Katalin Csordás

Candidate gene association study in pediatric acute lymphoblastic leukemia evaluated by Bayesian network based Bayesian multilevel analysis of relevance

BackgroundWe carried out a candidate gene association study in pediatric acute lymphoblastic leukemia (ALL) to identify possible genetic risk factors in a Hungarian population.MethodsThe results were evaluated with traditional statistical methods and with our newly developed Bayesian network based Bayesian multilevel analysis of relevance (BN-BMLA) method. We collected genomic DNA and clinical data from 543 children, who underwent chemotherapy due to ALL, and 529 healthy controls. Altogether 66 single nucleotide polymorphisms (SNPs) in 19 candidate genes were genotyped.ResultsWith logistic regression, we identified 6 SNPs in the ARID5B and IKZF1 genes associated with increased risk to B-cell ALL, and two SNPs in the STAT3 gene, which decreased the risk to hyperdiploid ALL. Because the associated SNPs were in linkage in each gene, these associations corresponded to one signal per gene. The odds ratio (OR) associated with the tag SNPs were: OR = 1.69, P = 2.22x10-7 for rs4132601 (IKZF1), OR = 1.53, P = 1.95x10-5 for rs10821936 (ARID5B) and OR = 0.64, P = 2.32x10-4 for rs12949918 (STAT3). With the BN-BMLA we confirmed the findings of the frequentist-based method and received additional information about the nature of the relations between the SNPs and the disease. E.g. the rs10821936 in ARID5B and rs17405722 in STAT3 showed a weak interaction, and in case of T-cell lineage sample group, the gender showed a weak interaction with three SNPs in three genes. In the hyperdiploid patient group the BN-BMLA detected a strong interaction among SNPs in the NOTCH1, STAT1, STAT3 and BCL2 genes. Evaluating the survival rate of the patients with ALL, the BN-BMLA showed that besides risk groups and subtypes, genetic variations in the BAX and CEBPA genes might also influence the probability of survival of the patients.ConclusionsIn the present study we confirmed the roles of genetic variations in ARID5B and IKZF1 in the susceptibility to B-cell ALL. With the newly developed BN-BMLA method several gene-gene, gene-phenotype and phenotype-phenotype connections were revealed. We showed several advantageous features of the new method, and suggested that in gene association studies the BN-BMLA might be a useful supplementary to the traditional frequentist-based statistical method.

Comparison of pharmacokinetics and toxicity after high-dose methotrexate treatments in children with acute lymphoblastic leukemia

We carried out a detailed comparative study of the pharmacokinetics and toxicity of methotrexate (MTX) and 7-hydroxy-methotrexate (7-OH-MTX) after high-dose intravenous methotrexate (HD-MTX) in children with acute lymphoblastic leukemia (ALL). Overall, 65 children were treated with 5 g/m2/24 h MTX and 88 children were treated with 2 g/m2/24 h MTX according to ALL-BFM 95 and ALL IC-BFM 2002 protocols (mean age: 6.4 years, range 1.0–17.9 years). A total of 583 HD-MTX courses were analyzed. Serum MTX and 7-OH-MTX levels were measured at 24, 36, and 48 h, and cerebrospinal fluid (CSF) MTX levels were determined 24 h after the initiation of the infusion. The area under the concentration–time curve was calculated. Hepatotoxicity, nephrotoxicity, and bone marrow toxicity were estimated by routine laboratory tests. We investigated pharmacokinetics and toxicity in distinct age groups (<6 and >14 years). 5 g/m2/24 h treatments resulted in higher serum and CSF MTX and 7-OH-MTX levels (P<0.05). The CSF penetration rate of MTX was independent of the MTX dose [2.3% (95% confidence interval: 1.7–2.5%) vs. 2.8% (95% confidence interval: 2.4–3%)]. The CSF MTX concentration was correlated with the 24 h MTX serum level (r=0.38, P<0.0001). Repeated treatments did not alter MTX or 7-OH-MTX levels. 7-OH-MTX levels were correlated with nephrotoxicity (r=0.36, P<0.0001). Higher MTX levels and toxicity occurred more frequently in children aged older than 14 years (P<0.05). Therapeutic serum and CSF MTX concentrations can be achieved more reliably with 5 g/m2/24 h treatments. To predict the development of toxicity, monitoring of the level of the 7-OH-MTX is useful. Monitoring of pharmacokinetics is essential to prevent the development of severe adverse events in adolescents.

Associations of novel genetic variations in the folate-related and ARID5B genes with the pharmacokinetics and toxicity of high-dose methotrexate in paediatric acute lymphoblastic leukaemia.

High‐dose methotrexate (HD‐MTX) plays an important role in the consolidation therapy of acute lymphoblastic leukaemia (ALL) in many treatment regimens worldwide. However, there is a large interpatient variability in the pharmacokinetics and toxicity of the drug. We investigated the influence of single nucleotide polymorphisms (SNPs) in genes of the folate metabolic pathway, transporter molecules and transcription proteins on the pharmacokinetics and toxicity of MTX and 7‐hydroxy‐methotrexate (7‐OH‐MTX). 63 SNPs of 14 genes were genotyped and a total of 463 HD‐MTX courses (administered according to the ALL‐BFM 95 and ALL IC‐BFM 2002 protocols) were analysed. Haematological, hepatic and renal toxicities, estimated by routine laboratory parameters were evaluated. Random forest and regression trees were used for variable selection and model building. Linear mixed models were established to prove the significance of the selected variables. SNPs (rs4948502, rs4948496, rs4948487) of the ARID5B gene were associated with the serum levels of MTX (P < 0·02), serum levels and area under the curve of 7‐OH‐MTX (P < 0·02) and with hypoproteinaemia (P = 0·004). SLCO1B1 rs4149056 also showed a significant association with serum MTX levels (P < 0·001). Our findings confirm the association of novel genetic variations in folate‐related and ARID5B genes with the serum MTX levels and acute toxicity.

In interaction with gender a common CYP3A4 polymorphism may influence the survival rate of chemotherapy for childhood acute lymphoblastic leukemia

CYP3A4 has an important role in the metabolisms of many drugs used in acute lymphoblastic leukemia (ALL) therapy; still, there are practically no publications about the role of CYP3A4 polymorphisms in ALL pharmacogenomics. We genotyped eight common single-nucleotide polymorphisms (SNPs) in the CYP3A4 and CYP3A5 genes in 511 children with ALL and investigated whether they influenced the survival of the patients. We involved additional 127 SNPs in 34 candidate genes and searched for interactions with respect to the survival rates. Significant association between the survival rates and the common rs2246709 SNP in the CYP3A4 gene was observed. The gender of the patients and the rs1076991 in the MTHFD1 gene strongly influenced this effect. We calculated new risk assessments involving the gender-rs2246709 interaction and showed that they significantly outperformed the earlier risk-group assessments at every time point. If this finding is confirmed in other populations, it can have a considerable prognostic significance.

Pharmacogenetic analysis of high-dose methotrexate treatment in children with osteosarcoma

Inter-individual differences in toxic symptoms and pharmacokinetics of high-dose methotrexate (MTX) treatment may be caused by genetic variants in the MTX pathway. Correlations between polymorphisms and pharmacokinetic parameters and the occurrence of hepato- and myelotoxicity were studied. Single nucleotide polymorphisms (SNPs) of the ABCB1, ABCC1, ABCC2, ABCC3, ABCC10, ABCG2, GGH, SLC19A1 and NR1I2 genes were analyzed in 59 patients with osteosarcoma. Univariate association analysis and Bayesian network-based Bayesian univariate and multilevel analysis of relevance (BN-BMLA) were applied. Rare alleles of 10 SNPs of ABCB1, ABCC2, ABCC3, ABCG2 and NR1I2 genes showed a correlation with the pharmacokinetic values and univariate association analysis. The risk of toxicity was associated with five SNPs in the ABCC2 and NR1I2 genes. Pharmacokinetic parameters were associated with four SNPs of the ABCB1, ABCC3, NR1I2, and GGH genes, and toxicity was shown to be associated with ABCC1 rs246219 and ABCC2 rs717620 using the univariate and BN-BMLA method. BN-BMLA analysis detected relevant effects on the AUC0-48 in the following SNPs: ABCB1 rs928256, ABCC3 rs4793665, and GGH rs3758149. In both univariate and multivariate analyses the SNPs ABCB1 rs928256, ABCC3 rs4793665, GGH rs3758149, and NR1I2 rs3814058 SNPs were relevant. These SNPs should be considered in future dose individualization during treatment.

Subgroups of paediatric acute lymphoblastic leukaemia might differ significantly in genetic predisposition to asparaginase hypersensitivity

L-asparaginase (ASP) is a key element in the treatment of paediatric acute lymphoblastic leukaemia (ALL). However, hypersensitivity reactions (HSRs) to ASP are major challenges in paediatric patients. Our aim was to investigate genetic variants that may influence the risk to Escherichia coli-derived ASP hypersensitivity. Sample and clinical data collection was carried out from 576 paediatric ALL patients who were treated according to protocols from the Berlin—Frankfurt—Münster Study Group. A total of 20 single nucleotide polymorphisms (SNPs) in GRIA1 and GALNT10 genes were genotyped. Patients with GRIA1 rs4958351 AA/AG genotype showed significantly reduced risk to ASP hypersensitivity compared to patients with GG genotype in the T-cell ALL subgroup (OR = 0.05 (0.01–0.26); p = 4.70E-04), while no such association was found in pre-B-cell ALL. In the medium risk group two SNPs of GRIA1 (rs2055083 and rs707176) were associated significantly with the occurrence of ASP hypersensitivity (OR = 0.21 (0.09–0.53); p = 8.48E-04 and OR = 3.02 (1.36–6.73); p = 6.76E-03, respectively). Evaluating the genders separately, however, the association of rs707176 with ASP HSRs was confined only to females. Our results suggest that genetic variants of GRIA1 might influence the risk to ASP hypersensitivity, but subgroups of patients can differ significantly in this respect.

Early Increase in Complement Terminal Pathway Activation Marker sC5b-9 is Predictive for the Development of Thrombotic Microangiopathy after Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT)-associated thrombotic microangiopathy (TA-TMA) is a multifactorial complication, and its prediction is largely unresolved. Our aim was to analyze changes of complement profile after HSCT to identify potential markers of TA-TMA development. Thirty-three consecutive pediatric patients (9.6 ± 4.4 years old) who underwent allogeneic HSCT due to malignant (n = 17) or nonmalignant (n = 16) indications were included in this study. Graft-versus-host disease (GVHD) was diagnosed using Glucksberg criteria, viral reactivation was monitored, 5 different TA-TMA diagnostic criteria were applied, and all important clinical and laboratory parameters of TA-TMA activity were registered. Complement pathway activities, components and terminal pathway activation marker (sC5b-9) levels were systematically measured before transplantation and on days 28, 56, and 100 after HSCT. During the first 100 days after HSCT, 1 of 33 patients died (day 50, multiple organ failure), whereas 10 subjects met the criteria for TA-TMA, typically on day 61 (range, 16 to 98 days). TA-TMA was preceded by acute GVHD in 3 of 10 patients, by viral reactivation in 2 of 10, or by both in 4 of 10 cases. Baseline sC5b-9 levels did not differ in patients without (200 [interquartile range, 144 to 266] ng/mL), or with (208 [interquartile range, 166 to 271] ng/mL) subsequent TA-TMA; however, on day 28 significant differences were observed (201 [interquartile range, 185 to 290] ng/mL versus 411 [interquartile range, 337 to 471] ng/mL; P = .004). Importantly, all 10 patients with TMA showed increase in sC5b-9 level from baseline level to day 28, whereas in patients without TMA the same tendency was observed for only 9 of 23 patients (P = .031). No additional complement parameters were closely associated with the development of TA-TMA. Development of TA-TMA occurred in 30% of our patients, typically after GVHD and/or viral reactivation. However, early raise of sC5b-9 activation marker was predictive for later development of TA-TMA, and should therefore be considered as an alarming sign necessitating a careful monitoring of all TA-TMA activity markers. Further studies enrolling a higher number of patients are necessary to determine if terminal pathway activation is an independent predictor of TA-TMA.

Some GCR Polymorphisms (N363S, ER22/23EK, and Bcl-1) May Influence Steroid-induced Toxicities and Survival Rates in Children With ALL.

We investigated whether an altered individual glucocorticoid sensitivity due to particular glucocorticoid receptor single-nucleotide polymorphisms (SNPs) (N363S, ER22/23EK, and Bcl-1) influences the susceptibility to steroid-related toxicities, prognostic factors, and survival rates in children with acute lymphoblastic leukemia. In total, 346 pediatric patients with acute lymphoblastic leukemia were enrolled in our study. Their carrier status was investigated by allele-specific polymerase chain reaction analysis. Clinical and laboratory signs of glucocorticoid-related toxicities, day-8 prednisone response, 5-year event-free survival, and 5-year overall survival rates were analyzed and compared retrospectively. Hepatotoxicity occurred significantly more often in 363S carriers (P=0.004), and glucose metabolism abnormalities were more common in 363S carriers (P=0.001), but did not occur in patients with the ER22/23EK SNP. Hypertension and central nervous system/behavioral changes did not occur in patients with the ER22/23EK SNP. None of the patients with the N363S SNP, the ER22/23EK polymorphism, or the GG genotype for the Bcl-1 polymorphism had a poor prednisone response. The 363S carriers had significantly better 5-year event-free survival (P=0.012) and 5-year overall survival (P=0.013) rates compared with noncarriers. The Bcl-1 SNP was not associated with any of the toxicities investigated or survival. Children with the N363S polymorphism in the glucocorticoid receptor gene were more prone to steroid-related toxicities, whereas those with the ER22/23EK polymorphism were less susceptible. Children with the N363S polymorphism may have more favorable survival rates.

Antithymocyte Globuline Therapy and Bradycardia in Children

In antithymocyte globulin (ATG) treated patients occasionally bradycardia has been noticed. Therefore, we retrospectively analyzed the occurrence of bradycardia in ATG-treated children. Using medical records between 2007 and 2012 we identified children undergoing a combined therapy with ATG and glucocorticoids (ATG group, n = 22). The incidence of bradycardia was compared to that registered in children treated with glucocorticoids alone (glucocorticoid alone group, n = 21). Heart rates (HR) were registered before and on days 0–3, 4–7 and 8–14 after the ATG or steroid administration. The rate of bradycardic episodes was higher during ATG therapy than in the steroid alone group, while severe bradycardia occurred only in the ATG group (97 versus 32, p = 0.0037, and 13 versus 0, p = 0.0029, respectively). There was an interaction between the time and treatment group on HR (p = 0.046). Heart rates in ATG and steroid alone groups differed significantly on day 0–3 and day 4–7 (p = 0.046, p = 0.006, respectively). Within the ATG group HR was lower on days 4–7 compared to the days before and the days 8–14 values (p < 0.001, 95%CI: 0.020–0.074). These findings indicate that transient asymptomatic bradycardia is probably more common with ATG therapy than previously reported. HR should be closely monitored during and after ATG therapy.

Változások az őssejt-transzplantációhoz társult thromboticus microangiopathia diagnosztikus kritériumrendszerében

Hematopoietic stem cell transplantation associated thrombotic microangiopathy is a multifactorial complication, and has variable incidence in study populations due to different diagnostic criteria. The diversity of activity parameters, like elevated laktat-dehidrogenaz, hematological parameters and kidney function are not specific variables after stem cell transplantation. Dysregulation of the classical and alternative pathway can play an important role in the pathomechanism of thrombotic microangiopathy, but the understanding of the role of complement activation under transplantation conditions requires further investigation. Monitoring of complement parameters, including terminal complement pathway activation complex during transplantation may help physicians to improve diagnostic strategy, to evaluate therapeutical options and to predict and follow up efficacy of complement blockade methods and supportive therapy. This review focuses on the development of diagnostic criteria and therapeutical options in thrombotic microangiopathy, and presents some preliminary findings while using different diagnostic criteria in pediatric patients. Orv Hetil. 2017; 158(27): 1043-1050.