Glutathione S-transferase P1 genetic polymorphisms and susceptibility to childhood acute lymphoblastic leukaemia

Glutathione S-transferase pi (GSTP1) is involved in the metabolism of carcinogens. We assessed the association of GSTP1 genetic polymorphisms and the susceptibility to childhood acute lymphoblastic leukaemia (ALL) by conducting a case-control study on 278 ALL patients and 303 healthy controls, both of French-Canadian origin. The carriers of the GSTP1*B variant (only the Val105 substitution) were found to be associated with an increased risk of ALL [odds ratio (OR) = 1.5, 95% confidence interval (CI) 1.1-2.0], whereas the GSTP1*C variant (both Val105 and Val114) was underrepresented in cases. Thus, genetic variants of GSTP1 that are expressed at the protein level appear to contribute differently to the risk of ALL, probably because of distinct substrate specificities. When combined with other GST genotypes, we found that the combination of GSTP1*B and GSTM1 null genotypes further increased the risk of ALL (OR = 2.1; 95% CI-1.3-3.4). These findings suggest that GSTP1 variants (alone or combined with other GSTs) represent significant genetic determinants of childhood ALL.     

Bone-marrow relapse in acute lymphoblastic leukaemia in childhood.

The outcome after bone-marrow relapse was assessed in 53 children with acute lymphoblastic leukaemia (ALL). Twenty-five out of 37 children (67%) whose first remission ended in relapse during treatment (group A) achieved a second remission, as did 15 out of 16 (94%) who relapsed after treatment had been stopped (group B). Nevertheless, the median duration of second remission was only 12 weeks in group A and 35 weeks in group B. The median survival from time of relapse was 32 weeks in group A and 75 weeks in group B. It is concluded that marrow relapse is equally serious whether it occurs during treatment or after treatment has been stopped, and that most children with ALL have a single chance of cure at the time of diagnosis.     

Clofarabine in the treatment of acute myeloid leukaemia and acute lymphoblastic leukaemia: a review

Clofarabine, a synthesised adenosine nucleoside, has recently demonstrated single-agent activity in the acute leukaemias. Originally developed to capture the best qualities of cladribine and fludarabine, clofarabine contains halogenated carbons, rendering it resistant to inactivating enzymes and maintaining its stability in acidic environments. Like other adenosine nucleosides, clofarabine acts by inhibiting ribonucleotide reductase and DNA polymerase, thereby depleting the amount of intracellular deoxynucleoside triphosphates available for DNA replication and also resulting in premature DNA chain termination. Clofarabine has also been shown to induce apoptosis in transformed cell lines, indicating that clofarabine results in cell death in both cycling and non-cycling cells. Interest in the development of clofarabine was initially hampered by the availability of other active nucleoside analogues for the treatment of haematological malignancies. However, the results of several early-phase trials evaluating the use of clofarabine in acute leukaemias in adults and children have rekindled enthusiasm for further investigation into its use. This article describes the development, pharmacology, toxicity and clinical activity of clofarabine, as well as discuss its potential role in the treatment of acute leukaemia.     

Clofarabine in the treatment of acute myeloid leukaemia and acute lymphoblastic leukaemia: a review

Clofarabine, a synthesised adenosine nucleoside, has recently demonstrated single-agent activity in the acute leukaemias. Originally developed to capture the best qualities of cladribine and fludarabine, clofarabine contains halogenated carbons, rendering it resistant to inactivating enzymes and maintaining its stability in acidic environments. Like other adenosine nucleosides, clofarabine acts by inhibiting ribonucleotide reductase and DNA polymerase, thereby depleting the amount of intracellular deoxynucleoside triphosphates available for DNA replication and also resulting in premature DNA chain termination. Clofarabine has also been shown to induce apoptosis in transformed cell lines, indicating that clofarabine results in cell death in both cycling and non-cycling cells. Interest in the development of clofarabine was initially hampered by the availability of other active nucleoside analogues for the treatment of haematological malignancies. However, the results of several early-phase trials evaluating the use of clofarabine in acute leukaemias in adults and children have rekindled enthusiasm for further investigation into its use. This article describes the development, pharmacology, toxicity and clinical activity of clofarabine, as well as discuss its potential role in the treatment of acute leukaemia.     

Changing patterns of acute lymphoblastic leukaemia in Nigeria

An increase in the number of Nigerian patients with acute lymphoblastic leukaemia (ALL), relative to those having acute myelogenous leukaemia, was predicted some years ago. This was expected to result from an enhanced socio-economic status of most members of the general population and improved nutrition. A review of the features of ALL patients seen in University College Hospital, Ibadan, during different periods over the past three decades revealed not only the predicted changes but also an increasing proportion of pediatric and female patients. Except for an unusual number of patients with the rare L3 morphological variant seen within the last 2 years, little else changed in the clinical and laboratory features of the disease. Atrophy of the thymus resulting from malnutrition is thought to inhibit the occurrence of common-ALL in the first decade of life. This inhibition is removed by improved nutrition, thus allowing more cases of common-ALL to develop in children. The trend in Nigeria has been observed earlier among Arabs in the Gaza Strip in the Sinai Peninsula. If the hypothesis is correct, undernutrition occurring for a long enough time in a previously well-nourished population should lead to changes opposite to those observed. The increasing percentage of patients who are either young, female or of high socio-economic class imply better prognosis for more Nigerian ALL patients.     

L-asparaginase-induced coagulopathy in children with acute lymphoblastic leukaemia

Haemostatic changes induced with vincristine (VCR), prednisone (PDN) and L-asparaginase (L-ase) in 53 children with ALL were prospectively evaluated. Relative to pretreatment values, mean FG concentration diminished significantly in the first week with a minimal level in the third week and PT was prolonged during the first weeks of induction. APTT decreased significantly in the last week and after cessation of L-ase therapy. Mean concentration of factor VIII remained elevated during the entire period of L-ase therapy. Three children (5.6%) developed a cerebral thrombo/haemorrhagic complication. These data demonstrate that the tendency for thrombosis is the predominant clinical manifestation of L-ase-induced coagulopathy, when the drug is associated with VCR and PDN.     

在儿童急性淋巴细胞白血病中大剂量甲氨蝶呤药物毒性与基因多态性的相关性研究进展

急性淋巴细胞白血病(ALL)是儿童最常见的恶性肿瘤。大剂量MTX是ALL治疗中最常用的药物之一,但治疗过程中常常产生如溃疡性口炎、恶心、发热和白细胞减少等不良反应。现有研究指出,相关基因通过影响药物代谢酶、靶点、转运体的表达,进而影响MTX的代谢。本文对可能影响MTX代谢的多种基因是否可以准确预测出MTX治疗的不良反应进行综述。     

Polymorphisms of microsomal epoxide hydrolase and glutathione S-transferase P1 in a male Turkish population

Polymorphic genes encoding drug-metabolizing enzymes may account for interindividual differences in certain types of diseases especially cancer. In this study, microsomal epoxide hydrolase (EPHX1) and glutathione S-transferase P1 (GSTP1) gene polymorphisms were determined among 133 healthy males of a Turkish population. Frequencies of EPHX1 and GSTP1 gene polymorphisms were determined by using the polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) method. The observed genotype frequencies of EPHX1 exon 3 were Tyr113Tyr:50.4%, Tyr113His: 42.1%, His113His: 7.5% and EPHX1 exon 4 were His139His: 69.2%, His139Arg: 28.6%, Arg133Arg: 2.2%. GSTP1 exon 5 genotype frequencies were Ile105Ile: 58.7%, Ile105Val: 35.3%, Val105Val: 6.0% and GSTP1 exon 6 genotype frequencies were Ala114Ala: 85.0%, Ala114Val: 14.3%, Val114Val: 0.7%. These results reveal that the frequencies of EPHX1 and GSTP1gene polymorphisms in a small sampling of males within a Turkish population are similar to European Caucasian populations.     

Polymorphisms of glutathione S-transferase genes (GSTM1, GSTP1 and GSTT1) and bladder cancer susceptibility in the Turkish population

We investigated the effect of the GSTM1 and GSTT1 null genotypes, and GSTP1 313 A/G polymorphism on bladder cancer susceptibility in a case control study of 121 bladder cancer patients, and 121 age- and sex-matched controls of the Turkish population. The adjusted odds ratio for age, sex, and smoking status is 1.94 [95% confidence intervals (CI) 1.15-3.26] for the GSTM1 null genotype, and 1.75 (95% CT 1.03-2.99) for the GSTP1 313 A/G or G/G genotypes. GSTT1 was shown not to be associated with bladder cancer. Combination of the two high-risk genotypes. GSTM1 null and GSTP1 313 A/G or G/G, revealed that the risk increases to 3.91-fold (95% CI 1.88-8.13) compared with the combination of the low-risk genotypes of these loci. In individuals with the combined risk factors of cigarette smoking and the GSTM1 null genotype, the risk of bladder cancer is 2.81 times (95% CI 1.23-6.35) that of persons who both carry the GSTM1-present genotype and do not smoke. Similarly, the risk is 2.38-fold (95% CI 1.12-4.95) for the combined GSTP1 313 A/G and G/ G genotypes and smoking. These findings support the role for the GSTM1 null and the GSTP1 313 AG or GG genotypes in the development of bladder cancer. Furthermore, gene-gene (GSTM1-GSTP1) and gene-environment (GSTM1-smoking, GSTP1-smoking) interactions increase this risk substantially.     

Methotrexate-induced malabsorption in children with acute lymphoblastic leukaemia.

A one-hour D-xylose absorption test was performed on 18 children with acute lymphoblastic leukaemia. Xylose absorption was normal in children who had not received methotrexate, but there was a significant degree of malabsorption in those who had taken methotrexate within the previous seven days. There was a progressive and significant increase in malabsorption related to the cumulative dose of methotrexate. These findings provide further evidence that regular methotrexate treatment every seven days is more toxic than if it is more widely spaced. The spacing of treatment is currently under investigation.     

Combination chemotherapy for acute lymphoblastic leukaemia in adults.

Fifty-one adults with acute lymphoblastic leukaemia were entered into a trial of intense initial chemotherapy and early "prophylaxis" of the central nervous system (CNS). Initial treatment with OPAL (Oncovin (vincristine), prednisolone, adriamycin (doxorubicin), and L-asparaginase (colaspase)) followed by craniospinal or cranial irradiation and intrathecal methotrexate produced remission in 36 patients (71%). Seventeen of these patients relapsed three to 18 months after the start of remission; the remainder had been in remission for 12 to 52 months by the end of the study. The predicted median duration of complete remission was 18.5 months. None of the four patients who initially had clinical evidence of CNS disease, three of whom also had leukaemic cells identical to those found in Burkitt's lymphoma, achieved remission. Those patients who initially had hepatomegaly or splenomegaly had a shorter remission than those without. The predicted median survival was 27 months in those who achieved complete remission, one month in those who did not, and 21 months overall. The addition of colaspase and doxorubicin to vincristine and prednisolone and the use of early CNS treatment clearly improved the remission rate among adults with acute lymphoblastic leukaemia, though the presence and length of remission was affected by the extent of disease at presentation. Burkitt-like leukaemia, which had a poor prognosis, is probably a separate disease and may benefit from a different therapeutic approach.