Chemotherapeutic apoptosis inducer. An orally active alkylating agent prodrug, delivering a methyl group to purine bases of DNA (O6-guanine; N7-guanine and N3-adenine). Temozolomide has demonstrated efficacy in the treatment of a variety of solid tumors, primary malignant brain tumors and metastatic melanoma (IC50 value 5 μM for cytotoxicity against mouse TLX5 lymphoma cells).
The primary cytotoxic lesion, O6-methylguanine (O6-MeG) can be removed by methylguanine methyltransferase (MGMT; direct repair) in tumours expressing this protein, or tolerated in mismatch repair-deficient (MMR-) tumours.