Temozolomide is not directly active but undergoes rapid nonenzymatic conversion at physiologic pH to the reactive compound 5-(3-methyltriazen-1-yl)-imidazole-4-carboxamide (MTIC). The cytotoxicity of MTIC is thought to be primarily due to DNA alkylation, mainly at the O6 and N7 positions of guanine, which causes DNA double strand breaks and results in programmed cell death.

Temozolomide is an alkylating drug indicated for the treatment of adults with:
•    Newly diagnosed glioblastoma concomitantly with radiotherapy and then as maintenance treatment.
•    Anaplastic astrocytoma.
o    Adjuvant treatment of adults with newly diagnosed anaplastic astrocytoma.
o    Treatment of adults with refractory anaplastic astrocytoma.