mercaptopurine and Precursor-T-Cell-Lymphoblastic-Leukemia-Lymphoma

Sinusoidal obstruction syndrome (SOS) of the liver is a complication of chemotherapy most often encountered with hematopoietic stem cell transplant due to high-dose conditioning regimens, but it can also occur with regimens outside of the transplant setting. Mild-to-moderate SOS is a well-described 6-thioguanine toxicity; however, it has rarely been reported as secondary to 6-mercaptopurine, a related thiopurine. This report details a case of a 10-year-old male with T-cell acute lymphoblastic leukemia who developed severe SOS during maintenance therapy with 6-mercaptopurine, and a review of the related literature.

Topics: Child; Hepatic Veno-Occlusive Disease; Humans; Male; Mercaptopurine; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; T-Lymphocytes; Thioguanine

Flow cytometry immunophenotyping (FCM) is an undispensable tool for the diagnosis and for the treatment stratification of childhood acute lymphoblastic leukemia. The correlation of the EGIL-classification with prognostically relevant parameters like age, prednisone response and risk group is analyzed.. Between March 2000 and June 2009 12 patients less than 1 year of age, 1 836 patients with 1 to less than 6 years, 620 patients with 6 to less than 10 years, 615 patients with 10 to less than 15 years and 275 patients with 15 to less than 19 years were analyzed with a comprehensive 4-color antibody panel and classified according to the EGIL recommendations.. Bone marrow or peripheral blood mononuclear cells were isolated by ficoll gradient centrifugation, washed and stained with fluorochrome-conjugated antigen-specific monoclonal antibodies. Cell preparations were acquired and analyzed on a flow cytometer.. Centralized FCM was performed for 2 775 patients (82.6%) with B-cell precursor acute lymphoblastic leukemia, 493 patients (14.7%) with T-cell acute lymphoblastic leukemia and 90 patients (2,7%) with biphenotypic acute leukemia. There was a slight overall predominance of male (56.1%) over female (43.9%) patients. Patients with B-cell precursor ALL had a slightly more favourable outcome with a 10 y pEFS of 78 ± 1.0%, compared to patients with a T-ALL or BAL (biphenotypic acute leukemia) phenotype with a 10 y pEFS of 74 ± 1.8% (n.s.) or 69 ± 9.0% (p<0.009), respectively.. FCM according to the EGIL recommendations not only provides diagnostic lineage determination and subclassification but also enables an initial prognostic orientation before MRD (minimal residual disease)-based risk stratification becomes available.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Cell Lineage; Child; Child, Preschool; Cyclophosphamide; Cytarabine; Daunorubicin; Female; Flow Cytometry; Humans; Immunophenotyping; Infant; Leukemia, Biphenotypic, Acute; Male; Mercaptopurine; Methotrexate; Neoplasm, Residual; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Prognosis; Survival Analysis; Vincristine

In the ALL-BFM 95 trial for treatment of acute lymphoblastic leukemia, response to a prednisone pre-phase (prednisone response) was used for risk stratification in combination with age and white blood cell count at diagnosis, response to induction therapy and specific genetic high-risk features.. Cytomorphological marrow response was prospectively assessed on Day 15 during induction, and its prognostic value was analyzed in 1,431 patients treated on ALL-BFM 95.. The 8-year probabilities of event-free survival were 86.1%, 74.5%, and 46.4% for patients with M1, M2, and M3 Day 15 marrows, respectively. Compared to prednisone response, Day 15 marrow response was superior in outcome prediction in precursor B-cell and T-cell leukemia with, however, a differential effect depending on blast lineage. Outcome was poor in T-cell leukemia patients with prednisone poor-response independent of Day 15 marrow response, whereas among patients with prednisone good-response different risk groups could be identified by Day 15 marrow response. In contrast, prednisone response lost prognostic significance in precursor B-cell leukemia when stratified by Day 15 marrow response. Age and white blood cell count retained their independent prognostic effect.. Selective addition of Day 15 marrow response to conventional stratification criteria applied on ALL-BFM 95 (currently in use in several countries as regular chemotherapy protocol for childhood acute lymphoblastic leukemia) may significantly improve risk-adapted treatment delivery. Even though cutting-edge trial risk stratification is meanwhile dominated by minimal residual disease evaluation, an improved conventional risk assessment, as presented here, could be of great importance to countries that lack the technical and/or financial resources associated with the application of minimal residual disease analysis.

Topics: Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Biomarkers; Bone Marrow; Child; Child, Preschool; Cyclophosphamide; Cytarabine; Daunorubicin; Disease-Free Survival; Female; Humans; Infant; Lymphocyte Count; Male; Mercaptopurine; Neoplasm, Residual; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisolone; Prednisone; Prognosis; Prospective Studies; Remission Induction; Risk Assessment; Treatment Outcome; Vincristine

Myelotoxicity during thiopurine therapy is enhanced in patients, who because of single nucleotide polymorphisms have decreased activity of the enzyme thiopurine methyltransferase (TPMT) and thus more thiopurine converted into 6-thioguanine nucleotides. Of 601 children with acute lymphoblastic leukemia (ALL) who were treated by the NOPHO ALL-92 protocol, 117 had TPMT genotype determined, whereas for 484 patients only erythrocyte TPMT activity was available. The latter were classified as heterozygous, if TPMT activity was <14 IU/ml, or deficient (<1.0 IU/ml). 526 patients had TPMT wild type, 73 were presumed heterozygous, and two were TPMT deficient. Risk of relapse was higher for the 526 TPMT wild type patients than for the remaining 75 patients (18 vs 7%, P=0.03). In Cox multivariate regression analysis, sex (male worse; P=0.06), age (higher age worse, P=0.02), and TPMT activity (wild type worse; P=0.02) were related to risk of relapse. Despite a lower probability of relapse, patients in the low TPMT activity group did not have superior survival (P=0.82), possibly because of an excess of secondary cancers among these 75 patients (P=0.07). These data suggest that children with ALL and TPMT wild type might have their cure rate improved, if the pharmacokinetics/-dynamics of TPMT low-activity patients could be mimicked without a concurrent excessive risk of second cancers.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Biotransformation; Child; Child, Preschool; DNA Damage; Female; Genotype; Humans; Inactivation, Metabolic; Infant; Male; Mercaptopurine; Methylation; Methyltransferases; Neoplasm Proteins; Neoplasms, Second Primary; Polymorphism, Genetic; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Recurrence; Risk; Scandinavian and Nordic Countries; Thioguanine

6-mercaptopurine (6-MP) is widely used in the treatment of acute lymphoblastic leukemia (ALL), and its cytotoxicity is primarily mediated by thioguanine nucleotide (TGN) metabolites. A recent genomewide association study has identified germline polymorphisms (e.g., rs72846714) in the NT5C2 gene associated with 6-MP metabolism in patients with ALL. However, the full spectrum of genetic variation in NT5C2 is unclear and its impact on 6-MP drug activation has not been comprehensively examined. To this end, we performed targeted sequencing of NT5C2 in 588 children with ALL and identified 121 single nucleotide polymorphisms nominally associated with erythrocyte TGN during 6-MP treatment (P < 0.05). Of these, 61 variants were validated in a replication cohort of 372 children with ALL. After considering linkage disequilibrium and multivariate analysis, we confirmed two clusters of variants, represented by rs72846714 and rs58700372, that independently affected 6-MP metabolism. Functional studies showed that rs58700372 directly altered the activity of an intronic enhancer, with the variant allele linked to higher transcription activity and reduced 6-MP metabolism (lower TGN). By contrast, rs72846714 was not located in a regulatory element and instead its association signal was explained by linkage disequilibrium with a proximal functional variant rs12256506 that activated NT5C2 transcription in-cis. Our results indicated that NT5C2 germline variation significantly contributes to interpatient variability in thiopurine drug disposition.

Topics: 5'-Nucleotidase; Adolescent; Alleles; Antimetabolites, Antineoplastic; Child; Child, Preschool; Cohort Studies; Erythrocytes; Female; Gene Expression Regulation, Neoplastic; Genome-Wide Association Study; Germ-Line Mutation; Humans; Linkage Disequilibrium; Male; Mercaptopurine; Multigene Family; Multivariate Analysis; Mutation, Missense; Polymorphism, Single Nucleotide; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Thioguanine; Young Adult

Topics: Adolescent; Adult; Aged; Allografts; Antigens, CD; Antigens, Neoplasm; Antineoplastic Combined Chemotherapy Protocols; Arabinonucleosides; Asparaginase; Bone Marrow; Cell Lineage; Combined Modality Therapy; Cyclophosphamide; Dexamethasone; Doxorubicin; Female; Hematopoietic Stem Cell Transplantation; Humans; Immunophenotyping; Male; Mercaptopurine; Methotrexate; Middle Aged; Mutation; Neoplasm Proteins; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Prodrugs; Progression-Free Survival; Proportional Hazards Models; Retrospective Studies; Survival Rate; Vincristine; Young Adult

NOTCH1/FBXW7 mutations trigger oncogenic NOTCH1 signaling and its downstream target genes play crucial roles in the molecular pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL). In the present study, NOTCH1 and FBXW7 mutations were studied in 25 primary T-ALL samples. All 34 exons of NOTCH1 and hotspot exons (exon 9 and exon 10) of FBXW7 were polymerase chain reaction amplified and sequenced for mutations. Our results showed that 13/25 (52%) were NOTCH1-mutated, of which 11 patients (44%) showed mutation in the hotspot exons. Four patients (16%) had mutations in non-hotspot exons of NOTCH1. Notably, 2 T-ALL patients (8%) harbored mutations in both hotspot and non-hotspot exons of NOTCH1, whereas 2 patients (8%) had mutations in the hotspot exons of FBXW7. In all, 7 mutations were identified which were not previously reported. The real-time polymerase chain reaction study in 15 patients revealed that increased expression of activated NOTCH1 was found in NOTCH1/FBXW7 hotspot exon-mutated cases. In addition, NOTCH1/FBXW7-mutated patients had showed upregulated HES1, c-MYC, NOTCH3 gene expression. When survival analysis was performed including samples (n=50) from our previous study, an early treatment response and better survival was observed in NOTCH1/FBXW7 hotspot-mutated patients. Our study suggests that NOTCH1/FBXW7 hotspot-mutated T-ALL cases had better response to ALL BFM-95 protocol.

Topics: Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Child; Child, Preschool; Cyclophosphamide; Cytarabine; DNA Mutational Analysis; F-Box-WD Repeat-Containing Protein 7; Female; Gene Expression Regulation, Neoplastic; Humans; India; Infant; Infant, Newborn; Male; Mercaptopurine; Methotrexate; Mutation; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Prognosis; Receptor, Notch1; Survival Analysis; Vincristine; Young Adult

Lymphoblastic lymphoma (LBL) is a rare form of non-Hodgkin's lymphoma (NHL). Cutaneous LBL is seen in less than 20% of patients.. Herein, we report the case of a 66-year-old male patient without any previous disease history of note and who was presenting a gradually spreading tumoral lesion of the scalp, several purplish macules and nodules on the trunk, and a single spinal adenopathy. A thoracic-abdominal-pelvic CT scan performed for acute renal failure, revealed extensive infiltration of retroperitoneal tissue. Skin biopsies and staging tests indicated LBL-T with associated cutaneous, bone and lymph node retroperitoneal lesions with no mediastinal mass. After two months of treatment with CHOP (four courses), the cutaneous lesions and abdominal tumoral mass had regressed and renal function had returned to normal.. There have been 13 reported cases of LBL with cutaneous involvement; most of these patients were young (under 30 years) and presented multiple cutaneous lesions (nodules or tumors) associated with numerous peripheral adenopathies, invasion of the bone marrow, and in many cases, a mediastinal mass. The clinical presentation of LBL-T in our case is novel on account of the cutaneous sites, associated with abdominal tumoral syndrome, without mediastinal infiltration, and with a single peripheral adenopathy, in an elderly subject.

Topics: Acute Kidney Injury; Aged; Antineoplastic Combined Chemotherapy Protocols; Bone and Bones; Cyclophosphamide; Doxorubicin; Humans; Immunophenotyping; Leukemic Infiltration; Lymph Nodes; Male; Mercaptopurine; Methotrexate; Organ Specificity; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Retroperitoneal Space; Skin; Vincristine

The aim of this study was to evaluate the outcomes using the dose-adjusted Berlin-Frankfurt-Munster (BFM-90) regimen without radiotherapy in adolescents and adults with T cell lymphoblastic lymphoma (T-LBL) at Beijing Cancer Hospital. Between March 2004 and December 2013, 57 newly diagnosed T-LBL patients were treated in our center. We retrospectively analyzed their main clinical characteristics and prognosis. The media age of the patients at diagnosis was 26 (range 14-54). At a median follow-up of 24 months (range 5-119), 38 patients (67 %) were alive. The estimated 3-year overall survival (OS) rate and progression-free survival (PFS) rate were 64 and 60 %, respectively. Abnormal WBC at diagnosis, high IPI and no early response were indicated as adverse prognostic factors for both PFS and OS (p < 0.05). There was also a trend for better survival in autologous peripheral blood stem cell transplantation (APBSCT) group as compared to non-APBSCT group (3-year OS 83 vs. 57 %), but without any significant difference. This study suggested that the dose-adjusted BFM-90 protocol without irradiation showed comparable long-term results in Chinese adolescents and adults with T-LBL. APBSCT may become a choice whether we can identify the best candidate.

Topics: Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Cyclophosphamide; Cytarabine; Daunorubicin; Dose-Response Relationship, Drug; Female; Follow-Up Studies; Humans; Male; Mercaptopurine; Middle Aged; Neoplasm Staging; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisolone; Prognosis; Retrospective Studies; Survival Rate; Vincristine; Young Adult

Individuals with decreased thiopurine methyltransferase (TPMT) activity are at risk of adverse effects of thiopurine administration whereas its increased activity may inactivate drugs faster. We evaluated genotype-phenotype correlations in patients with suspected hematological malignancies and inflammatory bowel disease from our region based on findings of nonlinear TPMT enzyme kinetics previously unreported.. The study group comprised 267 individuals. They were screened for the most common variants of low TPMT activity. TPMT activity was measured in erythrocytes using the HPLC rate-blanked method.. Thirty-three patients (12.4%) were heterozygous (26 were TPMT*1/*3A, 5 TPMT*1/*2, 2 TPMT *1/*3C) and 1 was a compound heterozygote (*2/*3A). Normal and low normal TPMT activities substantially overlapped in wild-type and heterozygous individuals, whereas high activities were found in 29 wild-type genotyped patients. Extreme and life-threatening toxicity was observed in the compound heterozygote patient.. Activity measurement performed at diagnosis provides clinicians with information on immediate pharmacokinetic-related adverse events and/or hypermetabolism, and genotyping may indicate the rate of pharmacodynamic thioguanine nucleotide accumulation due to slower overall thiopurine metabolism.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Chromatography, High Pressure Liquid; Cyclophosphamide; Cytarabine; Czech Republic; Daunorubicin; Erythrocyte Membrane; Female; Genetic Association Studies; Humans; Inflammatory Bowel Diseases; Male; Mercaptopurine; Methotrexate; Methyltransferases; Polymerase Chain Reaction; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Slovakia; Vincristine

Dramatic progress in the treatment of childhood acute lymphoblastic leukemia (ALL) has been achieved during the last two decades in Western countries, where the 5-year event-free survival (EFS) rate has risen from 30 to 85 %. However, similarly high cure rates have not always been achieved in all centers in developing countries due to limited sources. We evaluated the treatment results of the ALL-Berlin-Frankfurt-Münster (BFM) 95 protocol as used between 1995 and 2009 in the pediatric hematology departments of two university hospitals. A retrospective analysis of 343 children newly diagnosed with ALL (M/F 200/143, median age 6.8 years) was performed. The overall survival (OS) and EFS according to age, initial leukocyte count, immunophenotype, chemotherapy responses (on days 8, 15, and 33), and risk groups were analyzed by Kaplan-Meier survival analysis. Median follow-up time was 6.4 years. Complete remission was achieved in 97 % of children. Five-year EFS and OS were found to be 78.4 and 79.9 %, respectively. Children younger than 6 years old had significantly better EFS and OS (83.7 and 85.2 %) than children aged ≥6 years (71.4 and 72.8 %). Adolescents achieved 63 % EFS and 65 % OS. Patients who had initial leukocyte counts of <20 × 10(9)/L had better EFS and OS (82.2 and 84.6 %) than children with higher initial leukocyte counts (72.6 and 72.6 %). EFS for B-cell precursor and T-cell ALL was 81.5 and 66.7 %, respectively. Children with a good response to prednisolone on day 8 (87 %) achieved significantly better EFS and OS (81.2 and 81.9 % vs. 55.3 and 60.5 %). Children whose bone marrow on day 15 was in complete remission had higher EFS and OS (83.7 and 86.6.1 % vs. 56.4 and 61.5 %). Children in the standard-risk and medium-risk groups obtained statistically significantly higher EFS (95.5 and 82.7 %) and OS (97.7 and 82.3 %) compared to the high-risk group (EFS 56.3 %, OS 63.4 %). The relapse rate was 14.8 %. The median relapse time from diagnosis was 23.2 months. Death occurred in 69 of 343 patients (20.1 %). The major causes of death were infection and relapse. None of the patients died of drug-related toxicity. The ALL-BFM 95 protocol was applied successfully in these two centers. In developing countries in which minimal residual disease cannot be monitored, this protocol can still be used with high survival rates.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Child; Child, Preschool; Cyclophosphamide; Cytarabine; Daunorubicin; Disease-Free Survival; Drug Evaluation; Follow-Up Studies; Humans; Immunophenotyping; Infant; Kaplan-Meier Estimate; Leukocyte Count; Mercaptopurine; Oncogene Proteins, Fusion; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisolone; Remission Induction; Retrospective Studies; Risk Assessment; Risk Factors; Treatment Outcome; Turkey; Vincristine

Patients relapsing with T-cell acute lymphoblastic leukemia (T-ALL) face a dismal outcome. The aim of this study was to identify new markers of drug resistance and clinical response in T-ALL. We measured gene expression and drug sensitivity in 15 pediatric T-ALL cell lines to find signatures predictive of resistance to 10 agents used in therapy. These were used to generate a model for outcome prediction in patient cohorts using microarray data from diagnosis specimens. In three independent T-ALL cohorts, the 10-drug model was able to accurately identify patient outcome, indicating that the in vitro-derived drug-gene profiles were clinically relevant. Importantly, predictions of outcome within each cohort were linked to distinct drugs, suggesting that different mechanisms contribute to relapse. Sulfite oxidase (SUOX) expression and the drug-transporter ABCC1 (MRP1) were linked to thiopurine sensitivity, suggesting novel pathways for targeting resistance. This study advances our understanding of drug resistance in T-ALL and provides new markers for patient stratification. The results suggest potential benefit from the earlier use of 6-mercaptopurine in T-ALL therapy or the development of adjuvants that may sensitize blasts to this drug. The methodology developed in this study could be applied to other cancers to achieve patient stratification at the time of diagnosis.

Topics: Cell Line, Tumor; Child; Cohort Studies; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Follow-Up Studies; Gene Expression Profiling; Genetic Therapy; Humans; Mercaptopurine; Models, Statistical; Multidrug Resistance-Associated Proteins; Oligonucleotide Array Sequence Analysis; Pharmacogenetics; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Remission Induction; Sulfite Oxidase; Treatment Outcome

The BFM studies for relapsed childhood acute lymphoblastic leukemia (ALL) were started in 1983, at a time when cure rates for ALL were still lower and the number of children with ALL relapse equaled about the number of children with newly diagnosed neuroblastoma. Today, relapses have become relatively rare events in ALL although, because of the frequency of ALL, they are still a significant cause of death in children and adolescents. With currently used treatment modalities, cure rates of about 50% after relapse can be achieved, and, together with the improved results of front-line therapy, the survival rate of childhood ALL is now about 90%. Most children with extramedullary and late bone marrow (BM) relapses achieve a second CR; remission rates in patients with high-risk features, however, remain still unsatisfactory. With improved techniques allogeneic hematopoietic stem cell transplant (HSCT) has become a relatively safe treatment but is not necessary for all patients as postremission therapy. HSCT is not required in children with isolated extramedullary and late BM relapses with rapid response to induction therapy measured by molecular techniques (minimal residual disease, MRD) but absolutely indicated in patients with early BM relapses and systemic relapses of T-cell ALL. For patients with insufficient response innovative therapies such as small molecules or targeted immunological or pharmacological approaches are urgently required. Efforts have to be made, therefore, in order to detect potential biological or molecular targets, which can be used for individualized, more effective and hopefully less toxic therapies in the future.

Topics: Adolescent; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Bone Marrow; Child; Combined Modality Therapy; Cyclophosphamide; Cytarabine; Daunorubicin; Disease-Free Survival; Europe; Hematopoietic Stem Cell Transplantation; Humans; Mercaptopurine; Methotrexate; Multicenter Studies as Topic; Neoplasm, Residual; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Randomized Controlled Trials as Topic; Recurrence; Remission Induction; Retreatment; Survival Rate; Vincristine

Topics: Adult; Antineoplastic Combined Chemotherapy Protocols; Arabinonucleosides; Disease Progression; Fatal Outcome; Humans; Injections, Spinal; Male; Mediastinal Neoplasms; Mercaptopurine; Methotrexate; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Quadriplegia; Spinal Cord; Spinal Cord Diseases

The thiopurine antimetabolites, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are inactive pro-drugs that require intracellular metabolism for activation to cytotoxic metabolites. Thiopurine methyltransferase (TPMT) is one of the most important enzymes in this process metabolizing both 6-MP and 6-TG to different methylated metabolites including methylthioinosine monophosphate (meTIMP) and methylthioguanosine monophosphate (meTGMP), respectively, with different suggested pharmacological and cytotoxic properties. While meTIMP is a potent inhibitor of de novo purine synthesis (DNPS) and significantly contributes to the cytotoxic effects of 6-MP, meTGMP, does not add much to the effects of 6-TG, and the cytotoxicity of 6-TG seems to be more dependent on incorporation of thioguanine nucleotides (TGNs) into DNA rather than inhibition of DNPS. In order to investigate the role of TPMT in metabolism and thus, cytotoxic effects of 6-MP and 6-TG, we knocked down the expression of the gene encoding the TPMT enzyme using specifically designed small interference RNA (siRNA) in human MOLT4 leukemia cells. The knock-down was confirmed at RNA, protein, and enzyme function levels. Apoptosis was determined using annexin V and propidium iodide staining and FACS analysis. The results showed a 34% increase in sensitivity of MOLT4 cells to 1μM 6-TG after treatment with TPMT-targeting siRNA, as compared to cells transfected with non-targeting siRNA, while the sensitivity of the cells toward 6-MP was not affected significantly by down-regulation of the TPMT gene. This differential contribution of the enzyme TPMT to the cytotoxicity of the two thiopurines is probably due to its role in formation of the meTIMP, the cytotoxic methylated metabolite of 6-MP, while in case of 6-TG methylation by TPMT substantially deactivates the drug.

Topics: Antineoplastic Agents; Cell Line, Tumor; Humans; Mercaptopurine; Methyltransferases; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; RNA, Small Interfering; Thioguanine

Exposure of MOLT4 human T-cell leukemia cells to 6-Mercaptopurine (6-MP) and 6-Thioguanine (6-TG) resulted in acquired resistance associated with attenuated expression of the genes encoding concentrative nucleoside transporter 3 (CNT3) and equilibrative nucleoside transporter 2 (ENT2). To identify other alterations at the RNA and DNA levels associated with 6-MP- and 6-TG resistance, we compared here the patterns of gene expression and DNA copy number profiles of resistant sublines to those of the parental wild-type cells. The mRNA levels for two nucleoside transporters were down-regulated in both of the thiopurine-resistant sublines. Moreover, both of these cell lines expressed genes encoding the enzymes of purine nucleotide composition and synthesis, including adenylate kinase 3-like 1 and guanosine monophosphate synthetase at significantly lower levels than wild-type cells. In addition, expression of the mRNA for a specialized DNA polymerase, human terminal transferase encoded by the terminal deoxynucleotidyl transferase (DNTT) gene, was 122- and 93-fold higher in 6-TG- and 6-MP-resistant cells, respectively. The varying responses to 6-MP- and 6-TG observed here may help identify novel cellular targets and modalities of resistance to thiopurines, as well as indicating new potential approaches to individualization therapy with these drugs.

Topics: Antimetabolites, Antineoplastic; Cell Line, Tumor; DNA Nucleotidylexotransferase; Drug Resistance, Neoplasm; Gene Dosage; Gene Expression Profiling; Gene Expression Regulation, Leukemic; Humans; Mercaptopurine; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Thioguanine

Precursor T lymphoblastic lymphoma (T-LBL) is a highly aggressive lymphoma. Myeloid antigen expression was found in some of the patients, and its clinical significance is worth studying. This study was to compare the clinical features, short-term efficacy and survival of T-LBL patients with or without myeloid antigen expression so as to evaluate its prognostic significance.. Forty-five T-LBL patients, with a median age of 14 years, were treated at Sun Yet-sen University Cancer Center between January 2000 and July 2008. These patients were divided into myeloid antigen-positive group (My(+) group) and myeloid antigen-negative group (My(-) group) based on the flow cytometric (FCM) analysis in bone marrow or pleural fluid. Myeloid antigen expression and its correlation with the short-term efficacy and overall survival were assessed in the two groups.. There were 18 patients (40.0%) in the My(+) group and 27 (60.0%) in the My(-) group. The myeloid antigen expression was negatively correlated with the initial level of lactate dehydrogenase (LDH), but not with other clinical features. The remission rate was lower in the My(+) group than in the My(-) group (38.8% vs. 70.3%, P = 0.028). The 2-year overall survival rate was lower in the My(+) group than in the My(-) group (51.9% vs. 78.7%, P = 0.036). By age subgroup analysis, there were no differences in response and survival rate among children and adolescents with or without myeloid antigen expression. But the remission rate and the 2-year overall survival rate were significantly lower in adult patients with myeloid antigen expression than in patients without it. Univariate and multivariate analysis demonstrated that age and myeloid antigen expression were adverse prognostic factors.. Myeloid antigen expression is a predictor of a poor response to chemotherapy, and adverse prognostic factor in adult T-LBL, but not in children with T-LBL.

Topics: Adolescent; Adult; Age Factors; Aged; Antigens, CD7; Antigens, Differentiation, Myelomonocytic; Antineoplastic Combined Chemotherapy Protocols; Asparaginase; Child; Cyclin D3; Cyclophosphamide; Cytarabine; Daunorubicin; Doxorubicin; Etoposide; Female; Follow-Up Studies; Humans; Male; Mercaptopurine; Methotrexate; Middle Aged; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisone; Proportional Hazards Models; Remission Induction; Survival Rate; Transcription Factors; Vincristine; Young Adult

Topics: Adrenal Cortex Hormones; Adult; Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Arabinonucleosides; Asparaginase; Bone Marrow Diseases; Diagnosis, Differential; Doxorubicin; Humans; Ischemia; Leukemic Infiltration; Male; Mercaptopurine; Methotrexate; Myelitis, Transverse; Paraplegia; Paresthesia; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Recurrence; Salvage Therapy; Spinal Cord; Vincristine