Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As a part of a pilot clinical study, a high-performance reversed-phase liquid chromatography analysis was developed to quantify temozolomide in plasma and urine of patients undergoing a chemotherapy cycle with temozolomide. All samples were immediately stabilized with 1 M HCl (1 + 10 of biological sample), frozen and stored at -20 degrees C prior to analysis. The clean-up procedure involved a solid-phase extraction (SPE) of clinical sample (100 microliters) on a 100-mg C18-endcapped cartridge. Matrix components were eliminated with 750 microliters of 0.5% acetic acid (AcOH). Temozolomide was subsequently eluted with 1250 microliters of methanol (MeOH). The resulting eluate was evaporated under nitrogen at RT and reconstituted in 200 microliters of 0.5% AcOH and subjected to HPLC analysis on an ODS-column (MeOH-0.5% AcOH, 10:90) with UV detection at 330 nm. The calibration curves were linear over the concentration range 0.4-20 micrograms/ml and 2-150 micrograms/ml for plasma and urine, respectively. The extraction recovery of temozolomide was 86-90% from plasma and 103-105% from urine over the range of concentrations considered. The stability of temozolomide was studied in vitro in buffered solutions at RT, and in plasma and urine at 37 degrees C. An acidic pH (< 5-6) should be maintained throughout the collection, the processing and the analysis of the sample to preserve the integrity of the drug. The method reported here was validated for use in a clinical study of temozolomide for the treatment of metastatic melanoma and high grade glioma.
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PMID:Determination of temozolomide in human plasma and urine by high-performance liquid chromatography after solid-phase extraction. 766 2

The activity of 8-carbamoyl-3-methylimidazo[5,1-d]-1,2,3,5-tetrazin- 4(3H)-one (temozolomide) in the treatment of a panel of xenografts derived from ependymoma, medulloblastoma, and childhood and adult high-grade glioma was evaluated in athymic nude mice bearing s.c. and intracranial tumors. Temozolomide administered daily for a total of five doses demonstrated marked activity against a panel of Mer+ xenografts despite marginal to moderate activity of 1,3-bis(2-chloroethyl)-1-nitrosourea. The growth delays produced by temozolomide in these xenografts were 1.8-7.5-fold greater than those produced by procarbazine. Although temozolomide demonstrated marginal activity against the Mer+ cell line D341 Med when a 5-day schedule was used, a high-dose 1-day schedule resulted in moderate activity. Temozolomide produced increases in median survival of 1285% (adult glioma D-54 MG), 323% (childhood glioma D-456 MG), and 68% (ependymoma D612 EP). Pretreatment of mice with O6-benzylguanine increased temozolomide-induced mortality, requiring reduction of the dosage from 1200 to 750 mg/m2 on the single-day regimen. O6-Benzylguanine pretreatment of mice bearing Mer+ D341 Med increased the growth delay of temozolomide, in duplicate experiments, from -3.1 to 4.8 and 1.1 to 4.9 days. These studies suggest that temozolomide may be active in the treatment of a broad spectrum of central nervous system cancers, including Mer+ tumors resistant to 1,3-bis(2-chloroethyl)-1-nitrosourea.
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PMID:Activity of temozolomide in the treatment of central nervous system tumor xenografts. 779 12

Temozolomide (8-carbamoyl-3-methylimidazo[5,1-d]-1,2,3,5-tetrazin-4-(3H)-one) has shown promising activity in Phase I trials against some brain (glioma) and skin (melanoma, mycosis fungoides) cancers. Temozolomide and lomustine (CCNU) showed parallel toxicity in seven human tumour cell lines and this generally correlated (correlation coefficients 0.87 and 0.92 respectively) with the level of expression of the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase, EC 2.1.1.63). Pretreating cells with the ATase inhibitor, O6-benzylguanine (BG), potentiated cytotoxicity to a similar degree with both drugs, but did not sensitise a cell line (ZR-75-1) expressing very low levels of this protein. When BG pretreatment was combined with repeat doses of temozolomide a dramatic potentiation (300 fold) was seen in MAWI cells, which express high levels of ATase, but not in a cell line (U373) expressing lower levels of ATase. [14C]-labelled temozolomide uptake was similar in sensitive and resistant lines. Human ATase-cDNA transfected xeroderma pigmentosum (XP) fibroblasts were more resistant than XP control cells to temozolomide and the related chloroethylating agent mitozolomide and although BG completely suppressed ATase activity in these cells, resistance was still greater than in control cells.
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PMID:Depletion of O6-alkylguanine-DNA alkyltransferase correlates with potentiation of temozolomide and CCNU toxicity in human tumour cells. 851 14

Temozolomide, a new oral cytotoxic agent, was given to 75 patients with malignant gliomas. The schedule used was for the first course 150 mg/m2 per day for 5 days (i.e. total dose 750 mg/m2), escalating, if no significant myelosuppression was noted on day 22, to 200 mg/m2 per day for 5 days (i.e. total dose 1000 mg/m2) for subsequent courses at 4-week intervals. There were 27 patients with primary disease treated with two courses of temozolomide prior to their radiotherapy and 8 (30%) fulfilled the criteria for an objective response. There were 48 patients whose disease recurred after their initial surgery and radiotherapy and 12 (25%) fulfilled the criteria for an objective response. This gave an overall objective response rate of 20 (27%) out of 75 patients. Temozolomide was generally well tolerated, with little subjective toxicity and predictable myelosuppression. However, the responses induced with this schedule were of short duration and had relatively little impact on overall survival. In conclusion, temozolomide given in this schedule has activity against high grade glioma. However, studies evaluating chemotherapy in primary brain tumours should include a quality-of-life/performance status evaluation in addition to CT or MRI scanning assessment.
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PMID:The Charing Cross Hospital experience with temozolomide in patients with gliomas. 903 4

The in vitro cytotoxicity of 8-carbamoyl-3-methylimidazo [5,1-d]-1,2,3,5-tetrazine-4(3H)-one (temozolomide) with concurrent X-irradiation was examined in a human glioblastoma cell line (U373MG) as a potential radio-chemotherapeutic treatment for malignant glioma. The combination was also examined in a human colorectal adenocarcinoma (Mawi) which had 100-fold greater O6-alkylguanine-DNA alkyltransferase (AGT) activity, a DNA-repair protein which confers resistance to temozolomide. A comparison of IC50 values indicated U373MG to be over 32-fold more sensitive to temozolomide than Mawi, but slightly more resistant to X-irradiation (p < 0.035; unpaired two-tailed t-test). Temozolomide and X-irradiation proved largely additive in U373MG by isobologram analysis (50% iso-effect) and the addition of 10 microM temozolomide to 1-2 Gy of X-irradiation increased cell kill by 2.5- to 3.0-fold. However, the combination was antagonistic in Mawi: an effect attributed to AGT induction by X-irradiation as the antagonism was removed by co-incubation with the AGT inhibitor O6-benzylguanine (O6-BG 1 microM; 24 h). O6-BG did not affect the radiation dose-response curve, but significantly increased temozolomide cytotoxicity (p < 0.015). In conclusion, the combination of temozolomide with radiation is at best additive, but could nonetheless by of considerable therapeutic benefit in glioma, particularly if administered for prolonged periods. If AGT induction compromises the efficacy of this therapy, it may be circumvented with an appropriate inhibitor such as O6-BG.
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PMID:In vitro evaluation of temozolomide combined with X-irradiation. 914 18

Temozolomide (SCH 52365) is an imidazotetrazine derivative which exhibits broad spectrum activity against murine tumors and is structurally related to dacarbazine (DTIC). Temozolomide cytotoxicity is schedule dependent in vivo with a daily x 5 schedule showing the highest activity. Oral temozolomide is rapidly and completely absorbed with minimal interpatient and intrapatient variability in pharmacokinetics. Clinical studies have demonstrated activity against melanoma and glioma. The present study examined the activity of oral temozolomide against patients with pancreatic cancer. Patients with advanced pancreatic adenocarcinoma previously untreated with chemotherapy received temozolomide 200 mg/m2/day once daily orally for 5 days with cycles repeated every 28 days. There were 16 patients entered on study with 15 evaluable for response and toxicity. There were no responses seen in 15 evaluable patients with 14 manifesting progressive disease within 2 months of starting therapy. Toxicity was primarily hematological with 3 patients experiencing > or = grade 3 neutropenia and thrombocytopenia respectively. Other toxicities were relatively modest. In conclusion, temozolomide in the once daily x 5 schedule is inactive against adenocarcinoma of the pancreas.
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PMID:A phase II study of temozolomide in advanced untreated pancreatic cancer. 974 May 47

Temozolomide, a methylating imidazotetrazinone, has antitumor activity against gliomas, malignant melanoma, and mycosis fungoides and is presently administered as a 5-day oral schedule every 4 weeks. This Phase I study aimed to determine the maximum tolerated dose of temozolomide administered as a single oral daily dose for a continuous 6- or 7-week period, evaluate the plasma pharmacokinetics on this schedule, and compare total plasma exposure over 7 weeks with the conventional 5-day regimen. Twenty-four patients with varying tumor types (17 of 24 gliomas) received temozolomide. All had clinically evaluable, refractory disease; normal renal, hepatic, and bone marrow function; and WHO performance status < or = 2. Temozolomide was administered at 50 mg/m2/day, increasing by 25 mg/m2/day/cohort until at 100 mg/m2/day grade 4 myelotoxicity forced dose reductions to 85 mg/m2/day, then 75 mg/m2/day. At 75 mg/m2/day the regimen was extended to 7 weeks, allowing the future potential combination with irradiation for primary gliomas. Patient responses (standard Union International Contre Cancer criteria; for gliomas objective response) and toxicity were assessed. Temozolomide plasma pharmacokinetics were determined on day 1 and at the beginning of the final week of administration (n = 5). The most frequent toxicities were myelosuppression and grades 1 and 2 nausea and vomiting. Grade 4 leucopenia and thrombocytopenia occurred in one of four patients receiving 100 mg/m2/day temozolomide and in one of seven patients receiving 85 mg/m2/day. These hematological toxicities did not exceed grade 2 in 10 patients receiving 75 mg/m2/day temozolomide. One of 4 malignant melanoma patients and 7 of 17 glioma patients (41%) demonstrated tumor responses. The overall response rate for this prolonged schedule was 33% (objective response, 7 of 24 patients; partial response, 1 of 24 patients); also, 6 of 17 glioma patients maintained SD. Peak plasma temozolomide concentrations were obtained 30-90 min after oral administration. Elimination in plasma was best described by a monoexponential equation with an elimination half-life of 96 +/- 16 min. No plasma accumulation of temozolomide occurred. Toxicity was greatest in higher dose cohorts, with a resultant maximum tolerated dose of 85 mg/m2/day, whereas lower dose cohorts tolerated the schedule well. The area under the temozolomide plasma versus time curve was noncumulative between the first and last week of the schedule. Temozolomide administration of 75 mg/m2/day over a 7-week period permits a 2.1-fold greater drug exposure/4 weeks in comparison with the 5-day schedule of 200 mg/m2/day repeated every 28 days. The overall response rate was 33% (glioma patients, 41% and a further 25% SD). Temozolomide (75 mg/m2/day) for 7 weeks is the recommended starting dose for further assessment of this schedule.
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PMID:Phase I trial of temozolomide using an extended continuous oral schedule. 976 65

Temozolomide (TMZ) is a new imidazotetrazine derivative with early clinical activity in glioma and melanoma. The purpose of this Phase I study is to characterize the toxicity, pharmacokinetics, and antitumor activity of TMZ administered on an oral 5-day schedule to patients with or without prior exposure to nitrosourea (NU). Thirty-six eligible patients received a total of 77 cycles of therapy with TMZ administered p.o. at doses ranging from 50 mg/m2/day to 250 mg/m2/day for 5 days, every 4 weeks. Separate dose escalations were carried out in patients, with or without prior exposure to NU. Pharmacokinetic studies were performed during the first cycle of treatment on days 1 and 5. Dose-limiting toxicity was thrombocytopenia, and the maximally tolerated doses for patients with and without prior exposure to NU were 150 mg/m2/day for 5 days (total dose, 750 mg/m2) and 250 mg/m2/day for 5 days (total dose, 1250 mg/m2), respectively. Significant (grade 3 or higher) thrombocytopenia was observed in six patients during cycle 1. The median times to nadir and recovery were 17 and 15 days, respectively. Nonhematological toxicity was generally manageable and consisted of fatigue, nausea, and vomiting. There were two complete responses (one glioma and one melanoma) in patients without prior NU. No objective responses were seen in patients with prior NU treatment. Pharmacokinetic studies showed rapid absorption with a mean time to peak concentration of 60 min and mean t1/2 of 109 min (range, 80-121 min). The area under the curve and the peak plasma concentrations were linear over the dose range of 50-250 mg/m2/day. The mean apparent oral clearances on day 1 for patients with and without prior NU exposure were 102+/- 27 and 115+/- 22 ml/min/m2, respectively. Apparent oral clearances on days 1 and 5 were found to differ with respect to NU exposure (P = 0.047). Renal clearance of the parent drug and its metabolism to 3-methyl-2, 3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxylic acid were minor pathways of TMZ elimination. We conclude that TMZ is well tolerated in this oral 5-day schedule with dose-limiting thrombocytopenia and that it has promising activity in glioma and melanoma. The recommended doses for Phase II studies in patients with and without prior NU are 125 mg/m2/day for 5 days and 225 mg/m2/day for 5 days, respectively.
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PMID:Phase I trial of temozolomide (NSC 362856) in patients with advanced cancer. 981 88

Temozolomide, an oral cytotoxic agent with approximately 100% bioavailability after one administration, has demonstrated schedule-dependent clinical activity against highly resistant cancers. Thirty patients with minimal prior chemotherapy were enrolled in this phase I trial to characterize the drug's safety, pharmacokinetics and anti-tumour activity, as well as to assess how food affects oral bioavailability. To determine dose-limiting toxicities (DLT) and the maximum tolerated dose (MTD), temozolomide 100-250 mg m(-2) was administered once daily for 5 days every 28 days. The DLT was thrombocytopenia, and the MTD was 200 mg m(-2) day(-1). Subsequently, patients received the MTD to study how food affects the oral bioavailability of temozolomide. When given orally once daily for 5 days, temozolomide was well tolerated and produced a non-cumulative, transient myelosuppression. The most common non-haematological toxicities were mild to moderate nausea and vomiting. Clinical activity was observed against several advanced cancers, including malignant glioma and metastatic melanoma. Temozolomide demonstrated linear and reproducible pharmacokinetics and was rapidly absorbed (mean Tmax approximately 1 h) and eliminated (mean t1/2 = 1.8 h). Food produced a slight reduction (9%) in absorption of temozolomide. Temozolomide 200 mg m(-2) day(-1) for 5 days, every 28 days, is recommended for phase II studies.
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PMID:Phase I dose-escalation and pharmacokinetic study of temozolomide (SCH 52365) for refractory or relapsing malignancies. 1057 60

Glioblastoma multiforme and anaplastic astrocytoma are the most common primary central nervous system malignancies and are the major cause of morbidity/ mortality despite combined modality approaches. Temozolomide (TMZ), a novel, oral, second-generation alkylating agent, has demonstrated antitumor activity against a broad range of solid tumors and highly resistant malignancies, including high-grade glioma Temozolomide does not require hepatic metabolism for activation, rapidly penetrates the cerebrospinal fluid, and consistently demonstrates reproducible linear pharmacokinetics with approximately 100% oral bioavailability. In preliminary clinical studies, TMZ has demonstrated meaningful efficacy and an acceptable safety profile in the treatment of patients with malignant glioma. These results have been recently confirmed in three open-label, multi-institutional studies that evaluated the use of TMZ in 525 malignant glioma patients. These studies represent the largest evaluation of a single agent in patients with recurrent malignant gliomas and were rigorously controlled with strict, prospectively defined criteria for assessment of tumor response, central review of histology, and validated instruments to assess health-related quality of life. Temozolomide was effective in delaying disease progression and maintaining health-related quality of life. Temozolomide represents a promising new agent in the treatment of malignant glioma.
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PMID:Temozolomide in malignant gliomas. 1086 47


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