UMLS:C0017638 - FACTA Search

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)

We have previously demonstrated (A. E. Pegg, Cancer Res., 50: 6119-6129, 1990) that O6-benzylguanine (O6-BG) enhances nitrosourea, temozolomide, and cyclophosphamide activity in malignant glioma xenografts growing in athymic nude mice. More recently, we have demonstrated (V. J. Patel et al., Clin. Cancer Res., 6: 4154-4157, 2000; P. Pourquier et al., Cancer Res., 61: 53-58, 2001) that the combination of temozolomide plus irinotecan (CPT-11) displays a schedule-dependent enhancement of antitumor activity secondary to trapping of topoisomerase I by O6-methylguanine residues in DNA. These studies suggested that there might be favorable therapeutic interactions between O6-BG and combinations of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) plus cyclophosphamide or temozolomide plus CPT-11, respectively. Our present results indicate that the combination of cyclophosphamide plus BCNU plus O6-BG produces growth delays modestly-to-markedly-superior to combinations of cyclophosphamide with BCNU. Although the combination of temozolomide and CPT-11 reveals a marked increase in activity compared with either agent used alone, the addition of O6-BG to this combination dramatically increased the growth delay of the O6-alkylguanine-DNA alkyltransferase (AGT)-positive malignant glioma D-456 MG. These results suggest that a Phase I trial of CPT-11 plus temozolomide plus O6-BG in AGT-positive tumors may be an important intervention to maximize the therapeutic benefits of the combination of CPT-11 and temozolomide.
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PMID:O6-benzylguanine-mediated enhancement of chemotherapy. 1248 16

Irinotecan is a water-soluble derivative of camptothecin, an alkylator originally extracted from the Chinese tree Camptotheca acuminata. Laboratory studies have demonstrated the activity of irinotecan in a broad panel of pediatric and adult central nervous system tumor xenografts in athymic nude mice. These studies led to a Phase II trial that confirmed the activity of this agent in the treatment of recurrent malignant glioma. Subsequent laboratory studies have demonstrated that a combination of irinotecan (CPT-11) and alkylating agents, particularly 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), increases antitumor effects to a level well above the additive effects of the individual agents. These laboratory studies generated a recently completed Phase I trial of CPT-11 + BCNU, which now is being evaluated in a formal Phase II trial for adults with newly diagnosed or recurrent malignant glioma. More recent studies have demonstrated similar interaction between CPT-11 and temozolomide and have led to a Phase I trial of these agents in the treatment of adults with malignant glioma. Studies currently are addressing the role of O(6)-alkylguanine-DNA alkyltransferase (AGT) in reducing the benefits of combining CPT-11 with temozolomide and the potential therapeutic gain from utilizing an inhibitor of AGT.
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PMID:The emerging role of irinotecan (CPT-11) in the treatment of malignant glioma in brain tumors. 1271 57

The topoisomerase-I inhibitor irinotecan (CPT-11) is currently used in Phase I/II trials for the treatment of patients with recurrent malignant gliomas. Protein kinase C (PKC) inhibitors such as high-dose tamoxifen and hypericin also have been used in the treatment of malignant gliomas. The current study examined the role of PKC inhibitors as chemosensitizers for CPT-11 and their proposed mechanism of action. Two glioma cell lines (A-172 and U-87) and one primary glioma cell culture (LA-567) were used. Proliferation ((3)H-thymidine) and cytotoxicity (methylthiotetrazole) studies were performed using CPT-11 (0-100 microM) alone, 7-ethyl-10-hydroxy camptothecin (SN-38) (0-1000 nM) alone or in the presence of a PKC inhibitor, tamoxifen (10 microM), hypericin (10 microM), calphositin C (400 nM), or staurosporine (10 nM). The terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL) assay was used to determine apoptosis as the mechanism of cytotoxicity; alterations in bcl-2 and bax expression were determined using Western blot analysis. Conversion of CPT-11 to SN-38 by glioma cells was determined using high-performance liquid chromatography (HPLC) analysis. Increasing CPT-11 and SN-38 concentrations induced cytotoxic morphologic changes, decreased proliferation, and increased cytotoxicity on all glioma cell lines tested. These changes were increased in the presence of a PKC inhibitor. The mechanism of the cytotoxicity was determined to be apoptosis by the TUNEL assay. The combination of a PKC inhibitor with CPT-11 or SN-38 led to decreased expression of the antiapoptotic protein bcl-2, and increased expression of the proapoptotic protein bax. HPLC analysis demonstrated conversion of CPT-11 to SN-38 by glioma cells. A combination of CPT-11 or SN-38 with a PKC inhibitor was found to lead to a decrease in proliferation and an increase in apoptosis in malignant glioma cells. The induction of apoptosis was secondary to a decrease in bcl-2 and an increase in bax expression. Glioma cells are capable of converting CPT-11 to SN-38 by intrinsic tumor carboxylesterases.
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PMID:Combination therapy with irinotecan and protein kinase C inhibitors in malignant glioma. 1271 58

Two studies were performed to evaluate the safety, tolerability, and efficacy of irinotecan (CPT-11) in the treatment of adults with malignant glioma. Patients with progressive or recurrent malignant gliomas were enrolled. In the first study, CPT-11 was administered once every 3 weeks as a 90-minute intravenous infusion at a dose of 300 mg/m(2). After 2 treatments, doses were increased to 350 mg/m(2) in those patients without Grade 3/4 toxicities. Dose modifications were made for toxicities. All 14 patients who enrolled (11 males and 3 females) were treated with CPT-11 and were assessable for survival, response, and toxicity. The majority of patients (86%) had prior surgery. Two patients had a confirmed partial response (PR), and 2 patients (14%) had stable disease (SD). Median survival was 24 weeks; median time to tumor progression (TTP) was 6 weeks. The primary hematologic toxicity was Grade 3/4 neutropenia, which was observed in 14% of patients. Infrequent Grade 3/4 nonhematologic toxicity was observed, possibly due to the concomitant use of anticonvulsants that might have altered pharmacokinetics. The second study evaluated the potential underdosing observed in patients who did or did not receive enzyme-inducing antiepileptic drugs (EIAED) by implementing an intrapatient dose escalation design. In this open-label study, treatment of patients with recurrent malignant glioma (rMG) was started at 300-400 mg/m(2) of CPT-11 every 3 weeks and, depending on individual safety and efficacy evaluation, escalated by steps of 100 mg/m(2) in subsequent courses. Thirty-five patients (median age, 43 years; gender, 11F and 24M; histology, 26 glioblastoma multiforme and 9 anaplastic glioma) have completed at least two cycles of chemotherapy and are evaluable for toxicity and response. Dose-limiting toxicity (DLT) was reached in 12 patients at doses ranging from 400-1700 mg/m(2). Preliminary efficacy data show that 3 patients exhibited PR and 15 patients exhibited SD. Median TTP was 2.7 months, and median survival was 8.5 months. Patients who did not receive anticonvulsants achieved higher peak concentrations, relative to dose, of the active metabolite SN-38 than did patients in the EIAED group. This study confirmed the activity of CPT-11 in malignant glioma and indicated that the maximum tolerated dose (MTD) for patients with rMG was considerably higher than expected but still possessed significant variability. A higher level of efficacy for CPT-11 may be observed if an MTD can efficiently be established for each patient.
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PMID:Two studies evaluating irinotecan treatment for recurrent malignant glioma using an every-3-week regimen. 1271 60

Patients with malignant glioma continue to have a dismal outcome. Those with glioblastoma multiforme, the most common type of malignant glioma, have a median survival of 40 to 60 weeks following diagnosis and only 16 to 24 weeks after recurrence. While standard therapy is surgery and external-beam radiotherapy, data indicate that chemotherapy improves the clinical outcome of some patients. Irinotecan (CPT-11, Camptosar) possesses significant activity against malignant glioma, and potentiation of this activity with combination partners, including the alkylator 1,2-bis(2-chloroethyl)-1-nitrosourea (carmustine, BCNU), is being evaluated in an ongoing phase II study. Also, the combination of irinotecan plus temozolomide (Temodar) has produced synergism in preclinical studies as well as encouraging responses in ongoing clinical trials. Other investigative directions include studies of irinotecan plus temozolomide and O6-benzylguanine (O6-BG) to assess the ability of O6-BG to maximize the therapeutic benefits of irinotecan combined with temozolomide.
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PMID:Irinotecan: promising activity in the treatment of malignant glioma. 1280 Jun

7-Ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (irinotecan, CPT-11) is a camptothecin prodrug that is metabolized by carboxylesterases (CE) to the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), a topoisomerase I inhibitor. CPT-11 has shown encouraging antitumor activity against a broad spectrum of tumor types in early clinical trials, but hematopoietic and gastrointestinal toxicity limit its administration. To increase the therapeutic index of CPT-11 and to develop other prodrug analogues for enzyme/prodrug gene therapy applications, our laboratories propose to develop camptothecin prodrugs that will be activated by specific CEs. Specific analogues might then be predicted to be activated, for example, predominantly by human liver CE(hCE1), by human intestinal CE (hiCE), or in gene therapy approaches using a rabbit liver CE (rCE). This study describes a molecular modeling approach to relate the structure of rCE-activated camptothecin prodrugs with their biological activation. Comparative molecular field analysis, comparative molecular similarity index analysis, and docking studies were used to predict the biological activity of a 4-benzylpiperazine derivative of CPT-11 [7-ethyl-10-[4-(1-benzyl)-1-piperazino]carbonyloxycamptothecin (BP-CPT)] in U373MG glioma cell lines transfected with plasmids encoding rCE or hiCE. BP-CPT has been reported to be activated more efficiently than CPT-11 by a rat serum esterase activity; however, three-dimensional quantitative structure-activity relationship studies predicted that rCE would activate BP-CPT less efficiently than CPT-11. This was confirmed by both growth inhibition experiments and kinetic studies. The method is being used to design camptothecin prodrugs predicted to be activated by specific CEs.
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PMID:Activation of a camptothecin prodrug by specific carboxylesterases as predicted by quantitative structure-activity relationship and molecular docking studies. 1461 91

This study was conducted to determine the maximum tolerated dose and dose-limiting toxicity of irinotecan (CPT-11) administered every 3 weeks to adults with progressive malignant glioma who were treated with enzyme inducing antiepileptic drug (EIAED) therapy, and to compare the pharmacokinetics with those in patients not on EIAED therapy treated at the recommended phase 2 dose for other cancers. The CPT-11 dose was 350 mg/m(2) i.v. every 3 weeks and remained fixed in patients not on EIAED therapy, but the dose was escalated by 50-mg/m(2) increments in patients on EIAED therapy. CPT-11 and its metabolites SN-38, SN-38 glucuronide (SN-38G), and APC (7-ethyl-10[4-N-(5 aminopentanoic acid)-1-piperidine]-carbonyloxycamptothecin) were characterized in both groups. Patients on EIAEDs received 350 to 800 mg/m(2) of CPT-11. Dose-limiting toxicity was due to grade 3 diarrhea despite maximal doses of loperamide. The systemic levels of CPT-11, APC, SN-38G, and SN-38 were all lower in the EIAED group. There was a moderate-to-fair relationship between CPT-11 dose and the area under the curve (AUC) for CPT-11 and APC over the 2, but no relationship dosage range of 350 to 800 mg/m between CPT-11 dose and the AUC for SN-38 or SN-38G. At the 750-mg/m(2) dose, the AUC for CPT-11 (21.6 microg x h/ml) matched the AUC (21.6 microg x h/ml) in the non-EIAED group treated with 350 mg/m(2) of CPT-11. We conclude that the recommended phase 2 dose of CPT-11 for patients on EIAEDs is 750 mg/m(2) when given every 3 weeks. A phase 2 study of patients with recurrent malignant glioma is ongoing to assess the efficacy of CPT-11 when the dose is stratified according to the use of EIAEDs.
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PMID:Phase 1 trial of irinotecan (CPT-11) in patients with recurrent malignant glioma: a North American Brain Tumor Consortium study. 1476 40

This adjunct to a prospective phase II blinded study of 48 patients with recurrent malignant glioma evaluated the predictive reliability of an extreme drug resistance (EDR) to identify clinical resistance to irinotecan (CPT-11), using fresh tumor biopsies obtained from recurrent patients immediately prior to their first dose of CPT-11 therapy. In vitro tumor response to SN38 (bioactive species of CPT-11 used in the EDR assay) determined prior to treatment was correlated with objective response, time to tumor progression (TTP) and survival following the administration of CPT-11. SN38 activity was tested in 19 of 29 tumors, with 15 of 18 assay results evaluable for correlation with clinical outcomes. In vitro drug resistance was classified as either extreme, intermediate (IDR), or low (LDR). TTP and survival were estimated by the Kaplan-Meier method, and compared using the Mantel-Haenszel log-rank and Fisher's exact test statistics. In vitro tumor response was bifurcated into either EDR (n = 4) or IDR/LDR (n = 11) categories for comparison with outcomes. Results correlated significantly with both TTP and survival. Median TTP for IDR/LDR cases was 3 months versus 6 weeks for EDR cases (log-rank test; p = 0.0288, hazards ratio = 3.06). A 13-week median survival for EDR cases was significantly shorter compared to 38 weeks for IDR/LDR cases (p = 0.029). Further, 100-day survival favored the IDR/LDR cases (Fisher's exact test; p = 0.008). At last follow-up, two of three survivors were patients who had tumors IDR/LDR to SN38. These prospective data support the notion that patients should avoid agents to which their tumor demonstrates EDR.
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PMID:A prospective blinded study of the predictive value of an extreme drug resistance assay in patients receiving CPT-11 for recurrent glioma. 1501 70

In preclinical studies, BCNU, or 1,3-bis(2-chloroethyl)-1-nitrosourea, plus CPT-11 (irinotecan) exhibits schedule-dependent, synergistic activity against malignant glioma (MG). We previously established the maximum tolerated dose of CPT-11 when administered for 4 consecutive weeks in combination with BCNU administered on the first day of each 6-week cycle. We now report a phase 2 trial of BCNU plus CPT-11 for patients with MG. In the current study, BCNU (100 mg/m2) was administered on day 1 of each 6-week cycle. CPT-11 was administered on days 1, 8, 15, and 22 at 225 mg/m2 for patients receiving CYP3A1- or CYP3A4-inducing anticonvulsants and at 125 mg/m2 for those not on these medications. Newly diagnosed patients received up to 3 cycles before radiotherapy, while recurrent patients received up to 8 cycles. The primary end point of this study was radiographic response, while time to progression and overall survival were also assessed. Seventy-six patients were treated, including 37 with newly diagnosed tumors and 39 with recurrent disease. Fifty-six had glioblastoma multiforme, 18 had anaplastic astrocytoma, and 2 had anaplastic oligodendroglioma. Toxicities (grade > or =3) included infections (13%), thromboses (12%), diarrhea (10%), and neutropenia (7%). Interstitial pneumonitis developed in 4 patients. Five newly diagnosed patients (14%; 95% CI, 5%-29%) achieved a radiographic response (1 complete response and 4 partial responses). Five patients with recurrent MG also achieved a response (1 complete response and 4 partial responses; 13%; 95% CI, 4%-27%). More than 40% of both newly diagnosed and recurrent patients achieved stable disease. Median time to progression was 11.3 weeks for recurrent glioblastoma multiforme patients and 16.9 weeks for recurrent anaplastic astrocytoma/ anaplastic oligodendroglioma patients. We conclude that the activity of BCNU plus CPT-11 for patients with MG appears comparable to that of CPT-11 alone and may be more toxic.
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PMID:Phase 2 trial of BCNU plus irinotecan in adults with malignant glioma. 1513 28

Carboxylesterases, expressed at high levels in human liver and intestine, are thought to detoxify xenobiotics. The anticancer prodrug 7-ethyl-10-[4-1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) is also metabolized by carboxylesterases to produce the active drug 7-ethyl-10-hydroxycamptothecin. Activation of CPT-11 by human intestinal carboxylesterase (hiCE) in the human intestine may contribute to delayed onset diarrhea, a dose-limiting side effect of this drug. The goal of this study was to develop small molecule inhibitors selective for hiCE to circumvent or treat the toxic side effects of CPT-11. A secondary goal was to develop molecules that specifically inhibit activation of CPT-11 by a rabbit liver carboxylesterase (rCE). rCE is the most efficient CPT-11-activating enzyme thus far identified, and this enzyme is being developed for viral-directed enzyme prodrug therapy applications. Based on in vitro assays with partially purified hiCE and rCE proteins and on growth inhibition assays using U373MG human glioma cells transfected to express hiCE or rCE (U373pIREShiCE or U373pIRESrCE), we identified specific inhibitors of each enzyme. Lead compounds are derivatives of nitrophenol having 4-(furan-2-carbonyl)-piperazine-1-carboxylic acid or 4-[(4-chlorophenyl)-phenylmethyl]-piperazine-1-carboxylic acid substitutions in the p position. Kinetic analysis of each compound for hiCE compared with rCE showed that the Ki values of the most selective of these inhibitors differed by 6- to 10-fold. In growth inhibition assays, nontoxic, low micromolar concentrations of these inhibitors increased the EC50 of CPT-11 for U373pIREShiCE or U373pIRESrCE cells by 13- to >1,500-fold. The four compounds characterized in this study will serve as lead compounds for a series of inhibitors to be constructed using a combinatorial approach.
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PMID:Characterization of inhibitors of specific carboxylesterases: development of carboxylesterase inhibitors for translational application. 1529 73

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