Temozolomide-induced severe myelosuppression: analysis of clinically associated polymorphisms in two patients.

Genotyping of putative determinants of temozolomide (TMZ)-induced life-threatening bone marrow suppression was performed in two patients with glioma treated with adjuvant TMZ and radiation therapy. DNA was extracted from the patients' mononuclear cells and genotyping of O-methylguanine-DNA-methyltransferase (MGMT), multidrug resistance (MDR1; also known as ABCB1), NQO1, and GSTP1 genes and analysis for the epigenetic silencing of specific MGMT gene promoters were carried out to evaluate the possible genetic determinants of increased risk of severe TMZ-induced myelosuppression. Although both patients were heterozygous for all ABCB1 single nucleotide polymorphisms and for rs12917 and rs1803965 in the MGMT gene, patient 1 was heterozygous for rs1695 in GSTP1 and rs2308327 in the MGMT gene.