Nina Erčulj

Influence of folate pathway polymorphisms on high-dose methotrexate-related toxicity and survival in childhood acute lymphoblastic leukemia

Abstract The prediction of high-dose methotrexate (HD-MTX) toxicity is a key issue in the individualization of treatment in childhood acute lymphoblastic leukemia (ALL). Our aim was to evaluate the influence of MTX pathway polymorphisms on HD-MTX treat- ment outcome in children with ALL. In total, 167 children with ALL were genotyped for methylenetetrahydrofolate dehydrogenase (MTHFD1) 1958G > A, methylenetetrahydrofolate reductase (MTHFR) 677C > T and 1298A > C and thymidylate synthase (TYMS) 2R > 3R polymorphisms. The MTHFD1 1958A allele significantly reduced the odds of hepatotoxicity (adjusted p = 0.009), while the TYMS 3R allele significantly reduced the odds of leukocytopenia and thrombocytopenia (adjusted p = 0.005 and adjusted p = 0.002, respectively). MTHFR polymorphisms did not influence HD-MTX-related toxicity, but a significant effect of MTHFR 677C > T–TYMS 2R > 3R and MTHFD1 1958G > A–MTHFR 677C > T interactions on HD-MTX-related toxicity was observed. None of the investigated polymorphisms influenced survival. Our study suggests an important role of polymorphisms and gene–gene interactions within the folate pathway in HD-MTX-related toxicity in childhood ALL.

The influence of gemcitabine pathway polymorphisms on treatment outcome in patients with malignant mesothelioma.

Objective Identification of biomarkers that could predict gemcitabine efficacy and toxicity is a key issue in the development of individualized therapy. The aim of our study was to evaluate the influence of gemcitabine pathway polymorphisms on treatment outcome in patients with malignant mesothelioma (MM). Methods In total, 107 patients with MM, treated with gemcitabine-platinum chemotherapy, were genotyped for 11 polymorphisms in deoxycytidine kinase, ribonucleotide reductase M1 (RRM1), and cytidine deaminase genes using KASPar assays. Binary logistic regression was used to evaluate the influence of selected polymorphisms on tumor response and occurrence of treatment-related toxicity, while their influence on survival was estimated by Cox proportional hazards model. A haplotype analysis was carried out to assess the combined effect of RRM1 polymorphisms. Results Deoxycytidine kinase and cytidine deaminase polymorphisms did not influence treatment outcome in patients with MM. In multivariable analysis, RRM1 2927A>C polymorphism significantly decreased overall survival probability [hazard ratio (HR)=2.02; 95% confidence interval (CI)=1.11–3.65; P=0.021]. Two promoter polymorphisms, RRM1 −524T>C and −37C>A, decreased the odds of nausea/vomiting grade≥2 occurrence [odds ratio (OR)=0.25; 95% CI=0.10–0.60; P=0.002 and OR=0.26; 95% CI=0.11–0.63; P=0.003, respectively]. RRM1 TTCCA haplotype was associated with worse tumor response (OR=16.67; 95% CI=2.38–100.00; P=0.004) and worse overall survival (HR=2.97; 95% CI=1.46–6.06; P=0.003) compared with the most frequent TTCAA haplotype, while TCACA haplotype influenced nausea/vomiting grade≥2 occurrence (OR=0.27; 95% CI=0.12–0.60; P=0.001). Conclusion RRM1 polymorphisms as well as haplotypes showed an association with gemcitabine treatment efficacy and toxicity; therefore, they should be validated as potential markers for the prediction of clinical outcome in patients with MM.

The influence of platinum pathway polymorphisms on the outcome in patients with malignant mesothelioma

BACKGROUND Platinum-based therapy is widely used in the treatment of malignant mesothelioma (MM); however, the efficacy and toxicity of platinum agents vary greatly between patients. The aim of our study was to evaluate the influence of platinum pathway polymorphisms on treatment outcome in patients with MM. PATIENTS AND METHODS In total, 133 patients with MM treated with (n = 97) or without (n = 36) platinum-based therapy were genotyped for common XPD, ERCC1, and GSTP1 polymorphisms, as well as for GSTM1 and GSTT1 gene deletion. Haplotype analysis was carried out to assess the combined effect of nucleotide excision repair (NER) polymorphisms. RESULTS GST polymorphisms were not associated with treatment outcome in patients with MM. In the group of platinum-treated patients with MM, ERCC1 8092C/C wild-type genotype significantly influenced progression-free survival (PFS) in multivariable analysis accounting for clinical variables (P = 0.034). XPD 312Asp/Asp and ERCC1 8092C/C wild-type genotypes also increased the odds of treatment-related toxic effects in univariable as well as multivariable analysis. The association of wild-type NER genotypes with better PFS and higher susceptibility to treatment-related toxic effects was confirmed in haplotype analysis. CONCLUSIONS Our results suggest that polymorphisms in NER pathway influence platinum-treatment efficacy and toxicity; therefore, these should be further evaluated as potential markers for the prediction of clinical outcome in patients with MM.

Genetic polymorphisms in homologous recombination repair genes in healthy Slovenian population and their influence on DNA damage.

Genetic polymorphisms in homologous recombination repair genes in healthy Slovenian population and their influence on DNA damage Background. Homologous recombination (HR) repair is an important mechanism involved in repairing double-strand breaks in DNA and for maintaining genomic stability. Polymorphisms in genes coding for enzymes involved in this pathway may influence the capacity for DNA repair. The aim of this study was to select tag single nucleotide polymorphisms (SNPs) in specific genes involved in HR repair, to determine their allele frequencies in a healthy Slovenian population and their influence on DNA damage detected with comet assay. Materials and methods. In total 373 individuals were genotyped for nine tag SNPs in three genes: XRCC3 722C>T, XRCC3 -316A>G, RAD51 -98G>C, RAD51 -61G>T, RAD51 1522T>G, NBS1 553G>C, NBS1 1197A>G, NBS1 37117C>T and NBS1 3474A>C using competitive allele-specific amplification (KASPar assay). Comet assay was performed in a subgroup of 26 individuals to determine the influence of selected SNPs on DNA damage. Results. We observed that age significantly affected genotype frequencies distribution of XRCC3 -316A>G (P = 0.039) in healthy male blood donors. XRCC3 722C>T (P = 0.005), RAD51 -61G>T (P = 0.023) and NBS1 553G>C (P = 0.008) had a statistically significant influence on DNA damage. Conclusions.XRCC3 722C>T, RAD51 -61G>T and NBS1 553G>C polymorphisms significantly affect the repair of damaged DNA and may be of clinical importance as they are common in Slovenian population.

DNA Repair Polymorphisms and Treatment Outcomes of Patients with Malignant Mesothelioma Treated with Gemcitabine-Platinum Combination Chemotherapy

Introduction: Genetic polymorphisms that affect DNA repair capacity can modulate the efficacy and toxicity of cytotoxic agents. Therefore, the aim of our study was to evaluate the influence of genetic variability in DNA repair genes on treatment outcome in patients with malignant mesothelioma (MM) treated with gemcitabine-platinum combination chemotherapy. Methods: In total, 109 patients with MM were genotyped for 10 polymorphisms in XRCC1, NBN, RAD51, and XRCC3 genes. The influence of selected polymorphisms on tumor response and occurrence of treatment-related toxicity was determined by logistic regression analysis, whereas their influence on survival was estimated by Cox proportional hazards model. Results: There were no associations between the investigated polymorphisms and tumor response, but we observed a significant association between XRCC1 399Gln allele and reduced overall survival (hazards ratio = 1.70; 95% confidence interval [CI] 1.06–2.73; p = 0.028). Interaction between XRCC1 399Gln allele and C-reactive protein levels revealed that carriers of at least one XRCC1 399Gln allele with C-reactive protein levels above median had significantly shorter overall survival time compared with other patients (12.9 months versus 25.3 months, log-rank p < 0.001). We also observed an association between XRCC1 399Gln and lower frequency of leukopenia (odds ratio [OR] = 0.25; 95% CI 0.09–0.67; p = 0.006), neutropenia (OR = 0.24; 95% CI 0.09–0.68; p = 0.007), and thrombocytopenia (OR = 0.27; 95% CI 0.09–0.84; p = 0.024). In addition, NBN 3474A>C, XRCC3 -316A>G, and Thr241Met polymorphisms showed significant associations with treatment-related toxicity. Conclusions: Our results support the hypothesis that DNA repair gene polymorphisms, particularly XRCC1 Arg399Gln, may modify the response to gemcitabine-platinum combination chemotherapy and, for the first time, show this effect in patients with MM.

The influence of folate pathway polymorphisms on high-dose methotrexate-related toxicity and survival in children with non-Hodgkin malignant lymphoma

Abstract Background. We evaluated the influence of folate pathway polymorphisms on high-dose methotrexate (HD-MTX) related toxicity in paediatric patients with T-cell non-Hodgkin lymphoma (NHL). Patients and methods. In total, 30 NHL patients were genotyped for selected folate pathway polymorphisms. Results. Carriers of at least one MTHFR 677T allele had significantly higher MTX area under the time-concentration curve levels at third MTX cycle (P = 0.003). These patients were also at higher odds of leucopoenia (P = 0.006) or thrombocytopenia (P = 0.041) and had higher number of different HD-MTX-related toxicity (P = 0.035) compared to patients with wild-type genotype. Conclusions. Our results suggest an important role of MTHFR 677C>T polymorphism in the development of HD-MTXrelated toxicity in children with NHL.

The association of folate pathway and DNA repair polymorphisms with susceptibility to childhood acute lymphoblastic leukemia.

Genetic factors may play an important role in susceptibility to childhood acute lymphoblastic leukemia (ALL). The aim of our study was to evaluate the associations of genetic polymorphisms in folate pathway and DNA repair genes with susceptibility to ALL. In total, 121 children with ALL and 184 unrelated healthy controls of Slovenian origin were genotyped for 14 polymorphisms in seven genes of folate pathway, base excision repair and homologous recombination repair (TYMS, MTHFR, OGG1, XRCC1, NBN, RAD51, and XRCC3). In addition, the exon 6 of NBN was screened for the presence of mutations using denaturing high performance liquid chromatography. Twelve polymorphisms were in Hardy-Weinberg equilibrium in controls and their genotype frequencies were in agreement with those reported in other Caucasian populations. Among the investigated polymorphisms and mutations, NBN Glu185Gln significantly decreased susceptibility to B-cell ALL (p=0.037), while TYMS 3R allele decreased susceptibility to T-cell ALL (p=0.011). Moreover, significantly decreased susceptibility to ALL was observed for MTHFR TA (p=0.030) and RAD51 GTT haplotypes (p=0.016). Susceptibility to ALL increased with the increasing number of risk alleles (ptrend=0.007). We also observed significant influence of hOGG-RAD51 and NBN-RAD51 interactions on susceptibility to ALL. Our results suggest that combination of several polymorphisms in DNA repair and folate pathways may significantly affect susceptibility to childhood ALL.

Is survivin expression prognostic or predictive in malignant pleural mesothelioma

Malignant pleural mesothelioma is an incurable cancer strongly associated with asbestos exposure and characterised by poor response to treatment. The inhibitor-of-apoptosis protein family member survivin is involved in apoptosis and proliferation and is expressed in cancer cells only. The aims of the present study were to elucidate whether survivin expression is associated with tumour cell apoptosis and proliferation and to assess the prognostic and predictive value of survivin expression in malignant pleural mesothelioma. Archival pleural mesothelioma tissue samples from 101 patients were immunohistochemically analysed for nuclear expression of survivin, for proliferation with the use of Ki-67 as marker and for apoptosis using active caspase-3 as a marker. Staining results and clinical data were included in a survival analysis. Survivin was highly expressed in tumour cell nuclei in all samples and this correlated positively with both apoptosis and proliferation, but did not have a significant prognostic value. We found significantly higher survivin expression in patients who responded to chemotherapy compared to patients with progressive disease. Survivin expression might contribute to treatment response prediction, but survivin expression in malignant pleural mesothelioma did not have prognostic significance.