¹Department of Infectious Diseases, Nagoya University School of Medicine, Nagoya, Japan

²Department of Medicine, Japanese Red Cross Nagoya First Hospital, Nagoya, Japan

³Department of Medicine, Saiseikai Maebashi Hospital, Maebashi, Japan

⁴Second Department of Internal Medicine, Kumamoto University School of Medicine, Kumamoto, Nagasaki, Japan

⁵Department of Hematology, Atomic Disease Institute Nagasaki University School of Medicine, Nagasaki, Japan

⁶First Department of Internal Medicine, Saitama Medical School, Saitama, Japan

⁷Second Department of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan

⁸Third Department of Internal Medicine, Dokkyo University School of Medicine, Tochigi, Japan

⁹Hematology Division, Tokyo Metropolitan Komagome Hospital, Tokyo, Japan

¹⁰Department of Hematology, Tokyo Women's Medical University, Tokyo, Japan

¹¹Second Department of Internal Medicine, Chiba University School of Medicine, Chiba, Japan

¹²Department of Medicine, Okayama University Medical School, Okayama, Japan

¹³Second Department of Internal Medicine, Nagoya City University School of Medicine, Nagoya, Japan

¹⁴Nagoya National Hospital, Nagoya, Japan

¹⁵Aichi Cancer Center, Nagoya, Japan

Correspondence to: T Naoe, Department of Infectious Diseases, Nagoya University School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8560, Japan; Fax: +81-52-744-2801

We investigated the prognostic significance of genetic polymorphism in glutathione-S transferase mu 1 (GSTM1), glutathione-S transferase theta 1 (GSTT1), NAD(P)H:quinone oxidoreductase (NQO1) and myeloperoxidase (MPO), the products of which are associated with drug metabolism as well as with detoxication, in 193 patients with de novo acute myeloid leukemia (AML) other than M3. Of the patients, 64.2% were either homozygous or heterozygous for GSTT1 (GSTT1⁺), while 35.8% showed homozygous deletions of GSTT1 (GSTT1^-). The GSTT1^- group had a worse prognosis than the GSTT1⁺ group (P = 0.04), whereas other genotypes did not affect the outcome. Multivariate analysis revealed that GSTT1^- was an independent prognostic factor for overall survival (relative risk: 1.53; P = 0.026) but not for disease-free survival of 140 patients who achieved complete remission (CR). The rate of early death after the initiation of chemotherapy was higher in the GSTT1^- group than the GSTT1⁺ group (within 45 days after initial chemotherapy, P = 0.073; within 120 days, P = 0.028), whereas CR rates and relapse frequencies were similar. The null genotype of GSTT1 might be associated with increased toxicity after chemotherapy.

Leukemia (2002) 16, 203-208. DOI: 10.1038/sj/leu/2402361

glutathione S-transferase; polymorphism; acute myeloid leukemia; prognosis

Introduction

In acute leukemia, prognosis depends on biological characteristics including morphology (FAB classification), immunophenotype, peripheral white blood cell (WBC) counts, chromosomal alterations, and many other molecular and phenotypic markers of leukemia cells.^1,2,3 Host-sided factors including the patient's age and performance status are also associated with the prognosis.^2,3,4,5 Genetic polymorphisms have been examined focusing on individual differences in pharmaco-dynamics, response, and the side-effects of drugs.⁶ However, it remains to be elucidated whether genetic polymorphisms influence the prognosis of leukemia after chemotherapy. Recently it was reported that the null genotype of glutathione-S transferase theta 1 (GSTT1) was associated with prognosis in childhood acute myeloid leukemia (AML).⁷

In this study, we analyzed the prognostic significance of gene polymorphism of GSTT1, glutathione-S transferase mu 1 (GSTM1), NAD(P)H:quinone oxidoreductase (NQO1) and myeloperoxidase (MPO), the products of which are associated with drug metabolism as well as with detoxication, in de novo acute myeloid leukemia (AML). Cytochrome P450 (CYP) 3A4 is also involved in metabolizing anti-cancer drugs but was not studied due to lack of polymorphism in the Japanese population.⁸

Materials and methods

Patients

The subjects included 193 patients with previously non-treated de novo AML other than M3, who were registered for the AML protocols conducted by the Japan Adult Leukemia Study Group (JALSG). Twenty-six, 39 and 128 patients were treated with the AML-87, AML-89 and AML-92 protocols, respectively.^9,10,11 AML samples were provided through 16 hospitals (about a quarter of JALSG institutes) for the purpose of molecular study after informed consent. AML was diagnosed according to the FAB classification, which was evaluated by a central review committee. Patients whose performance status was 3 or 4 (ECOG classification) were excluded from the registration.

In the AML-87 study,⁹ induction therapy consisted of daily behenoyl cytarabine (BHAC) 200 mg/m², daily 6-mercaptopurine (6-MP) 70 mg/m², daily prednisolone (PRD) 40 mg/m² and daunorubicin (DNR) 40 mg/m² on days 1 to 3, and if necessary on days 7, 8 and 11. The therapy was continued for a 10- to 12-day period until the bone marrow became severely hypoplastic with less than 5% blasts. In the AML-89 study,¹⁰ patients were randomized to receive induction therapy that included BHAC (200 mg/m² by 3 h infusion) or cytarabine (AraC, 80 mg/m² by continuous infusion). BHAC or AraC, and 6-MP 70 mg/m² were administrated for 10 to 12 days, and DNR 40 mg/m² was given on days 1 to 4, and if necessary, on days 10 to 12 in addition to the above schedule for AML-87. In the AML-92 study,¹¹ patients were randomized to receive BHAC-DM similar to the AML-87 protocol with or without etoposide (ETP, 100 mg/m² for 5 days). After complete remission (CR) was achieved, three courses of consolidation chemotherapy and six courses of intensification chemotherapy were given. Patients 60 years or older received about two-thirds of the dosage of each drug throughout the study period.

CR was defined as less than 5% blasts in normo-cellular bone marrow with normal levels of peripheral neutrophils and platelet counts. Overall survival was calculated from the first day of therapy to death. Disease-free survival (DFS) for patients who had achieved CR was measured from the date of CR to relapse or death. Relapse-free survival was defined as the time from the date of CR to relapse or death from progressive disease, censoring deaths from other causes. Patients who underwent bone marrow transplantation (BMT) were censored from the date of BMT.

Genotyping

The genotyping procedure for NQO1, GSTM1 and GSTT1 was described previously.⁸ Briefly, for the amplification of the NQO1 gene fragment, the sense and anti-sense primers were 5-AGTGGCATTCTGCATTTCTGTG-3 and 5-GATGGACTT GCCCAAGTGATG-3, respectively. The amplification was carried out in a thermocycler (model 9600; Applied Biosystems, Foster City, CA, USA) with an initial denaturation step (8 min, 95°C), followed by 35 cycles consisting of three steps: 94°C for 30 s, 56°C for 1 min and 72°C for 2 min. An additional cycle was performed at 72°C for 10 min. The amplified fragments were digested with HinfI endonuclease (New England Biolabs, Beverly, MA, USA) and analyzed on agarose gel electrophoresis. The paired primers for GSTM1 and GSTT1 were 5-GAACTCCCTGAAAAGCTAAAGC-3 and 5-GTTGGGCTCAAATATACGGTGG-3, and 5-TTCCTTACTGGTCCTCACATCTC-3 and 5-TCACCGGATCATGGCCAGCA-3, respectively. The presence or absence of GST genes was determined by a differential PCR in which the -globin gene was co-amplified in the same reaction tube. The primers for -globin were 5-ACACAACTGTGTTCACTAGC-3 and 5-CAACTTCATCCACGTTCACC-3. The MPO gene polymorphism located 463 bp upstream of exon 1 in the promoter region was examined.¹² Briefly, a 567-bp DNA fragment was amplified using 5'-AGGCCAATTGGGTCATCTTTACTC-3' and 5'-GACGGTTATCTTGCTCTGTT-3', with a second amplification using 5'-AGGAACCCTGGATAAACAGTGTAACC-3' and 5'-GCCTCTAGCCACATCATCAATT-3'. The reaction comprised 30 cycles of 94°C for 30 s, 55°C for 2 min and 72°C for 2 min. An additional cycle was performed at 72°C for 10 min. The final PCR products were digested with AciI (New England Biolabs). In cases of G/G and A/A at 463, two fragments (189 and 154 bp) and one fragment (343 bp) were obtained, respectively.

Statistical analysis

Survival probabilities were estimated by the Kaplan-Meier method, and differences in the distributions between the genotypes were evaluated using the log-rank test. The prognostic significance of the clinical variables was assessed using the Cox proportional hazards model. These statistic analyses were performed with StatView software (Abacus Concepts, Berkeley, CA, USA). For all analyses, P values were two-tailed, and a P value of less than 0.05 was considered significant. Since CR rates, overall survival and DFS according to induction therapy (AML-87, -89 and -92) did not show any differences, the data of the three studies were combined and analyzed.

Results

On genotyping, 124 of 193 patients (64.2%) were found to be either homozygous or heterozygous for GSTT1 (GSTT1⁺), while 69 patients (35.8%) showed homozygous deletions of GSTT1 (GSTT1^-). The GSTT1 genotype was related neither to age, sex, FAB subtype, WBC counts, nor karyotype abnormalities. There was no association among the four genotypes (GSTT1, GSTM1, NQO1 and MPO) (Table 1).

At a median follow-up time of 50 months, 64 (33.2%) patients were alive. The GSTT1^- group had a worse overall survival than the GSTT1⁺ group (P = 0.04, by the log-rank test, Figure 1). The predicted overall survival rates at 50 months were 33.7% and 22.1% in the GSTT1⁺ and GSTT1^- groups, respectively (Figure 1). DFS in 140 patients who achieved CR was compared between GSTT1⁺ and GSTT1^- groups. However, there was no significant difference (Figure 1).

Multivariate analysis of overall survival revealed that an age of 60 or more, unfavorable karyotype, and GSTT1^- were independent factors for a poor prognosis, and WBC over 100 ´ 10⁶/l was a marginal factor (P = 0.06) (Table 2). Multivariate analysis of DFS in 150 patients who achieved CR showed that age and karyotype were significant factors, whereas GSTT1^- was not significantly associated with a poor prognosis (P = 0.19, data not shown). The frequency of relapse at 50 months was similar in the GSTT1⁺ and GSTT1^- groups (53.2% vs 54.2%, P = 0.39 by the log-rank test, Figure 2).

To further analyze the significance of the GSTT1 polymorphism, clinical outcome was compared between the GSTT1⁺ and GSTT1^- groups (Table 3). The CR rate after initial induction therapy was lower in the GSTT1^- group than the GSTT1⁺ group, although the difference was not significant (66.7% vs 75.8%, P = 0.17). Since early death after initial chemotherapy is one of the factors worsening CR and overall survival rates, we studied how many patients died within 45, 60 and 120 days after the initiation of remission induction in each group. The rate of early death was higher than in the GSTT1^- group that GSTT1⁺ group (17.4% vs 8.9% within 45 days, P = 0.073; 20.3% vs 10.5% within 60 days, P = 0.054; 27.5% vs 13.7% within 120 days, P = 0.028). Bleeding and infection were common causes of early death in both groups. The GSTT1 genotype did not significantly affect the neutrophilic recovery after chemotherapy (data not shown). Notably, respiratory failure (n = 3) and cardiac arrhythmia (n = 1) occurred within 45 days only in the GSTT1^- group.

The GSTM1, NQO1 and MPO genotypes did not influence the prognosis (Figure 3, Table 2).

Discussion

GSTs are a family of enzymes that play an important role in detoxification by catalyzing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione.^13,14 Human GSTs are categorized into four main classes: alpha (A), mu (M), pi (P) and theta (T). Each class has a different substrate specificity. Among GST genes, GSTM1 and GSTT1 have null-allele variants that are commonly found in the population and result in a lack of enzyme activity.^15,16 A homozygous defect of GSTM1 or GSTT1 is associated with an increased risk of lung, breast and bladder cancers either alone or in combination with other intrinsic or environmental factors.^17,18,19 The GSTT1 null genotype was reported to increase the risk of myelodysplastic syndrome and acute leukemia,^7,20,21 although other studies failed to confirm these findings.^22,23

In this study, we showed that the GSTT1^- genotype was associated with a worse prognosis than the GSTT1⁺ genotype mainly due to increased early death after initial chemotherapy. Recently Davies et al²⁴ reported that in childhood AML, the GSTT1^- genotype was associated with a poor prognosis, and that the frequency of death in remission was increased by the GSTT1^- genotype. Our study, in adult patients with AML, essentially confirms this observation and further examined the reason why the GSTT1^- genotype worsened the prognosis. We noticed that CR, DFS, and relapse rates were not significantly different between the GSTT1⁺ and GSTT1^- groups. The rate of death among patients in remission was similar for the two genotypes (P = 0.25, by the ² test), which is in contrast to the previous paper.²⁴ Notably, the rate of early death was higher for the GSTT1^- genotype than the GSTT1⁺ genotype. Although the number of cases examined was limited, respiratory failure and cardiac arrhythmia were noted within 45 days only in the GSTT1^- group. Since the GSTT1 enzyme potentially metabolizes chemotherapeutic agents, both increased responsiveness and toxicity might be expected in the GSTT1^- group. Our study clearly indicated that the null genotype of GSTT1 was associated with increased toxicity of chemotherapy but not with a reduced rate of relapse. In malignancies other than leukemia, a GSTM1-null and GSTT1-null genotype was reportedly associated with poor prognosis due to unresponsiveness to primary chemotherapy,²⁵ as distinct from our finding. The significance of GST enzyme may be different in each malignancy and therapy.

It is unknown whether GSTT1 enzyme is actually involved in the metabolism of chemotherapeutic agents such as DNR, AraC and BHAC used in AML patients. According to the literature, carcinogens such as methyl chloride, mono-epoxybutane and di-epoxybutane are substrates for GSTT1.^26,27 Lymphocytes with the GSTT1^- genotype acquire chromosomal aberrations more sensitively than the GSTT1⁺ genotype when exposed to specific mutagenic substrates.^{18,28,29,30,31} Importantly, the increased expression of GST has been shown to be associated with resistance to a range of cytotoxic drugs, including alkylating agents,³² anthracyclines,³³ and nitrosoureas.³⁴ Glutathione (GSH)-related enzymes and the GSH-conjugate export pump are associated with cellular resistance to anti-cancer drugs.³⁵ However, the biological significance of GSTT1 enzyme among GST family is not fully elucidated. There are a number of polymorphic genes whose products are involved in drug metabolism that potentially influence outcome of chemotherapy. In this study, however, only GSTT1 genotype had an impact but not GSTM1, MPO and NQO1. A larger clinical study should be carried out to further confirm the significance of the GSTT1 genotype in addition to a biological study of the products.

In conclusion, we report evidence of individual differences of outcome after chemotherapy. To further improve chemotherapeutic outcome, a search for the genes influencing the outcome of anti-leukemia therapy is required and the dose/schedule of chemotherapy should be determined based on the individual differences using the gene polymorphisms.

Acknowledgements

This study was supported by a Grant-in Aid (No. 9-2) from the Japanese Ministry of Health and Welfare. We are grateful to members of the Japan Adult Leukemia Study Group for providing patients' samples. We also thank Ms Yoko Kudo for preparing the manuscript.

1 Appelbaum F. Molecular diagnosis and clinical decisions in adult acute leukemia. Semin Hematol 1999; 36: 401-410. MEDLINE

2 Lowenberg B, Downing J, Burnett A. Acute myeloid leukemia. N Engl J Med 1999; 341: 1051-1062. MEDLINE

3 Kiyoi H, Naoe T, Nakano Y, Yokota S, Minami S, Miyawaki S, Asou N, Kuriyama K, Jinnai I, Shimazaki C, Akiyama H, Saito K, Oh H, Motoji T, Omoto E, Saito H, Ohno R, Ueda R. Prognostic implication of FLT3 and N-RAS gene mutations in acute myeloid leukemia. Blood 1999; 93: 3074-3080. MEDLINE

4 Kiyoi H, Naoe T, Yokota S, Nakao M, Minami S, Kuriyama K, Takeshita A, Saito K, Hasegawa S, Shimodaira S, Tamura J, Shimazaki C, Matsue K, Kobayashi H, Arima N, Suzuki R, Morishita H, Saito H, Ueda R, Ohno R. Internal tandem duplication of FLT3 associated with leukocytosis in acute promyelocytic leukemia. Leukemia Study Group of the Ministry of Health and Welfare (Kohseisho). Leukemia 1997; 11: 1447-1452. MEDLINE

5 Baudard M, Beauchamp-Nicoud A, Delmer A, Rio B, Blanc C, Zittoun R, Marie JP. Has the prognosis of adult patients with acute myeloid leukemia improved over years? A single institution experience of 784 consecutive patients over a 16-year period. Leukemia 1999; 13: 1481-1490. MEDLINE

6 Boddy AV, Ratain MJ. Pharmacogenetics in cancer etiology and chemotherapy. Clin Cancer Res 1997; 3: 1025-1030. MEDLINE

7 Davies SM, Robison LL, Buckley JD, Radloff GA, Ross JA, Perentesis JP. Glutathione S-transferase polymorphisms in children with myeloid leukemia: a Children's Cancer Group study. Cancer Epidemiol Biomarkers Prev 2000; 9: 563-566. MEDLINE

8 Naoe T, Takeyama K, Yokozawa T, Kiyoi H, Seto M, Uike N, Ino T, Utsunomiya A, Maruta A, Jin-nai I, Kamada N, Kubota Y, Nakamura H, Shimazaki C, Horiike S, Kodera Y, Saito H, Ueda R, Wiemels J, Ohno R. Analysis of genetic polymorphism in NQO1, GST-M1, GST-T1 and CYP3A4 in 469 Japanese patients with therapy-related leukemia/myelodysplastic syndrome and de novo acute myeloid leukemia. Clin Cancer Res 2000; 6: 4091-4095. MEDLINE

9 Ohno R, Kobayashi T, Tanimoto M, Hiraoka A, Imai K, Asou N, Tomonaga M, Tsubaki K, Takahashi I, Kodera Y, Yoshida M, Murakami H, Naoe T, Shimayama M, Tsukada T, Takeo T, Teshima H, Onozawa Y, Fujimoto K, Kuriyama K, Horiuchi A, Kimura I, Minami S, Miura Y, Kageyama H, Tahara T, Masaoka T, Shirakawa S, Saito H. Randomized study of individualized induction therapy with or without vincristine, and of maintenance-intensification therapy between 4 or 12 courses in adult acute myeloid leukemia. AML-87 Study of the Japan Adult Leukemia Study Group. Cancer 1993; 71: 3888-3895. MEDLINE

10 Kobayashi T, Miyawaki S, Tanimoto M, Kuriyama K, Murakami H, Yoshida M, Minami S, Minato K, Tsubaki K, Ohmoto E, Oh H, Jinnai I, Sakamaki H, Hiraoka A, Kanamaru A, Takahashi I, Saito K, Naoe T, Yamada O, Asou N, Kageyama S, Emi N, Matsuoka A, Tomonaga M, Ohno R and for the Japan Adult Leukemia Study Group. Randomized trials between behenoyl cytarabine and cytarabine in combination induction and consolidation therapy, and with or without ubenimex after maintenance/intensification therapy in adult acute myeloid leukemia. The Japan Leukemia Study Group. J Clin Oncol 1996; 14: 204-213. MEDLINE

11 Miyawaki S, Tanimoto M, Kobayashi T, Minami S, Tamura J, Omoto E, Kuriyama K, Hatake K, Saito K, Kanamaru A, Oh H, Ohtake S, Asou N, Sakamaki H, Yamada O, Jinnai I, Tsubaki K, Takeyama K, Hiraoka A, Matsuda S, Takahashi M, Shimazaki C, Adachi K, Kageyama S, Ohno R and for the Japan Adult Leukemia Study Group. No beneficial effect from addition of etoposide to daunorubicin, cytarabine, and 6-mercaptopurine in individualized induction therapy of adult acute myeloid leukemia: the JALSG-AML92 study. Japan Adult Leukemia Study Group. Int J Hematol 1999; 70: 97-104. MEDLINE

12 Cascorbi I, Henning S, Brockmoller J, Gephart J, Meisel C, Muller JM, Loddenkemper R, Roots I. Substantially reduced risk of cancer of the aerodigestive tract in subjects with variant-463A of the myeloperoxidase gene. Cancer Res 2000; 60: 644-649. MEDLINE

13 Wilce M, Parker M. Structure and function of glutathione S-transferases. Biochim Biophys Acta 1994; 1205: 1-18. MEDLINE

14 Hayes J, Pulford D. The glutathione S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance. Crit Rev Biochem Mol Biol 1995; 30: 445-600. MEDLINE

15 Board PG. Biochemical genetics of glutathione-S-transferase in man. Am J Hum Genet 1981; 33: 36-43. MEDLINE

16 Pemble S, Schroeder KR, Spencer SR, Meyer DJ, Hallier E, Bolt HM, Ketterer B, Taylor JB. Human glutathione S-transferase theta (GSTT1): cDNA cloning and the characterization of a genetic polymorphism. Biochem J 1994; 300: 271-276. MEDLINE

17 Rebbeck T. Molecular epidemiology of the human glutathione S-transferase genotypes GSTM1 and GSTT1 in cancer susceptibility. Cancer Epidemiol Biomarkers Prev 1997; 6: 733-743. MEDLINE

18 Hengstler JG, Arand M, Herrero ME, Oesch F. Polymorphisms of N-acetyltransferases, glutathione S-transferases, microsomal epoxide hydrolase and sulfotransferases: influence on cancer susceptibility. Rec Res Cancer Res 1998; 154: 47-85.

19 Strange R, Fryer A. The glutathione S-transferases: influence of polymorphism on cancer susceptibility. IARC Sci Publ 1999; 148: 231-249. MEDLINE

20 Chen CL, Liu Q, Pui CH, Rivera GK, Sandlund JT, Ribeiro R, Evans WE, Relling MV. Higher frequency of glutathione S-transferase deletions in black children with acute lymphoblastic leukemia. Blood 1997; 89: 1701-1707. MEDLINE

21 Chen H, Sandler DP, Taylor JA, Shore DL, Liu E, Bloomfield CD, Bell DA. Increased risk for myelodysplastic syndromes in individuals with glutathione transferase theta 1 (GSTT1) gene defect. Lancet 1996; 347: 295-297. MEDLINE

22 Preudhomme C, Nisse C, Hebbar M, Vanrumbeke M, Brizard A, Lai JL, Fenaux P. Glutathione S transferase theta 1 gene defects in myelodysplastic syndromes and their correlation with karyotype and exposure to potential carcinogens. Leukemia 1997; 11: 1580-1582. MEDLINE

23 Crump C, Chen C, Appelbaum FR, Kopecky KJ, Schwartz SM, Willman CL, Slovak ML, Weiss NS. Glutathione S-transferase theta 1 gene deletion and risk of acute myeloid leukemia. Cancer Epidemiol Biomarkers Prev 2000; 9: 457-460. MEDLINE

24 Davies SM, Robison LL, Buckley JD, Tjoa T, Woods WG, Radloff GA, Ross JA, Perentesis JP. Glutathione S-transferase polymorphisms and outcome of chemotherapy in childhood acute myeloid leukemia. J Clin Oncol 2001; 19: 1279-1287. MEDLINE

25 Howells RE, Redman CW, Dhar KK, Sarhanis P, Musgrove C, Jones PW, Alldersea J, Fryer AA, Hoban PR, Strange RC. Association of glutathione S-transferase GSTM1 and GSTT1 null genotypes with clinical outcome in epithelial ovarian cancer. Clin Cancer Res 1998; 4: 2439-2445. MEDLINE

26 Russo J, Russo I. Biological and molecular bases of mammary carcinogenesis. Lab Invest 1987; 57: 112-137. MEDLINE

27 Wiencke J, Pemble S, Ketterer B, Kelsey K. Gene deletion ofglutathione S-transferase theta: correlation with induced genetic damage and potential role in endogenous mutagenesis. Cancer Epidemiol Biomarkers Prev 1995; 4: 253-259. MEDLINE

28 Kelsey KT, Wiencke JK, Ward J, Bechtold W, Fajen J. Sister-chromatid exchanges, glutathione S-transferase theta deletion and cytogenetic sensitivity to diepoxybutane in lymphocytes from butadiene monomer production workers. Mutat Res 1995; 335: 267-273. MEDLINE

29 Norppa H, Hirvonen A, Jarventaus H, Uuskula M, Tasa G, Ojajarvi A, Sorsa M. Role of GSTT1 and GSTM1 genotypes in determining individual sensitivity to sister chromatid exchange induction by diepoxybutane in cultured human lymphocytes. Carcinogenesis 1995; 16: 1261-1264. MEDLINE

30 Pelin K, Hirvonen A, Norppa H. Influence of erythrocyte glutathione S-transferase T1 on sister chromatid exchanges induced by diepoxybutane in cultured human lymphocytes. Mutagenesis 1996; 11: 213-215. MEDLINE

31 Xu X, Wiencke JK, Niu T, Wang M, Watanabe H, Kelsey KT, Christiani DC. Benzene exposure, glutathione S-transferase theta homozygous deletion, and sister chromatid exchanges. Am J Ind Med 1998; 33: 157-163. Article MEDLINE

32 Hoban PR, Robson CN, Davies SM, Hall AG, Cattan AR, Hickson ID, Harris AL. Reduced topoisomerase II and elevated alpha class glutathione S-transferase expression in a multidrug resistant CHO cell line highly cross-resistant to mitomycin C. Biochem Pharmacol 1992; 43: 685-693. MEDLINE

33 Chao CC, Huang YT, Ma CM, Chou WY, Lin-Chao S. Overexpression of glutathione S-transferase and elevation of thiol pools in a multidrug-resistant human colon cancer cell line. Mol Pharmacol 1992; 41: 69-75. MEDLINE

34 Smith MT, Evans CG, Doane-Setzer P, Castro VM, Tahir MK, Mannervik B. Denitrosation of 1,3-bis(2-chloroethyl)-1-nitrosourea by class mu glutathione transferases and its role in cellular resistance in rat brain tumor cells. Cancer Res 1989; 49: 2621-2625. MEDLINE

35 Loe DW, Stewart RK, Massey TE, Deeley RG, Cole SP. ATP-dependent transport of aflatoxin B1 and its glutathione conjugates by the product of the multidrug resistance protein (MRP) gene. Mol Pharmacol 1997; 51: 1034-1041. MEDLINE

Figure 1 Kaplan-Meier curves of overall survival and DFS according to GSTT1 genotype. The GSTT1^- group (n = 69) had a worse overall survival than the GSTT⁺ group (n = 124). The predicted overall survival rates at 50 months were 33.7% and 22.1% in the GSTT1⁺ and GSTT1^- groups, respectively. DFS in 140 patients who achieved CR did not differ between GSTT1⁺ (n = 94) and GSTT1^- (n = 46) groups (P = 0.22).

Figure 2 Accumulation curves of relapse according to GSTT1 genotype. The frequency of relapse at 50 months was similar in the GSTT1⁺ and GSTT1^- groups (53.2% vs 54.2%, P = 0.39 by the log-rank test).

Figure 3 Kaplan-Meier curves of overall survival according to GSTM1, NQO1 and MPO genotypes.

Table 1 Clinical and molecular characteristics of 193 patients with de novo AML except M3 according to GSTT1 genotype

Table 2 Unfavorable prognostic factors for overall survival in 193 patients with de novo AML

Table 3 Clinical outcome of 193 patients with de novo AML except M3 after induction therapy