The measurement of polyglutamate metabolites of the thymidylate synthase inhibitoR, ICI D1694, in mouse and human cultured cells

Gibson, William A.; Bisset, G. M. F.; Marsham, Peter R.; Kèlland, Lloyd R.; Judson, Ian; Jackman, Ann L.

doi:10.1016/0006-2952(93)90170-2

Cited by 29 publications

(21 citation statements)

References 18 publications

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“…Their measurement in tissue culture cells has been achieved previously after incubation with radiolabelled compounds followed by extraction and HPLC separation (Jolivet et al, 1982;Sikora et al, 1988;Pizzomo et al, 1989;Jackman et al, 1991c;Gibson et al, 1993). Similar methodology has been used to measure the polyglutamated forms of methotrexate in isolated human leukaemic blast cells (Goker et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…The polyglutamated forms of ZD1694 are more effective inhibitors of TS than the parent compound (e.g. the Kj for mouse enzyme of the tetraglutamate metabolite is 1 nM) and are also retained within cells (Jackman et al, 1991a;Gibson et al, 1993). The prolonged inhibition of TS in intact cells (Jackman et al, 1995b;Aheme et al, 1996a), even after removal of drug from the medium, is consistent with the formation and retention of active intracellular polyglutamated species.…”

mentioning

confidence: 84%

“…L1210 mouse leukaemia cells (2-3 x 106) and an acquired resistant variant of the cell line (LI21OR:D1694; 6-8x106 cells), which has an impaired ability to polyglutamate ZD1694 (Jackman et al, 1995c), were exposed to ZD1694 (0.1 gM and 1 gM) for 4 or 24 h and, after harvesting and washing as described previously (Gibson et al, 1993;Jackman et al, 1995c), were resuspended in 0.5 ml of harvested 24 h and 72 h after dosing. One dog was treated with saline and used to provide control samples.…”

Section: Intracellular Drug Levelsmentioning

confidence: 99%

“…Polyglutamated forms of the quinazoline antifolates have previously been measured in vitro using radiolabelled drugs. Separation of polyglutamated metabolites by HPLC was followed by quantitation in fractions using radiochemical analysis (Jackman et al, 1991c;Gibson et al, 1993) or by measuring inhibition of TS (Sikora et al, 1988). In preliminary experiments, direct evidence of polyglutamation in tissues has been obtained by administration of radiolabelled drug to mice (Jackman et al, 1995a).…”

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confidence: 99%

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Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models

Aherne

Ward²,

Lawrence³

et al. 1998

Br J Cancer

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Summary ZD1 694 (Tomudex, raltitrexed) is a specific quinazoline antifolate thymidylate synthase inhibitor that relies on polyglutamation for high potency. Antibodies to ZD1694 have been used to establish a sensitive radioimmunoassay as an alternative to high-performance liquid chromatography (HPLC). The radioimmunoassay is reproducible, accurate and provides a means of determining low levels of ZD1694 in plasma (< 1 nM). By virtue of the high cross-reactivity of the antibodies with polyglutamated forms of ZD1 694, it is also possible to measure the total concentration of drug in tissues. Results obtained in L1210 mouse leukaemia cells and in mouse tissues were similar to those previously determined using radiolabelled drug. Pharmacokinetic studies in mice have confirmed that the compound is rapidly eliminated from the plasma and that there is a prolonged terminal elimination phase. ZD1694 was measured in plasma (0.56 ng ml-1; 1.2 pmol ml-') up to 7 days after a single i.p. dose of 100 mg kg-' ZD1 694. Liver, kidney and gut epithelium had a substantially higher level of ZD1 694 immunoreactivity than plasma. For example, 24 h after a single i.p. dose at 1, 10 and 100 mg kg-', total drug levels in the liver were 480, 325 and 152 times higher than plasma levels respectively. In kidney and gut epithelium, total drug levels at these doses were approximately 55 and 34 times those of plasma. The high tissue to plasma ratios were maintained for at least 7 days after administration. Similarly, high tissue to plasma ratios (> 100) were found in dogs treated with a clinically relevant dose of ZD1 694. These were maintained for 4 weeks in liver and kidney tissue (> 100). Total gastrointestinal concentrations of ZD1694 were approximately 10 times higher than plasma 3 days after administration, but levels were near to the limit of detection at 4 weeks. These results are consistent with extensive polyglutamation of ZD1 694 within tissues in both mice and dog and provide further support for the infrequent schedule that has been used clinically. Although it has not been possible to measure individual polyglutamated forms of ZD1 694, the radioimmunoassay provides a convenient means of assessing total drug levels in tissues and is currently the only method suitable for measuring the extent of drug retention in normal tissue and tumour biopsies obtained from patients treated with ZD1 694.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 84%

Section: Intracellular Drug Levelsmentioning

confidence: 99%

mentioning

confidence: 99%

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Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models

Aherne

Ward²,

Lawrence³

et al. 1998

Br J Cancer

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“…Many of these new compounds showed improved substrate activity for the reduced folate/methotrexate cell membrane transport carrier protein (RFC) and folylpolyglutamate synthetase (FPGS), rendering them potent as cytotoxic agents (Jackman et al, 1991d). Polyglutamates of ZD1694 rapidly accumulate within the cell and studies have confirmed these to be the cytotoxic species (Jackman et al, 1991a, 1993a, Ward et al, 1992Gibson et al, 1993). For example, a major metabolite, the tetraglutamate, is a 60-fold better TS inhibitor (K = 1 nM) than the parent drug and is not readily effluxed from cells.…”

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confidence: 99%

Mechanisms of acquired resistance to the quinazoline thymidylate synthase inhibitor ZD1694 (Tomudex) in one mouse and three human cell lines

Kèlland²,

Kimbell³

et al. 1995

Br J Cancer

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A Phase I study of raltitrexed and paclitaxel given every 3 weeks to patients with solid tumors

Vokes

Goh

Bertucci

et al. 1999

Cancer

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BACKGROUND Raltitrexed is a novel thymidylate synthase inhibitor with single agent activity in colorectal, nonsmall cell lung, and breast carcinomas. The recommended Phase II dose of raltitrexed administered as a single agent is 3 mg/m2 every 3 weeks. Paclitaxel also has a broad spectrum of activity. A Phase I study of both agents in combination therapy was conducted. METHODS Eligible patients had refractory solid tumors and a Cancer and Leukemia Group B performance status of 0 to 2. Cohorts of patients were treated with escalating doses of raltitrexed as a 15‐minute intravenous infusion immediately followed by 175 mg/m2 of paclitaxel administered over 3 hours. Dose‐limiting toxicity was defined as World Health Organization Grade 4 neutropenia with fever, Grade 4 thrombocytopenia requiring platelet transfusion, a nonhematologic toxicity of Grade 3 or higher (excluding nausea, emesis, and alopecia), or failure of toxicities to recover to Grade 1 or lower within 21 days after causing a dose delay. RESULTS A total of 33 patients enrolled in the study. Raltitrexed was escalated in increments of 0.5 mg/m2, from 0.5 mg/m2 to the recommended Phase II dose of 3 mg/m2. Dose‐limiting toxicity first was observed at a raltitrexed dose of 2 mg/m2. At a dose of 3 mg/m2, dose‐limiting neutropenia was observed in 2 of 12 patients. Diarrhea was the other dose‐limiting toxicity. Two patients achieved a partial response (one patient with carcinoma of the head and neck and another with gallbladder carcinoma). CONCLUSIONS The authors conclude that raltitrexed and paclitaxel may be administered in combination at their respective single agent Phase II doses. Phase II testing of this combination is indicated. Cancer 1999;86:528–32. © 1999 American Cancer Society.

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The measurement of polyglutamate metabolites of the thymidylate synthase inhibitoR, ICI D1694, in mouse and human cultured cells

Cited by 29 publications

References 18 publications

Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models

Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models

Mechanisms of acquired resistance to the quinazoline thymidylate synthase inhibitor ZD1694 (Tomudex) in one mouse and three human cell lines

A Phase I study of raltitrexed and paclitaxel given every 3 weeks to patients with solid tumors

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