Prognostic Significance of NQO1 Polymorphism and GST-M1 Deletion in De Novo Acute Myeloid Leukemia

Background: Although the most powerful prognostic factor of acute myeloid leukemia (AML) patients is the karyotype of the leukemic blast, data have not been obtained almost entirely in patients with heterogeneous cytogenetics. Further, some patients with favorable cytogenetics may show the poor treatment outcomes. Previous reports suggested that the single nucleotide polymorphisms of genes coding drug detoxification enzymes such as cytochrome P450 family or DNA repair system may influence the treatment outcomes in the patients with AML. We evaluated the role of polymorphisms in XRCC1, XRCC4, CYP1A1, GST-T1, GST-M1, NOQ1, and NAT2*6A in predicting therapeutic outcomes of adults with AML.

Methods:XRCC1 (rs25487), XRCC4 (rs1056503), NQO1 (rs1800566), CYP-4501A1*2B (rs1048943), NAT2*6A (rs1799930) gene polymorphisms and deletion of GST-M1/GST-T1 were evaluated in 460 bone marrow (BM) samples obtained at initial diagnosis from de novo AML patients. Genotyping method is pyrosequencing using genomic DNA from BM samples. Homozygous deletions of GST-M1 and GST-T1 genes were detected with a multiplex PCR technique. All patients except APL (acute promyelocytic leukemia) received one or two rounds of intensive induction chemotherapy consisting of 3 days of idarubicin and 7 days of cytarabine. APL patients treated with AIDA regimen consisting of 45 days of ATRA (all-trans retinoic acid) and 3 days of idarubicin.

Results: Of total 460 patients, ninety-nine patients (21.5%) were APL. Seventy-one (15.4%) were AML with t(8;21), twenty-three (5%) were AML with inv(16), and 179 patients (38.9%) showed normal cytogenetics. The median age of patients was 44 years (range, 14–75 years). In all cytogenetic risk group, the patients carrying homozygous NQO1 gene polymorphism (TT) showed significantly lower rate of complete remission (CR) than in those with negative or heterogyzous polymorphisms (TT: 72.7% vs. CC/CT: 85.9%, p=0.03). There was no significant difference in relapse rate, leukemia-free survival (LFS) and overall survival between homo- and heterozygote groups in these polymorphsims. In subgroup analysis, APL patients carrying TT genotype in NQO1 also showed lower rate of CR (TT: 77.8% vs. CC/CT: 95.4%, p=0.04). In AML patients except APL, NQO1 homozygous polymorphsim (TT) was also associated with lower CR rate (TT: 69.6% vs. CC/CT: 84.2%, p=0.005). In normal cytogenetics, the patients with del GST-M1 showed shorter LFS compared with those carrying GST-M1 (18.0 ± 5.7ms. vs. 34.6 ± NA. p=0.04).

Conclusions: This study revealed an association between NQO1 polymorphism and GST-M1 deletion and the treatment outcomes for AML patients. Further study and larger sample size are needed to reach the definite conclusion on these associations. However, a stratified treatment plan in remission induction chemotherapy such as augmentation or addition of other chemotherapeutic agents may be warranted for AML patients harvoring homozygous NQO1 polymorphism (TT) or del GST-M1.