Review article: monitoring for drug side-effects in inflammatory bowel disease.
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The side-effects suitable for monitoring in patients with inflammatory bowel disease being treated with the four main groups of drugs (5-aminosalicylic acid preparations, azathioprine and 6-mercaptopurine, methotrexate, and corticosteroids) are reviewed. On the basis of the reported frequency, severity and timing of side-effects, a practical scheme of monitoring is recommended. This includes a baseline measurement of full blood count, creatinine and liver function tests in all patients. In the absence of worrying symptoms, we recommend the following: (i) no monitoring for sulfasalazine; (ii) for other 5-aminosalicylic acid preparations, the measurement of creatinine at 6 and 12 months and then annually; (iii) for azathioprine/6-mercaptopurine, thiopurine methyltransferase genotype/phenotype determination has no role in treatment monitoring, but a full blood count at 2 weeks, 1 month, 3 months and then every 3 months should be performed; (iv) for methotrexate, a full blood count and liver function tests should be performed every 3 months; (v) for steroids, dual energy X-ray absorptiometry bone scanning should be performed at the start of therapy, every year in which steroids are used if the T score is < 0, and every 3-5 years if the T score is > 0. (+info)
Intensified and shortened cyclical chemotherapy for adult acute lymphoblastic leukemia.
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PURPOSE: To assess the efficacy and toxicity of a new treatment program of intensified and shortened cyclical chemotherapy (protocol 8707) in adults with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Previously untreated adults < or = 60 years old with ALL were treated with a four-agent induction chemotherapy regimen. This was followed by cyclical postremission therapy with high-dose cytarabine/etoposide; high-dose methotrexate/6-mercaptopurine; and daunorubicin, vincristine, prednisone, and asparaginase. Maintenance chemotherapy with oral methotrexate and 6-mercaptopurine was continued for 30 months. CNS prophylaxis was given with intrathecal methotrexate in addition to the systemic chemotherapy indicated above. RESULTS: Seventy-eight of 84 patients (93%) achieved complete remission. With a median follow-up of 5.6 years, 5-year event-free survival (EFS) of all remission patients is 52%. Patients with high-risk features including adverse cytogenetics, failure to achieve remission with the first cycle of chemotherapy, and B-precursor disease with WBC counts more than 100,000/microL all relapsed unless taken off study for transplantation. For patients without these high-risk features, 5-year EFS was 60%. Compared with our previous treatment regimen, results appear to be improved for patients with standard-risk B-precursor disease (5-year EFS, 66% v 34%; P =.01). CONCLUSION: Intensified and shortened chemotherapy may improve the outcome for patients with ALL with B-precursor disease lacking high-risk features. Further trials of this regimen are warranted. (+info)
BFM-oriented treatment for children with acute lymphoblastic leukemia without cranial irradiation and treatment reduction for standard risk patients: results of DCLSG protocol ALL-8 (1991-1996).
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Modern treatment strategies, consisting of intensive chemotherapy and cranial irradiation, have remarkably improved the prognosis for children with acute lymphoblastic leukemia. However, patients with a potential for cure are at risk of severe acute and late adverse effects of treatment. Furthermore, in 25-30% of patients treatment still fails. The objectives of the DCLSG study ALL 8 were to decrease the toxicity and to increase the effectivity of BFM-oriented treatment. Decrease of toxicity was aimed at by confirmation of the results of the previous DCLSG study ALL-7, showing that the majority (94%) of children with ALL can successfully be treated with BFM-oriented therapy without cranial irradiation, and by reduction of treatment for standard risk (SRG) patients. To increase the cure rate in medium risk (MRG) patients the efficacy of high doses of intravenous 6-mercaptopurine (HD-6MP) during protocol M and in SRG patients the efficacy of high doses of L-asparaginase (HD-L-ASP) during maintenance treatment was studied in randomized studies. Patient stratification and treatment were identical to protocol ALL-BFM90, with the following differences: no prophylactic cranial irradiation, SRG patients received only phase 1 of protocol I. Four hundred and sixty-seven patients entered the protocol: 170 SRG, 241 MRG and 56 HRG patients. The 5 years event-free survival rate for all patients was 73% (s.e. 2%); for SRG, MRG and HRG patients 85% (s.e. 3%), 73% (s.e. 3%) and 39% (s.e. 7%), respectively. In patients >1 year of age at diagnosis unfavorable prognostic factors were male sex, >25% blasts in the bone marrow at day 15 and initial white blood cell count (WBC) >50 x 10(9)/l. The cumulative risk of CNS relapse rate was 5% (s.e. 1%) at 5 years. These results confirm that the omission of cranial irradiation in BFM-oriented treatment does not jeopardize the overall good treatment results, nor does early reduction of chemotherapy in SRG patients. No benefit was observed from treatment intensification with HD-L-ASP in SRG patients, nor from HD-6MP in MRG patients. (+info)
Affinity labelling to - SH groups in adenosine - triphosphate - phosphoribosyl transferase with the dinitrophenyl group from S-dinitrophenyl-6-mercaptopurine-riboside 5'-phosphate.
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Adenosine-triphosphate-phosphoribosyl transferase from Escherichia coli reacts with S-dinitrophenyl-6-mercaptopurine-riboside 5'-phosphate. In this reaction the dinitrophenyl group becomes attached to the enzyme, while the nucleotide is split off. Most aliphatic high and low-molecular-weight-SH compounds react with the thioether in the opposite way, i.e. bind the nucleotide and split off dinitrothiophenol. It appears that the dinitrophenyl moiety of the thioether interacts with the enzyme in a specific way, and that this interaction activates the bond between the dinitrophenyl group and the sulfur atom. In support of this it was found that dinitrophenol inhibits the transferase reaction with half maximal effect at 0.4 mM. The inhibition is competitive with ATP. Dinitrophenol also competes with ATP in binding studies. (+info)
Impact of addition of maintenance therapy to intensive induction and consolidation chemotherapy for childhood acute myeloblastic leukemia: results of a prospective randomized trial, LAME 89/91. Leucamie Aique Myeloide Enfant.
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PURPOSE: To determine whether the use of maintenance therapy (MT) delivered after intensive induction and consolidation therapy confers any advantage in childhood acute myeloid leukemia (AML). PATIENTS AND METHODS: A total of 268 children with AML were registered in the Leucamie Aique Myeloide Enfant (LAME) 89/91 protocol. This regimen included an intensive induction phase (mitoxantrone plus cytarabine) and, for patients without allograft, two consolidation courses, one containing timed-sequential high-dose cytarabine, asparaginase, and amsacrine. In the LAME 89 pilot study, patients were given an additional MT consisting of mercaptopurine and cytarabine for 18 months. In the LAME 91 trial, patients were randomized to receive or not receive MT. RESULTS: A total of 241 (90%) of 268 patients achieved a complete remission. The overall survival and event-free survival at 6 years were 60% +/- 6% and 48% +/- 6%, respectively. For the complete responders after consolidation therapy, the 5-year disease-free survival was not significantly different in MT-negative and in MT-positive randomized patients (respectively, 60% +/- 19% v 50% +/- 15%; P =.25), whereas the 5-year overall survival was significantly better in MT-negative randomized patients (81% +/- 13% v 58% +/- 15%; P =.04) due to a higher salvage rate after relapse. CONCLUSION: More than 50% of patients can be cured of AML in childhood. Either drug intensity or each of the induction and postremission phases may have contributed to the outstanding improvement in outcome. Low-dose MT is not recommended. Exposure to this low-dose MT may contribute to clinical drug resistance and treatment failure in patients who experience relapse. (+info)
The effect of thiopurine methyltransferase expression on sensitivity to thiopurine drugs.
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Although the thiopurine drugs 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are well established agents for the treatment of leukemia, controversies remain regarding their main mode of action. Previous evidence has suggested that although 6-TG exerts a cytotoxic effect through incorporation of 6-thioguanine nucleotides into newly synthesized DNA (DNA-TGN), an important component of the mode of action of 6-MP is inhibition of purine de novo synthesis (PDNS) through the production of S-methyl-thioinosine 5'-monophosphate (MeTIMP), not formed in cells exposed to 6-TG. We have shown that thiopurine methyltransferase (TPMT) modulates this effect. By transfection of the human TPMT gene using an inducible system to produce a 3.8-fold increase in TPMT activity in the ecdysone receptor 293 embryonic kidney cell line, we demonstrated a 4.4-fold increase in sensitivity to 6-MP. This was associated with a rise in intracellular levels of MeTIMP but a decrease in levels of DNA-TGN. In contrast, induction of TPMT produced a 1.6-fold decrease in sensitivity to 6-TG, a decrease in levels of DNA-TGN, and an increase in levels of methylated thioguanosine monophosphate. Exposure of cells to equitoxic doses of drug showed similar incorporation of DNA-TGN for 6-TG but for 6-MP significantly reduced DNA-TGN in TPMT-induced compared with uninduced cells. For equitoxic doses of 6-MP, equivalent levels of MeTIMP correlated with equivalent amounts of PDNS. These observations suggest that intracellular TGN levels do not give an accurate reflection of cytotoxic potential in patients treated with 6-MP, because different levels of DNA-TGN may be associated with equitoxic effects. (+info)
TPMT in the treatment of Crohn's disease with azathioprine.
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Azathioprine induced profound myelosuppression linked to TPMT deficiency has now been documented in many patient groups, including those with Crohn's disease. At the start of azathioprine or mercaptopurine therapy, measurement of TPMT activity has a role in identifying the 1 in 300 patients who are at risk of severe myelosuppression when treated with standard thiopurine dosages. During the initial months of azathioprine therapy a knowledge of TPMT status warns of early bone marrow toxicity. In patients established on azathioprine these is no clear evidence to suggest that TPMT is predictive of clinical response or drug toxicity, indicating a role for TPMT in the prediction of early events rather than long term control. In patients with Crohn's disease on long term azathioprine therapy, it is clear that myelosuppression, particularly leucopenia, is caused by other factors in addition to variable TPMT activity and therefore monitoring of blood cell counts throughout treatment is essential. (+info)
De novo purine synthesis inhibition and antileukemic effects of mercaptopurine alone or in combination with methotrexate in vivo.
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Methotrexate (MTX) and mercaptopurine (MP) are widely used antileukemic agents that inhibit de novo purine synthesis (DNPS) as a mechanism of their antileukemic effects. To elucidate pharmacodynamic differences among children with acute lymphoblastic leukemia (ALL), DNPS was measured in leukemic blasts from newly diagnosed patients before and after therapy with these agents. Patients were randomized to receive low-dose MTX (LDMTX: 6 oral doses of 30 mg/m(2)) or high-dose MTX (HDMTX: intravenous 1 g/m(2)) followed by intravenous MP; or intravenous MP alone (1 g/m(2)), as initial therapy. At diagnosis, the rate of DNPS in bone marrow leukemia cells was 3-fold higher in patients with T-lineage ALL compared with those with B-lineage ALL (769 +/- 189 vs 250 +/- 38 fmol/nmol/h; P =.001). DNPS was not consistently inhibited following MP alone but was markedly inhibited following MTX plus MP (median decrease 3% vs 94%; P <.001). LDMTX plus MP and HDMTX plus MP produced greater antileukemic effects (percentage decrease in circulating leukocyte counts) compared with MP alone (-50% +/- 4%, -56% +/- 3%, and - 20% +/- 4%, respectively; P <.0001). Full DNPS inhibition was associated with greater antileukemic effects compared with partial or no inhibition (-63% +/- 4% vs -37% +/- 4%; P <.0001) in patients with nonhyperdiploid B-lineage and T-lineage ALL. HDMTX plus MP yielded 2-fold higher MTX polyglutamate concentrations than LDMTX plus MP (2148 +/- 298 vs 1075 +/- 114 pmol/10(9) cells; P <.01) and a higher percentage of patients with full DNPS inhibition (78% vs 53%; P <.001). Thus, the extent of DNPS inhibition was related to in vivo antileukemic effects, and a single dose of intravenous MP produced minimal DNPS inhibition and antileukemic effects, whereas MTX plus MP produced greater antileukemic effects and DNPS inhibition, with full inhibition more frequent after HDMTX. (+info)