant glial-lineage cells. Temozolomide is a standard component of treatment for many newly diagnosed cases.
Imidazotetrazine: A fused heterocyclic chemical framework found in temozolomide and related compounds. This framework gives temozolomide its unusual ability to decompose into an active methylating species.
Myelosuppression: Reduced production of blood cells by bone marrow, increasing risks such as infection and bleeding. This is a major dose-limiting toxicity of temozolomide.
MGMT promoter methylation: Methylation of regulatory DNA near the MGMT gene that is associated with reduced MGMT expression. It is a clinically used biomarker associated with greater temozolomide benefit in glioblastoma.
O6-methylguanine: A DNA lesion formed when a methyl group attaches to guanine’s oxygen at position six. This lesion is a key source of temozolomide’s cytotoxic effect.
Anaplastic astrocytoma: A historically defined grade III infiltrating astrocytic tumor, now classified within molecularly defined adult-type diffuse gliomas. Temozolomide has been used to treat this high-grade astrocytic tumor.
Prodrug: A compound converted in the body into a pharmacologically active drug. Temozolomide undergoes chemical conversion in the body before generating its DNA-reactive products.
Thrombocytopenia: An abnormally low platelet count in the blood. Temozolomide can suppress platelet production and require treatment interruption or dose adjustment.
IDH mutation: A cancer-associated mutation in a gene encoding isocitrate dehydrogenase 1 or 2. IDH status helps define glioma types and influences interpretation of temozolomide treatment evidence.

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