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)

Temozolomide is a novel, oral, second-generation alkylating agent. Preclinical and phase I/II studies have demonstrated its efficacy against newly diagnosed high-grade glioma and anaplastic astrocytoma. Its antineoplastic effect is accompanied by quality of life benefits in patients with these debilitating tumors. Neoplastic meningitis, a refractory disorder, develops in approximately 3% to 8% of patients with systemic cancers. Traditional approaches to leptomeningeal metastases, such as radiation and intrathecal chemotherapy, have limited success and a high degree of toxicity. Temozolomide offers a number of potential therapeutic advantages in this disorder, including activity against a wide spectrum of human cancers that produce neoplastic meningitis and penetration of the blood-brain barrier. Patients treated with temozolomide benefit from both its systemic and intracranial activity. Recently, intrathecal temozolomide has been shown to increase median survival in athymic rats bearing subarachnoid human malignant glioma xenografts. Its efficacy, convenient dosing, and predictable safety profile make it an ideal agent for future study of these difficult-to-treat central nervous system malignancies.
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PMID:Temozolomide in early stages of newly diagnosed malignant glioma and neoplastic meningitis. 1086 48

Temozolomide (SCHS2.365), an oral alkylating agent which penetrates the blood-brain barrier, evolved as an alternative to dacarbazine. The aim of this study was to evaluate the efficacy and safety of temozolomide in terms of overall survival, progression-free survival, clinical benefit and health related quality of life in symptomatic patients with relapsing malignant glioma and a poor performance status. Eleven patients were enrolled in the study. The median age was 44.6 years. Patients were treated with temozolomide per os at a dose of 150-200 mg/m2 daily for 5 consecutive days. Each cycle was repeated every 28 days. The median number of courses given per patient was 3.5. Nine patients were assessable for response. All patients were evaluable for toxicity. Based on radiographic findings 4 patients had stable disease (2 patients after a total of 16 cycles, and 2 patients after a total of 10 cycles). Four patients had progressive disease after 2 to 4 cycles. Of these 3 patients demonstrated a clinical benefit and one patient died after 3 cycles of treatment. Six patients had a significant clinical benefit even after 2 cycles of treatment with improvement of their neurological and performance status. Hematologic toxicity Gr II-III occurred in 3/9 patients. Nonhematologic toxicity consisted of Gr I nausea, and vomiting. In conclusion temozolomide appears to be a useful alternative for patients with relapsing malignant glioma after radiation and surgery and a poor performance status with little or no toxicity and considerable clinical benefit.
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PMID:Phase II study of temozolomide in patients with relapsing high grade glioma and poor performance status. 1087 15

Malignant gliomas (glioblastoma multiforme and anaplastic astrocytoma) occur more frequently than other types of primary central nervous system tumors, having a combined incidence of 5-8/100,000 population. Even with aggressive treatment using surgery, radiation, and chemotherapy, median reported survival is less than 1 year. Temozolomide, a new drug, has shown promise in treating malignant gliomas and other difficult-to-treat tumors. Temozolomide, a p.o. imidazotetrazine second-generation alkylating agent, is the leading compound in a new class of chemotherapeutic agents that enter the cerebrospinal fluid and do not require hepatic metabolism for activation. In vitro, temozolomide has demonstrated schedule-dependent antitumor activity against highly resistant malignancies, including high-grade glioma. In clinical studies, temozolomide consistently demonstrates reproducible linear pharmacokinetics with approximately 100% p.o. bioavailability, noncumulative minimal myelosuppression that is rapidly reversible, and activity against a variety of solid tumors in both children and adults. Preclinical studies have evaluated the combination of temozolomide with other alkylating agents and inhibitors of the DNA repair protein O6-alkylguanine alkyltransferase to overcome resistance to chemotherapy in malignant glioma and malignant metastatic melanoma. Temozolomide has recently been approved in the United States for the treatment of adult patients with refractory anaplastic astrocytoma and, in the European Union, for treatment of glioblastoma multiforme showing progression or recurrence after standard therapy. Predictable bioavailability and minimal toxicity make temozolomide a candidate for a wide range of clinical testing to evaluate the potential of combination treatments in different tumor types. An overview of the mechanism of action of temozolomide and a summary of results from clinical trials in malignant glioma are presented here.
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PMID:Temozolomide and treatment of malignant glioma. 1091 98

Temozolomide, an imidazole tetrazinone, and CPT-11, a camptothecin derivative, have previously been shown to have anti-central nervous system tumor activity in laboratory and clinical studies. The current experiments were designed to evaluate the activity of temozolomide plus CPT-11 against a malignant glioma-derived xenograft, D-54 MG, growing s.c. in athymic nude mice. The initial schedule of i.p. drug administration was temozolomide at 0.1 LD10 on day 1 and CPT-11 at 0.1 LD10 on days 1-5 and 8-14. The combination of these two agents produced greater than additive activity against D-54 MG. This enhanced activity was maintained when the initial administration of CPT-11 was delayed to day 3 or day 5. However, when CPT-11 was administered first on day 1 using 0.5 LD10 (for the single dose schedule) followed by temozolomide (0.1 LD10) 5 h, 3 days, or 5 days later, the enhancement of activity was substantially reduced. These results demonstrate that the combination of temozolomide plus CPT-11 displays a schedule-dependent enhancement of antitumor activity, suggest a mechanistic explanation for the enhanced activity, and provide the rationale for a Phase I trial of this regimen.
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PMID:Schedule-dependent activity of temozolomide plus CPT-11 against a human central nervous system tumor-derived xenograft. 1105 Dec 70

Expression of iNOS in glioma and other tumors has been extensively documented but the effects of NO derived from iNOS on tumor-killing mechanisms of chemotherapy drugs remain to be fully defined. We note that increased NO synthesis by cytokine exposure or iNOS overexpression neutralized the cytotoxicity of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), but not cisplatin, in rat C6 glioma cells. Suppression of BCNU cytotoxicity associated with iNOS overexpression could be abolished by pharmacological inhibition of NOS or coexpression of an antisense RNA against iNOS. Both BCNU and CCNU are chloroethylnitrosoureas that kill tumor cells via carbamoylating and alkylating actions. Further studies using compounds that each carry these different activities indicate that iNOS neutralized carbamoylating, but not alkylating, action of chloroethylnitrosoureas. Temozolomide, a novel chemotherapy drug recently available for treating brain tumors, carries only alkylating, but not carbamoylating, action. Overexpression of iNOS in C6 cells failed to neutralize temozolomide cytotoxicity. Results from the present study demonstrate the ability of iNOS-derived NO to confer chemoresistance against the carbamoylating potential of chloroethylnitrosoureas in vitro. Further investigation is needed to test whether iNOS expression, frequently noted in malignant brain tumors, also enhances chemoresistance against chloroethylnitrosoureas in vivo.
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PMID:Inducible nitric oxide synthase neutralizes carbamoylating potential of 1,3-bis(2-chloroethyl)-1-nitrosourea in c6 glioma cells. 1125 58

Temozolomide (TMZ) is a DNA-methylating agent that has recently been introduced into Phase II and III trials for the treatment of gliomas. TMZ produces O6-methylguanine in DNA, which mispairs with thymine during the next cycle of DNA replication. Subsequent futile cycles of DNA mismatch repair can lead to a p53-associated apoptotic cell death, although this mechanism has been described mostly in hematopoietic neoplasms. We studied the action of TMZ in gliomas and the role p53 might play by using U87 glioma cells that were either p53-wild-type or p53-deficient (by virtue of expression of the viral oncoprotein E6). LN-Z308 cells, in which p53 gene is deleted, were also used. p53-proficient U87 MG cells underwent a prolonged, p53- and p21(Waf1/Cip1)-associated G2-M arrest beginning 2 days after TMZ treatment. Although very few of these cells underwent apoptosis, most underwent senescence over a 10-day period. p53-deficient (E6-transfected U87 and LN-Z308) cells similarly underwent G2-M arrest in response to TMZ, but this arrest was accompanied by only minor changes in p53 or p21(Waf1/Cip1) and was reversed within 7 days of TMZ treatment in association with the appearance of cells with either 8n or subG1 DNA content. These results suggest that glioma cells respond to TMZ by undergoing G2-M arrest. p53 is not necessary for this G2-M arrest to occur but is important in the duration of G2-M arrest and in the ultimate fate of TMZ-treated cells. Therefore, the integrity of the G2-M cell cycle checkpoint may be important in the cytotoxicity of TMZ in glioma cells.
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PMID:p53 effects both the duration of G2/M arrest and the fate of temozolomide-treated human glioblastoma cells. 1128 Jul 52

Temozolomide has an evolving role in the treatment of high grade gliomas. Recent studies suggest that temozolomide is well tolerated and efficacious. This study retrospectively analysed the activity and toxicity associated with temozolomide at two Australian centres over a 24 month period. Fifty-six patients with recurrent high grade gliomas were treated with temozolomide. Patients received temozolomide orally at 150-200mg/m(2)daily, days 1-5, every 4 weeks. The median number of treatment cycles was 4 (1-12). Of the 56 patients, 15 (27%) achieved complete or partial response and 18 (32%) achieved minor response or stable disease. There were no episodes of febrile neutropenia and temozolomide was generally well tolerated. In conclusion, temozolomide is an active therapy in patients with recurrent high grade glioma and our results concord with published studies.
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PMID:An Australian experience with temozolomide for the treatment of recurrent high grade gliomas. 1143 71

Temozolomide (TMZ) produces O(6)-methylguanine in DNA, which in turn mispairs with thymine, triggering futile DNA mismatch repair (MMR) and ultimately cell death. We found previously that in p53-proficient human glioma cells, TMZ-induced futile DNA MMR resulted not in apoptosis but rather in prolonged, p53- and p21-associated G(2)-M arrest and senescence. Additionally, p53-deficient cells were relatively more TMZ resistant than p53-deficient glioma cells, which underwent only transient G(2)-M arrest before death by mitotic catastrophe. These results suggested that prolonged G(2)-M arrest might protect cells from TMZ-induced cytotoxicity. In the present study, we therefore focused on the mechanism by which TMZ induces G(2)-M arrest and on whether inhibition of such G(2)-M arrest might sensitize glioma cells to TMZ-induced toxicity. U87MG glioma cells treated with TMZ underwent G(2)-M arrest associated with Chk1 activation and phosphorylation of both cdc25C and cdc2. These TMZ-induced effects were inhibited by the Chk1 kinase inhibitor UCN-01. Although not in itself toxic, UCN-01 increased the cytotoxicity of TMZ 5-fold, primarily by inhibiting cellular senescence and increasing the percentage of cells bypassing G(2)-M arrest and undergoing mitotic catastrophe. In addition to enhancing TMZ-induced cytotoxicity in p53-proficient cells, UCN-01 also blocked TMZ-induced Chk1 activation and transient G(2)-M arrest in p53-deficient U87MG-E6 cells and similarly enhanced TMZ-induced mitotic catastrophe and cell death. Taken together, these results indicate that Chk1 links TMZ-induced MMR to G(2)-M arrest. Furthermore, inhibition of the cytoprotective G(2) arrest pathway sensitizes cells to TMZ-induced cytotoxicity and may represent a novel, mechanism-based means of increasing TMZ efficacy in both p53 wild-type and p53 mutant glioma cells.
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PMID:Abrogation of the Chk1-mediated G(2) checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells. 1147 24

Despite aggressive treatment, the high-grade malignant glioma (specifically, anaplastic astrocytoma and glioblastoma multiforme) have a poor prognosis with current methods. Relapse is nearly universal, responses in recurrent disease are not enduring, and quality of life because of tumor growth is poor. New treatment strategies that address symptom control and quality of life as well as progression-free and overall survival are urgently needed. Temozolomide (Temodar in the United States, Temodal globally; Schering Corporation, Kenilworth, NJ), a novel, oral, antineoplastic agent, has shown efficacy against high-grade glioma with a favorable safety profile, while maintaining or improving quality of life. In a pivotal randomized, international phase II trial comparing temozolomide (n = 112) with procarbazine (n = 113) in patients with glioblastoma multiforme, temozolomide significantly improved median and 6-month progression-free survival and 6-month overall survival. Additionally, patients receiving temozolomide had superior responses in all seven quality-of-life domains tested, which included the European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire functions and brain-cancer-specific symptoms. A large, multicenter, single-arm trial (N = 162) showed an impressive response rate for patients with relapsed anaplastic astrocytoma receiving temozolomide, and patients maintained or improved their quality of life compared with baseline values. For patients with recurrent malignant glioma, temozolomide provides a therapeutic option with a predictable safety profile, clinical efficacy, and convenient dosing that can provide important quality-of-life benefits.
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PMID:Temozolomide for recurrent high-grade glioma. 1155 Jan 33

Temozolomide is a novel oral alkylating agent that has been approved for the treatment of patients with refractory malignant glioma. Treatment with temozolomide is now being explored in patients with newly diagnosed malignant glioma in several ongoing clinical trials, and alternative treatment schedules are being evaluated. A schedule of continuous daily treatment with temozolomide for 6 or 7 weeks has been developed and determined to be safe, effective, and well tolerated. When temozolomide was continuously given along with a standard course of radiation therapy for 6 or 7 weeks, followed by adjuvant treatment with temozolomide, promising preliminary results were seen in patients with malignant gliomas.
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PMID:New approaches for temozolomide therapy: use in newly diagnosed glioma. 1155 Jan 35


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