BU is a key compound of conditioning regimens in children undergoing hematopoietic SCT (HSCT). Inter-individual differences in BU pharmacokinetics (PKs) might affect BU efficacy and toxicity. As BU is mainly metabolized by glutathione S-transferase (GST), we investigated the relationship between GSTA1, GSTM1 and GSTP1 genotypes with first-dose BU PKs, and the relationship with HSCT outcomes in 69 children receiving myeloablative conditioning regimen. GSTM1 null genotype correlated with higher BU exposure and lower clearance in patients older than 4 years (P⩽0.04). In accordance with the suggested functional role, GSTA1*A2 haplotype was associated with lower drug levels and higher drug clearance (P⩽0.03). Gene-dosage effect was also observed (P⩽0.007). GSTA1 haplotypes were associated with HSCT outcomes. Patients with two copies of haplotype *A2 had better event free survival (P=0.03). In contrast, homozygous individuals for haplotypes *B and *B1 had higher occurrence of veno-occlusive disease (P=0.009). GSTM1 null individuals older than 4 years had more frequently graft versus host disease (P=0.03). In conclusion, we showed that GST gene variants influence BU PK and outcomes of HSCT in children. A model for the dosage adjustment with the inclusion of genetic and non-genetic factors should be evaluated in a future prospective validation cohort.
BU is a key component of myeloablative regimens given before hematopoietic SCT (HSCT).1 Inter-individual variation in BU plasma levels is observed even when BU is administered by the i.v. route.2, 3 There is no consensus on the optimal therapeutic window of i.v. BU in pediatric patients; although studies have shown improved outcomes at steady-state concentrations (Css) of 600–900 ng/mL, when a conventional dosing schedule is followed.3, 4, 5, 6 There is an increased incidence of adverse events such as veno-occlusive disease (VOD), pulmonary toxicity and graft versus host disease (GVHD) at higher concentrations and graft failure or disease relapse at lower concentrations in pediatric and adult patients.4, 7, 8 To decrease the occurrence of toxicity and to improve efficacy, therapeutic drug monitoring is performed to adjust BU dose based on the first-dose pharmacokinetics (PKs).6, 8 In addition to the PK-guided dosing of BU, prediction of inter-individual variability in BU levels before its administration would be helpful in individualizing BU treatment.
BU is primarily metabolized by liver glutathione S-transferase enzymes (GST), predominantly by GSTA1.9, 10 GSTM1 and GSTP1 are also involved in BU metabolism but to a lesser extent.9, 11 BU metabolism is affected by GST enzyme activity, which is influenced by age, disease condition and co-medication.2, 12, 13, 14 Body weight and body surface area have been also shown to contribute to PK variability.15, 16, 17, 18, 19 Nevertheless, a large proportion of BU variability remains unexplained20 and could be due to GST polymorphisms influencing GST activity21, 22, 23, 24, 25 (Table 1). Although some studies have shown that GSTA1 genotypes influence the PK of oral and i.v. BU in both adults and children;17, 26, 27, 28, 29, 30 others did not find this association.15, 31, 32 In a small pilot study, we have shown that polymorphisms in GSTM1 might influence the PK of BU.15 The present work was undertaken to confirm this finding and to allow more detailed insight into GST variants in a larger cohort.
Materials and methods
This study comprises 69 consecutive patients (including 28 from earlier study15; 32 men, 37 women, median age 6.5) who underwent allogeneic HSCT with i.v. BU at CHU Sainte-Justine, between May 2000 and August 2010. The review board approved the study and all patients/parents provided informed consent. The demographic characteristics of the patients, details of disease and transplantation are given in Table 2.
I.v. BU (Busulfex, Otsuka Pharmaceuticals, Saint-Laurent, Montreal, QC, Canada). was administered as a 2-h infusion every 6 h from day −9 to −6. BU first dose was based on the age of the patient (infants⩾3 months and 1 year of age and children⩾4 years old received 0.8 mg/kg dose, children⩾1 year and 4 years old received 1 mg/kg dose) and PK-guided dose adjustment was performed from the fifth dose onward.15 All the patients received 16 doses of BU followed by, i.v. CY (200 mg/kg total dose; n=62; Table 2). Cyclosporine was given as GVHD prophylaxis, and MTX or steroids were added for BM/peripheral blood and cord blood transplantation, respectively (Table 2). G-CSF was used after cord blood transplantation only. Prophylaxis for seizure included midazolam lorazepam or phenytoin. Fluconazole, acyclovir and trimethoprim/sulfamethoxazole were given as anti-infectious prophylaxis and acid ursodeoxycholic as VOD prophylaxis.
Definition of clinical outcomes
Diagnostic criteria for adverse events are detailed elsewhere.15 In brief, VOD was diagnosed according to the Seattle criteria33 and acute (a)GVHD was based on the 1994 Consensus Conference.34 Neutrophil and platelet recoveries were defined as absolute count ⩾0.5 × 109/L for the first 3 consecutive days and ⩾50 × 109/L without transfusion for the first 10 consecutive days from the day of transplant, respectively. Overall survival (OS) was the time between day of transplant and death because of any cause, whereas event free survival (EFS) was the time from day of transplant to the day of occurrence of any event that is, death, relapse or graft failure, whichever is seen first. OS was 83% at 1 year and EFS was 69% at 1 year. Details are also provided in the Table 3a.
PK analysis and genotyping
Five blood samples were collected after the first-dose infusion and were used for estimation of BU levels using an established analytical method.35 The PK parameters were estimated from the first dose using non-compartmental analysis (WinNonlin, version 3.1, Pharsight, Montreal, QC, Canada) and further doses from fifth dose onward were adjusted to achieve BU Css of 600–900 ng/mL. PK data are represented in terms of maximum concentration (Cmax), area under the curve (AUC), Css and clearance (CL; Table 3b).
BU PK parameters (Cmax, AUC, Css and CL) and dose adjustment were compared across genotypes of GSTA1, GSTP1 and GSTM1 or between carriers and non-carriers of particular GSTA1 haplotype subtypes using non-parametric tests. Depending on the results obtained, appropriate genetic models (dominant, recessive or additive) for particular genotypes–haplotypes were subsequently derived. Non-parametric or χ2-tests were used to test differences in gender and age between different genotype groups. Linear regression was used to test gene-dosage effect and to assess the effect of genotypes on Cmax, AUC, Css and CL in a multivariate model with the inclusion of other covariates (age, gender, weight and BU dose). Survival (OS and EFS) was estimated using Kaplan–Meier curves and log-rank test was used to compare the differences between genotype groups in univariate analysis. EFS analysis for particular genotype was also performed when the event and follow-up were truncated to 1-year post HSCT. The cumulative incidence of engraftment or HSCT-related toxicity (VOD, aGVHD grades 1–4, lung toxicity, hemorrhagic cystitis, or any of these toxicities, whichever was seen first) in relation to the GST genotypes was estimated by one-survival curves using Kaplan–Meier analysis and log-rank test. Frequency of all toxic events between particular genotype groups was compared by χ2-test. Univariate Cox regression analysis was used to estimate hazard ratio (HR) with 95% confidence interval (CI); multivariate Cox regression was used to estimate the impact of genotypes on clinical outcomes in the presence of other covariates (same as above). Logistic regression was used to estimate percentage of variability in clinical outcomes because of genetic/non-genetic factors. Kaplan–Meier functions were used to assess relationship between PK data (categorical variable with four different categories corresponding to quartile distribution) and clinical outcomes. All PK parameters showed similar results; Css is used to present the data. Haplotypes were resolved using PHASE (version 2.1).37 Statistical analyses were performed using IBM SPSS statistics (version 19, SPSS Inc., New York, NY, USA).
Genetic variants of GSTA1, M1, P1 and BU PKs
The GSTA1*A and *B haplotypes, defined by the −69C>T substitution, are further subdivided based on the presence or absence of minor alleles at positions –631, −1142 and −531 (Table 4). No significant association of GSTA1 genotypes with BU PK was observed when each GSTA1 polymorphism was analyzed individually. However, when haplotype-based analysis was performed, significant differences (P⩽0.03) for each PK parameter analyzed (Cmax, Css, AUC and CL) was noted between the carriers and non-carriers of GSTA1*A2 haplotype (Figure 1a). Carriers had significantly lower AUC, Cmax and Css and higher CL compared with non-carriers. Similar differences were seen between two groups when the PK parameters (Cmax, Css and AUC) were normalized with BU first dose (mg/kg, P⩽0.03, data not shown). The gene-dose effect of GSTA1*A2 haplotype was also observed (Figure 1b). Decrease in BU levels represented by Css (P=0.007) and increase in CL (P=0.005) correlated with the number of GSTA1*A2 haplotypes, being highest in individuals homozygous for that haplotype. No other GSTA1 haplotype correlated with BU PK.
BU levels adjusted by dose (mg/kg) differed significantly (P⩽0.001, data not shown) between individuals below (n=26) and above 4 years of age (n=43), suggesting the influence of age along with the genetic parameters studied. Similarly, Cmax distribution differed between males and females (P=0.04, data not shown). This prompted us to further investigate the association between GST genotype and BU PK on stratification by gender or age. In accordance with our previous report,15 GSTM1 association with PK was apparent in individuals above 4 years of age receiving uniform BU dose (0.8 mg/kg). The patients with GSTM1 null genotype had higher Cmax (P=0.02), and lower CL (P=0.04) compared with those with non-null genotype. A trend was observed for Css (P=0.07) and AUC (P=0.06), with null individuals having higher values compared with non-null individuals (Figure 2). The association of GSTA1 haplotype *A2 was particularly apparent in females (Supplementary Figure 1). No age-dependent correlation between PK and GSTA1 genotypes or gender-dependent GSTM1-PK correlation was noted. Finally, no correlation between GSTM1 and GSTA*A2 genotypes and age or gender of patients was seen.
In a multivariate regression model that included age, gender, BU dose and weight as covariates, genotypes remained associated with BU PK (CL, P=0.03 for GSTA1*A2 and 0.04 for GSTM1 null; Css, P=0.04 for both genotypes; AUC, P=0.02 for both genotypes; Cmax, P=0.01 for GSTA1*A2 and 0.007 for GSTM1 null). The model with both genotypes and non-genetic covariates explained 47–54% of variability in PK with genetic factors contributing to 14–17% of this variability.
The ratio of adjusted dose to initial dose was used to compare the increment or decrement of dose according to genotype. GSTM1 null individuals received lower BU dose compared with GSTM1 non-null individuals (P=0.03; Figure 3a). Patients who are homozygous for GSTA*A2 haplotype had a higher increase in dose compared with remaining individuals (P=0.02, Figure 3a). In spite of dose adjustment, Css after eighth dose (available for 50 patients), although within the target range, was still significantly lower in *A2 carriers, compared with non-carriers (P=0.007, Figure 3b). No such relationship was seen for GSTM1 genotype. No correlation between GSTP1 genotypes and PK was observed.
Genetic variants of GSTA1, M1, P1 and clinical outcomes of HSCT
Details of clinical outcomes are given in Table 3a. Patients with two copies of haplotype GSTA1*A2 had better EFS (100% vs 54%, P=0.03, Figure 4a). No event occurred in *A2 homozygotes (n=8), whereas events occurred in 26 out of the remaining 61 individuals. Gene-dosage effect was seen for EFS only at 1 year after HSCT (P=0.03, data not shown). Reduction of toxicity was observed in *A2 homozygotes; only one patient had VOD and none had hemorrhagic cystitis, lung toxicity or aGVHD (P=0.01 for number of all toxic events combined and P=0.06 for cumulative incidence of any toxicity). To verify whether these associations are due to *A2–PK relationship, we analyzed an association between Css and EFS and between Css and toxic events. Similar to our previous study,38 lower Css was associated with better EFS (P<0.0005, data not shown); higher Css correlated with higher cumulative incidence of any toxicity (P=0.005, data not shown) and with each individual toxicity (aGVHD, lung toxicity and hemorrhagic cystitis, P⩽0.03) except VOD.
Association analyses between GST genotypes and HSCT-related toxicities indicated that homozygous GSTA1 −69 TT and −1142 GG patients had higher occurrence of VOD. As shown in Table 4, the T allele of −69C>T defines haplotype *B (all haplotypes *B combined) and G allele of −1142C>G defines haplotype *B1, therefore the same results are obtained with these haplotypes. VOD was seen in 43% homozygous *B or *B1 individuals compared with 9.6% in remaining patients (HR=5.3, 95% CI= 1.3–21.5, P=0.009; Figure 4b). The effect seems to be modulated by gender, being more apparent in girls than in boys (75% vs 12.5%, HR=9.6; 95% CI=2.0–45.1, P=0.001; Figure 4c). GSTM1 null individual above age of 4 had more frequently aGVHD (grades 1–4, 44% vs 17%, HR=3.8, 95% CI=1.1–13.7, P=0.03; Figure 4d). Genotypes remained significantly associated with clinical outcomes in multivariate models that included age, gender, BU dose and weight as covariates. Genetic and non-genetic factors explained 26% of EFS variability (with 11% of GSTA1*A2 contribution, P=0.05), 26% of VOD variability (with 19% of GSTA1*B contribution, P=0.04) and 32% of aGVHD variability (with 10% of GSTM1 null contribution). No other significant association between GST genotypes–haplotypes and HSCT clinical outcomes was seen.
GST genetic variants and BU PK variability
Analysis of GSTA1 genotypes–haplotypes revealed significant associations with BU exposure. An increase in BU CL and reduction in drug levels following the first dose was seen in individuals with GSTA1*A2 haplotype. Gene-dosage effect was also noted. Our observation is in accordance with the functional studies suggesting higher GSTA activity in GSTA1*A carriers10, 22, 24 and is also supported by several previous reports.17, 26, 27, 28, 29, 30 Decreased CL following oral BU was seen in adults and children with GSTA*B haplotype;17, 29, 31 a significant decrease in CL following i.v. BU was observed in pediatric GSTA1*B patients;21, 22 and accordingly increased BU CL correlated with GSTA1*A haplotype.17, 39 However, a few studies conducted in adults and children15, 31, 32 failed to show such an association, which might be due to low sample size,15 different BU dosing schedules,31, 32 dose adjustment, or varying proportions of non-malignant diseases.15, 31, 32 Use of phenytoin31 or different methods of estimating BU PK might also have contributed to the conflicting observations. Our study included patients receiving only myeloablative conditioning regimen with i.v. BU in a conventional dosing schedule with a small proportion of hemoglobinopathy (<15%) and only three patients that received phenytoin for seizure prevention. Patients were also categorized into specific subtypes of GSTA1*A/*B haplotypes allowing more detailed insight into the GSTA1 gene effect. We also noted a gender-dependent effect of GSTA1 genotype. GSTA1*A haplotype influence on BU metabolism might be more prominent in females as they were shown to have lower cytosolic GST activity compared with males.40
We confirmed our previous findings on association of GSTM1 genotypes with BU exposure.15 GSTM1 null genotypes were significantly associated with higher BU levels and lower BU CL in individuals older than 4 years, which can be explained, to a certain extent, by increased GSTM1 involvement of BU metabolism in older children with moderate or reduced GSTA activity.6 Observations from our study are not in agreement with a report by Srivastava et al.,41 who showed enhanced CL and low Css of oral BU in thalassemia children carrying GSTM1 null genotype. Another study conducted in adult patients found reduced i.v. BU CL in individuals with combined GSTM1 and GSTT1 null genotypes, but not in individuals with GSTM1 null genotype alone,39 whereas others reported absence of such association.17, 26, 27, 30, 31, 32 The compensatory action of other GST isoforms to defective enzyme activity has been also demonstrated.39 We did not find clear combined effect or interaction between GSTM1 and GSTA1 genotypes. However, it is worth noting that the distribution of the genotypes was not completely random. All individuals that were GSTA*A2 carriers also had GSTM1 non-null genotype, that is, there was no individuals that had GSTA*A2 and GSTM1 null genotype combination; hence the combined GSTA1/GSTM1 effect cannot be ruled out.
Multiple linear regression analysis showed that genetic factors contribute to 14–17% of the variability in BU PK compared with non-genetic factors alone (∼30%). This is similar to studies conducted in adults that have reported that GSTA1 polymorphisms could account for 15–18% of the variability in first-dose BU CL, and in line with the unexplained variability of BU CL among pediatric patients reported in a recent meta-analysis.16, 30, 39
Homozygous GSTA1*A2 individuals had an augmentation of BU dose, owing to increased CL of BU. Although reaching the target level, *A2 carriers had still lower Css after the eighth dose as compared with non-carriers, which may suggest the need to reduce the BU dose in patient without *A2 haplotype. Wide ranges in the requirement of BU dose was nevertheless seen in individuals with no GSTA1*A2 homozygosity, which might be due to age, presence of single GSTA1*A2 copy, GSTM1 or other genotypes. GSTM1 null individuals had subsequently received lower BU doses than non-null individuals explained by lower CL in GSTM1 null patients.
GST genetic variants and clinical outcomes of HSCT
Better EFS was seen in homozygous GSTA1*A2 patients, which is likely due to a significantly lower BU levels seen in these individuals. Indeed, lower Css correlated with better EFS, which is in accordance with our observation38 and with previous reports.19 It is worth noting that Css in GSTA1*A2 carriers following dose adjustment, was on average in the target range but did not exceed the target concentrations and was significantly lower than in individuals without this haplotype, which might resulted in lower toxicity. Indeed, overall reduction in toxicity was noted for homozygous GSTA1*A2 patients, further supported by correlation between lower Css and less frequent toxicity. This finding might support previous observation of decreased incidence of GVHD in GSTA1*A/*A patients.28
We have also shown that individuals that are homozygous for either haplotype *B or *B1, respectively, had higher incidence of VOD. Haplotype *B was reported to confer decreased GSTA1 activity,22 suggesting higher BU level in such individuals. Higher AUC levels were indeed reported to correlate with VOD.42 We have not, however, found either significant association between Css and VOD or between *B (*B1) haplotype and PK, which can be due to low VOD and/or genotype numbers, but also involvement of BU-independent mechanism. For example, liver toxicity could be influenced by CY, including time of its administration relative to BU.43, 44 Higher levels of toxic metabolites of CY in GSTA*B homozygotes can also contribute to VOD development, in which case administration of CY after BU would be detrimental. This finding is nevertheless contrary to the hypothesis that increased activity of GSTA in GSTM1 null individuals might deplete GSH causing damage to liver and occurrence of VOD.41 None of the few studies that looked into an association between GST genotypes and clinical outcomes17, 28, 32 reported correlation between GSTA1 genotypes and EFS or VOD, which may be due to the low incidence of VOD, inclusion of patients on non-myeloablative regimen, other events, non-investigated factors that may potentiate GSTA1 effect (for example, gender), dose adjustment or low sample size. We did not observe any association of VOD with GSTM1 genotypes, in agreement with previous studies15, 17, 28 and contrary to a report on higher VOD incidence in GSTM1 null carriers, which could be attributed to the different patient population.41 And finally, our finding of higher GVHD frequency in GSTM1 null individuals in agreement with previous report.17. This could be explained by observed GSTM1 null–PK relationship, further supported by an association between higher Css and higher incidence of aGVHD.
In conclusion, we showed that GST gene variants influence BU PK and outcomes of HSCT in children. A model for the dosage adjustment with the inclusion of genetic and non-genetic factors should be evaluated in a future prospective validation cohort. Predicting BU dose before initiation of therapy will be helpful to achieve better clinical outcomes in pediatric patients and pave the way for individualized BU treatment according to the individual patient’s genetic profile.
Slattery JT, Clift RA, Buckner CD, Radich J, Storer B, Bensinger WI et al. Marrow transplantation for chronic myeloid leukemia: the influence of plasma busulfan levels on the outcome of transplantation. Blood 1997; 89: 3055–3060.
Dalle JH, Wall D, Theoret Y, Duval M, Shaw L, Larocque D et al. Intravenous busulfan for allogeneic hematopoietic stem cell transplantation in infants: clinical and pharmacokinetic results. Bone Marrow Transplant 2003; 32: 647–651.
Tran H, Petropoulos D, Worth L, Mullen CA, Madden T, Andersson B et al. Pharmacokinetics and individualized dose adjustment of intravenous busulfan in children with advanced hematologic malignancies undergoing allogeneic stem cell transplantation. Biol Blood Marrow Transplant 2004; 10: 805–812.
Vassal G, Michel G, Esperou H, Gentet JC, Valteau-Couanet D, Doz F et al. Prospective validation of a novel IV busulfan fixed dosing for paediatric patients to improve therapeutic AUC targeting without drug monitoring. Cancer Chemother Pharmacol 2008; 61: 113–123.
Bolinger AM, Zangwill AB, Slattery JT, Risler LJ, Sultan DH, Glidden DV et al. Target dose adjustment of busulfan in pediatric patients undergoing bone marrow transplantation. Bone Marrow Transplant 2001; 28: 1013–1018.
McCune JS, Gibbs JP, Slattery JT . Plasma concentration monitoring of busulfan: does it improve clinical outcome? Clin Pharmacokinet 2000; 39: 155–165.
Andersson BS, Thall PF, Madden T, Couriel D, Wang X, Tran HT et al. Busulfan systemic exposure relative to regimen-related toxicity and acute graft-versus-host disease: defining a therapeutic window for i.v. BuCy2 in chronic myelogenous leukemia. Biol Blood Marrow Transplant 2002; 8: 477–485.
Malar R, Sjoo F, Rentsch K, Hassan M, Gungor T . Therapeutic drug monitoring is essential for intravenous busulfan therapy in pediatric hematopoietic stem cell recipients. Pediatr Transplant 2011; 15: 580–588.
Rowe JD, Nieves E, Listowsky I . Subunit diversity and tissue distribution of human glutathione S-transferases: interpretations based on electrospray ionization-MS and peptide sequence-specific antisera. Biochem J 1997; 325 (Part 2): 481–486.
Cooper AJ, Younis IR, Niatsetskaya ZV, Krasnikov BF, Pinto JT, Petros WP et al. Metabolism of the cysteine S-conjugate of busulfan involves a beta-lyase reaction. Drug Metab Dispos 2008; 36: 1546–1552.
Czerwinski M, Gibbs JP, Slattery JT . Busulfan conjugation by glutathione S-transferases alpha, mu, and pi. Drug Metab Dispos 1996; 24: 1015–1019.
Gulbis AM, Culotta KS, Jones RB, Andersson BS . Busulfan and metronidazole: an often forgotten but significant drug interaction. Ann Pharmacother 2011; 45: e39.
Nath CE, Earl JW, Pati N, Stephen K, Shaw PJ . Variability in the pharmacokinetics of intravenous busulphan given as a single daily dose to paediatric blood or marrow transplant recipients. Br J Clin Pharmacol 2008; 66: 50–59.
Schechter T, Finkelstein Y, Doyle J, Verjee Z, Moretti M, Koren G et al. Pharmacokinetic disposition and clinical outcomes in infants and children receiving intravenous busulfan for allogeneic hematopoietic stem cell transplantation. Biol Blood Marrow Transplant 2007; 13: 307–314.
Ansari M, Lauzon-Joset JF, Vachon MF, Duval M, Theoret Y, Champagne MA et al. Influence of GST gene polymorphisms on busulfan pharmacokinetics in children. Bone Marrow Transplant 2010; 45: 261–267.
Bartelink IH, Boelens JJ, Bredius RG, Egberts AC, Wang C, Bierings MB et al. Body weight-dependent pharmacokinetics of busulfan in paediatric haematopoietic stem cell transplantation patients: towards individualized dosing. Clin Pharmacokinet 2012; 51: 331–345.
Elhasid R, Krivoy N, Rowe JM, Sprecher E, Adler L, Elkin H et al. Influence of glutathione S-transferase A1, P1, M1, T1 polymorphisms on oral busulfan pharmacokinetics in children with congenital hemoglobinopathies undergoing hematopoietic stem cell transplantation. Pediatr Blood Cancer 2010; 55: 1172–1179.
Paci A, Vassal G, Moshous D, Dalle JH, Bleyzac N, Neven B et al. Pharmacokinetic behavior and appraisal of intravenous busulfan dosing in infants and older children: the results of a population pharmacokinetic study from a large pediatric cohort undergoing hematopoietic stem-cell transplantation. Ther Drug Monit 2012; 34: 198–208.
Bartelink IH, Bredius RG, Belitser SV, Suttorp MM, Bierings M, Knibbe CA et al. Association between busulfan exposure and outcome in children receiving intravenous busulfan before hematologic stem cell transplantation. Biol Blood Marrow Transplant 2009; 15: 231–241.
Ansari M, Krajinovic M . Can the pharmacogenetics of GST gene polymorphisms predict the dose of busulfan in pediatric hematopoietic stem cell transplantation? Pharmacogenomics 2009; 10: 1729–1732.
Bredschneider M, Klein K, Murdter TE, Marx C, Eichelbaum M, Nussler AK et al. Genetic polymorphisms of glutathione S-transferase A1, the major glutathione S-transferase in human liver: consequences for enzyme expression and busulfan conjugation. Clin Pharmacol Ther 2002; 71: 479–487.
Coles BF, Morel F, Rauch C, Huber WW, Yang M, Teitel CH et al. Effect of polymorphism in the human glutathione S-transferase A1 promoter on hepatic GSTA1 and GSTA2 expression. Pharmacogenetics 2001; 11: 663–669.
Di Pietro G, Magno LA, Rios-Santos F . Glutathione S-transferases: an overview in cancer research. Expert Opin Drug Metab Toxicol 2010; 6: 153–170.
Ning B, Wang C, Morel F, Nowell S, Ratnasinghe DL, Carter W et al. Human glutathione S-transferase A2 polymorphisms: variant expression, distribution in prostate cancer cases/controls and a novel form. Pharmacogenetics 2004; 14: 35–44.
Reszka E, Jablonowski Z, Wieczorek E, Gromadzinska J, Sosnowski M, Wasowicz W . GSTP1 mRNA expression in human circulating blood leukocytes is associated with GSTP1 genetic polymorphism. Clin Biochem 2011; 44: 1153–1155.
Gaziev J, Nguyen L, Puozzo C, Mozzi AF, Casella M, Perrone DM et al. Novel pharmacokinetic behavior of intravenous busulfan in children with thalassemia undergoing hematopoietic stem cell transplantation: a prospective evaluation of pharmacokinetic and pharmacodynamic profile with therapeutic drug monitoring. Blood 2010; 115: 4597–4604.
Johnson L, Orchard PJ, Baker KS, Brundage R, Cao Q, Wang X et al. Glutathione S-transferase A1 genetic variants reduce busulfan clearance in children undergoing hematopoietic cell transplantation. J Clin Pharmacol 2008; 48: 1052–1062.
Kim I, Keam B, Lee KH, Kim JH, Oh SY, Ra EK et al. Glutathione S-transferase A1 polymorphisms and acute graft-vs.-host disease in HLA-matched sibling allogeneic hematopoietic stem cell transplantation. Clin Transplant 2007; 21: 207–213.
Kusama M, Kubota T, Matsukura Y, Matsuno K, Ogawa S, Kanda Y et al. Influence of glutathione S-transferase A1 polymorphism on the pharmacokinetics of busulfan. Clin Chim Acta 2006; 368: 93–98.
ten Brink MH, Wessels JA, den Hartigh J, van der Straaten T, von dem Borne PA, Guchelaar HJ et al. Effect of genetic polymorphisms in genes encoding GST isoenzymes on BU pharmacokinetics in adult patients undergoing hematopoietic SCT. Bone Marrow Transplant 2012; 47: 190–195.
Abbasi N, Vadnais B, Knutson JA, Blough DK, Kelly EJ, O’Donnell PV et al. Pharmacogenetics of intravenous and oral busulfan in hematopoietic cell transplant recipients. J Clin Pharmacol 2011; 51: 1429–1438.
Zwaveling J, Press RR, Bredius RG, van Derstraaten TR, den Hartigh J, Bartelink IH et al. Glutathione S-transferase polymorphisms are not associated with population pharmacokinetic parameters of busulfan in pediatric patients. Ther Drug Monit 2008; 30: 504–510.
Przepiorka D, Weisdorf D, Martin P, Klingemann HG, Beatty P, Hows J et al. 1994 Consensus conference on acute GVHD grading. Bone Marrow Transplant 1995; 15: 825–828.
McDonald GB, Hinds MS, Fisher LD, Schoch HG, Wolford JL, Banaji M et al. Veno-occlusive disease of the liver and multiorgan failure after bone marrow transplantation: a cohort study of 355 patients. Ann Intern Med 1993; 118: 255–267.
Rifai N, Sakamoto M, Lafi M, Guinan E . Measurement of plasma busulfan concentration by high-performance liquid chromatography with ultraviolet detection. Ther Drug Monit 1997; 19: 169–174.
Zhong S, Wyllie AH, Barnes D, Wolf CR, Spurr NK . Relationship between the GSTM1 genetic polymorphism and susceptibility to bladder, breast and colon cancer. Carcinogenesis 1993; 14: 1821–1824.
Stephens M, Smith NJ, Donnelly P . A new statistical method for haplotype reconstruction from population data. Am J Hum Genet 2001; 68: 978–989.
Ansari YTM, Rezgui S, Mezziani C, Desjean M, Vachon M et alBittencourt on behalf of the Pediatric Disease Working Parties of the European Blood and Marrow Transplant group. Association between busulfan exposure and outcome in children receiving intravenous busulfan before haematopoietic stem cell transplantation. Bone Marrow Transplant 2012; 47 Suppl: S40 (abstract 245).
Kim SD, Lee JH, Hur EH, Kim DY, Lim SN, Choi Y et al. Influence of GST gene polymorphisms on the clearance of intravenous busulfan in adult patients undergoing hematopoietic cell transplantation. Biol Blood Marrow Transplant 2011; 17: 1222–1230.
Miyagi SJ, Brown IW, Chock JM, Collier AC . Developmental changes in hepatic antioxidant capacity are age-and sex-dependent. J Pharmacol Sci 2009; 111: 440–445.
Srivastava A, Poonkuzhali B, Shaji RV, George B, Mathews V, Chandy M et al. Glutathione S-transferase M1 polymorphism: a risk factor for hepatic venoocclusive disease in bone marrow transplantation. Blood 2004; 104: 1574–1577.
Dix SP, Wingard JR, Mullins RE, Jerkunica I, Davidson TG, Gilmore CE et al. Association of busulfan area under the curve with veno-occlusive disease following BMT. Bone Marrow Transplant 1996; 17: 225–230.
Cantoni N, Gerull S, Heim D, Halter J, Bucher C, Buser A et al. Order of application and liver toxicity in patients given BU and CY containing conditioning regimens for allogeneic hematopoietic SCT. Bone Marrow Transplant 2011; 46: 344–349.
Kerbauy FR, Tirapelli B, Akabane H, Oliveira JS . The effect of administration order of BU and CY on toxicity in hematopoietic SCT in humans. Bone Marrow Transplant 2009; 43: 883–885.
We are thankful to all patients and their parents for consenting to participate in this study. This investigation was supported by grants provided by the Geneva Cancer League, CANSEARCH, Hans Wilsdorf, Telemaque and Charles Bruneau foundations. We thank the Swiss Oncology Group as our sponsor and the European Blood and Marrow Transplantation Pediatric (EBMT) working disease group for their support and for labeling this study as an EBMT trial. This study has been fully registered in a public trials registry as part of an ongoing prospective EBMT multicentric study (register at Clinical Trials.gov, NCT01257854). It is submitted on behalf of the Pediatric Disease Working Parties of the European Blood and Marrow Transplant group and is an EBMT label study (EudraCT number: 2009-018105-41).
The authors declare no conflict of interest.
Supplementary Information accompanies the paper on Bone Marrow Transplantation website
About this article
Cite this article
Ansari, M., Rezgui, M., Théoret, Y. et al. Glutathione S-transferase gene variations influence BU pharmacokinetics and outcome of hematopoietic SCT in pediatric patients. Bone Marrow Transplant 48, 939–946 (2013) doi:10.1038/bmt.2012.265
- hematopoietic SCT
Comparison of Different Conditioning Regimens in Allogeneic Hematopoietic Stem-Cell Transplantation Shows Superiority of Total Body Irradiation–Based Regimen for Younger Patients With Acute Leukemia: A Nationwide Study
Clinical Lymphoma Myeloma and Leukemia (2019)
Impact of GSTA1 Polymorphisms on Busulfan Oral Clearance in Adult Patients Undergoing Hematopoietic Stem Cell Transplantation
Genetic susceptibility to hepatic sinusoidal obstruction syndrome in pediatric patients undergoing HSCT
Biology of Blood and Marrow Transplantation (2019)
Personalized pharmacokinetic targeting with busulfan in allogeneic hematopoietic stem cell transplantation in infants with acute lymphoblastic leukemia
International Journal of Hematology (2019)
The pharmacokinetics and pharmacodynamics of busulfan when combined with melphalan as conditioning in adult autologous stem cell transplant recipients
Annals of Hematology (2018)