Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027627 (metastases)
 103,950 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Approximately 50% of patients with colorectal cancer develop locally recurrent or distant metastatic disease during the course of their illness and eventually die. Since the 1950s the mainstay of treatment for patients in need of palliative therapy has been and continues to be the fluoropyrimidines. When 5-fluorouracil (5-FU) was first introduced into the clinic it was used as a single agent given by rapid intravenous injection. Results with this drug have been disappointing, with response rates consistently low, usually of brief duration, and with little or no impact on survival. During the 1970s and 1980s, multidrug regimens were evaluated with little or no improvement in outcome. More recently, our understanding of the metabolism, pharmacology, and the mechanisms of action as well as the potential mechanisms of resistance to 5-FU has led to its more rational use. This knowledge has resulted in the design of treatment programs with improved therapeutic effects by changing its route of administration, combining it with biochemical modulators and using it in conjunction with other chemotherapeutic agents. These strategies have created new optimism for improved results with less toxicity. More potent inhibitors of thymidylate synthase (TS) such as tomudex and trimetrexate have been developed and are currently being evaluated in the clinic either alone or in combination with 5-FU. Semisynthetic topoisomerase inhibitors such as irinotecan have shown encouraging results as first-line therapy, in combination with 5-FU or as salvage therapy.
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PMID:Chemotherapy for the treatment of patients with metastatic colorectal cancer: an overview. 927 7

The introduction of oxaliplatin into the colorectal cancer setting represents a significant advancement in the treatment of the disease. Synergistic effects with traditional therapy 5-fluorouracil/folinic acid have increased response rates significantly, improved time-sensitive response parameters, and facilitated the removal of previously unresectable hepatic metastases, thus changing the natural history of the disease. Ongoing and planned trials are identifying various issues that need to be addressed to fully realize the potential of oxaliplatin. These include optimization of dosing and schedule of administration, determination of the most effective oxaliplatin-5-fluorouracil/folinic acid combination, definition of the role of new thymidylate synthase inhibitors with respect to oxaliplatin therapy, and identification of the most effective combinations of oxaliplatin with the new anticancer agents that have been recently introduced. Providing the answers to these questions will contribute to changing the attitude of the clinical oncologist regarding what strategy to adopt in treating colorectal cancer in the coming years.
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PMID:Oxaliplatin for the treatment of advanced colorectal cancer: future directions. 960 8

1. Painstaking progress in drug development is well illustrated by 5-fluorouracil (5FU), originally designed 40 years ago as a fluorinated analogue of the naturally occurring base uracil. Innovative pharmacokinetic and pharmacodynamic strategies have seen significant clinical improvements for cancer patients over the past decade. 2. 5-Fluorouracil acts by three main mechanisms. Principally, the intermediate metabolite fluorodeoxyuridine monophosphate inhibits a key enzyme in pyrimidine biosynthesis, namely thymidylate synthase (TS). Additionally, 5FU is metabolized to ribo- and deoxy-ribonucleotides, which act as false bases for incorporation into RNA and DNA. 3. Biomodulation of 5FU has been attempted with methotrexate (MTX), folinic acid, interferons, cisplatin and radiotherapy. Methotrexate augments the actions of 5FU by inhibiting dihydrofolate reductase and decreasing the folate pool required for pyrimidine biosynthesis, inhibiting TS via MTX-polyglutamate and directly inhibiting purine biosynthesis. Interferons increase steady state concentrations of 5FU. 5-Fluorouracil enhances the cytotoxicity of cisplatin and radiotherapy by inhibiting DNA repair. Folinic acid enhances TS inhibition by increasing the intracellular pool of folates that stabilize the 5FU-TS complex. 4. 5-Fluorouracil has a short plasma half-life. Thymidylate synthase inhibition is limited to the S-phase of the cell cycle and only a small fraction of most cancer cells are in S-phase at any one time. Increased response rates seen with infusional protocols may reflect the effective recruitment of additional mechanisms of cytotoxicity, not dependent on cell cycle, including effects on RNA synthesis. 5. Patients with localized metastatic disease may benefit from locoregional treatments. These include hepatic intra-arterial therapy with related compounds, such as floxuridine, which reach high concentrations at sites of tumour, while systemic toxicities are minimized by efficient hepatic clearance. 6. Recent developments include orally bioavailable formulations, such as ftorafur, capecitabine and the combination of 5FU with the dihydropyrimidine phosphate dehydrogenase inhibitor ethynyluracil. Recognition of diurnal variation in the activity of such key enzymes as DPD has led to the administration of 5FU at regulated, variable infusion rates (chronomodulation). These promising pharmacological approaches may further improve clinical outcomes in common cancers.
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PMID:5-fluorouracil: a pharmacological paradigm in the use of cytotoxics. 980 59

The current phase III studies of chemotherapy in advanced colorectal cancer include 60% to 85% of patients with the liver as a site of metastatic disease. Within the past 10 years, various modulatory combinations of 5-fluorouracil (5-FU) with agents such as leucovorin, interferon, N-(phosphonacetyl)-L-aspartate (PALA), and methotrexate have produced higher response rates than 5-FU alone. A major seven-arm study, conducted by the Southwestern Oncology Group and reported in 1995, suggested that single-agent, continuous-infusion 5-FU demonstrated the most encouraging results. Nine of 12 reported randomized studies comparing the combination of 5-FU and leucovorin with 5-FU alone report significant increases in response rates; two studies reported significant increases in survival. The meta-analysis project involving 1381 patients confirmed the increase in response rate with the combination (23%) vs. 5-FU alone (11%) but did not demonstrate any significant difference in median survival. The current issues involving 5-FU administration largely concentrate on the best approach (modulation vs. scheduling) and comprehensive evaluation of end points (quality of life, survival, and pharmacoeconomics). The current literature examining quality-of-life issues suggests that 5-FU and low-dose leucovorin produce the best overall improvement in symptoms. Others argue that continuous-infusion scheduling is also associated with a very good quality of life (although the increased cost and morbidity of continuous-infusion administration has to be factored into this consideration). An important phase III study is currently being conducted by the National Cancer Institute of Canada comparing immediate vs. delayed (until symptomatic) chemotherapy in patients with advanced colorectal cancer. Of the new approaches to therapy, perhaps the most immediately applicable are the new thymidylate synthase inhibitors (in particular, Tomudex, which produces a response rate equivalent to that of 5-FU plus leucovorin with less toxicity and a more convenient schedule).
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PMID:Management of hepatic metastases from colorectal cancer: systemic chemotherapy. 983 94

Phase III studies have shown irinotecan prolongs survival significantly when compared with either best supportive care or best infusional 5-fluorouracil (5-FU)-based chemotherapy in patients with 5-FU-resistant colorectal cancer. Phase I/II studies are investigating the combination of irinotecan with 5-FU, with thymidylate synthase inhibitors, notably raltitrexed, and with the oral fluoropyrimidines. Preliminary results suggest irinotecan and raltitrexed can safely be combined in the clinic and that this combination is active. The combination of irinotecan with the oral fluoropyrimidines also has produced promising results. A phase I study of irinotecan plus 5-FU/folinic acid showed high activity in first-line metastatic disease and further trials using the doses of 80 mg/m2 irinotecan plus 2 g 5-FU weekly are recommended. The combination of irinotecan with the De Gramont 5-FU regimen is feasible and active in patients with 5-FU-resistant metastatic disease. Alternating exposure to irinotecan and 5-FU may be as active as either treatment alone, and has been associated with overall response rates (ORRs) greater than 30% and encouraging median survival. The combination of irinotecan with oxaliplatin is also feasible and levels of response rates are in the region of 50% (especially with a 2-weekly administration schedule). In patients with advanced gastric cancer (including those with pretreated disease) ORRs of around 50% have been reported following administration of either cisplatin plus irinotecan or cisplatin plus docetaxel.
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PMID:Clinical advances with topoisomerase I inhibitors in gastrointestinal malignancies. 1063 Mar 62

Several studies have suggested that the intratumoral level of thymidylate synthase (TS) in colorectal tumors correlates with survival. We have studied the correlation between TS expression in primary rectal cancer and locoregional recurrence, distant metastases, and survival. TS enzyme levels were evaluated immunohistochemically using the specific monoclonal antibody TS 106 in paraffin-embedded tumors from 243 patients who had undergone primary surgery for rectal cancer during the years 1980-1993. All patients were included in prospective randomized trials aimed at determining the clinical value of a short preoperative course of local radiation therapy (five doses of 5 Gy each). With a median follow-up of 94 months (range, 43-202 months), it was observed by multivariate analysis that Dukes' stage and TS expression were independent prognostic markers of locoregional recurrence (P < 0.001 and P = 0.038, respectively) distant metastasis (P < 0.001 and P = 0.011, respectively) disease-free survival (P < 0.001 and 0.014, respectively), and overall survival (P < 0.001 and 0.020, respectively). By multivariate analysis, preoperative irradiation therapy showed a borderline improvement in locoregional recurrence (P = 0.051). No other factors, such as age, sex, differentiation of the tumor, or p53 expression, were noted to be independent prognostic factors for clinical outcome in these patients. We concluded that the intratumoral expression of TS in primary rectal cancer is an independent prognostic factor for locoregional recurrence, distant metastases, disease-free survival, and overall survival. Patients with low intratumoral TS expression had a significantly better outcome than those with high TS expression.
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PMID:Thymidylate synthase expression: an independent prognostic factor for local recurrence, distant metastasis, disease-free and overall survival in rectal cancer. 1077 66

We recently reported that forced overexpression of the transcription factor E2F-1 in human HT-1080 fibrosarcoma cells resulted in corresponding high levels of thymidylate synthase (TS) and resistance to 5-fluoropyrimidines (D. Banerjee et al., Cancer Res., 58: 4292-4296, 1998). Because colorectal metastasis to the lung has higher TS levels than liver metastasis and is less responsive to treatment with 5-fluorouracil (R. Gorlick et al., J. Clin. Oncol., 16: 1465-1469, 1998), it was, therefore, of interest to measure E2F-1 expression in these tumors. In contrast to marginally increased levels of dihydrofolate reductase and topoisomerase I in lung metastasis as compared with liver metastasis, lung tumors had a 5-fold increase in E2F-1 expression as compared with liver tumors, corresponding to the relative levels of TS in these metastases. These data indicate that there exists a close correlation between E2F-1 and TS levels and provide a rationale for targeting this transcription factor, ie., E2F-1, for the treatment of certain cancers.
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PMID:Levels of E2F-1 expression are higher in lung metastasis of colon cancer as compared with hepatic metastasis and correlate with levels of thymidylate synthase. 1081 Nov 10

S-phase fraction (SPF) is a reference for cell-kinetic analysis. In this study, the links between SPF and the essential enzymes participating in the pyrimidine synthesis were investigated in breast cancer and their relationships with the natural history of the disease were compared. We measured thymidine kinase (TK) for salvage synthesis, thymidylate synthase (TS) for de novo synthesis and thymidylate kinase (TMK), which is required for both pathways. Our study population consisted of 211 premenopausal women with node-negative tumors. SPF was assessed prospectively by flow cytometry, whereas enzyme activities were measured retrospectively in cytosols using radioenzymatic methods. Among the enzymes analyzed, only TK demonstrated a strong correlation with SPF (r(s) = 0.59). In univariate analysis, high SPF and high levels of TK were associated with increased risk of developing distant recurrences (p < 0.001). Correlations with other prognostic factors (histological grade, steroid receptors, DNA ploidy status, urokinase plasminogen activator and plasminogen activator inhibitor type 1) confirmed a parallel association of SPF and TK with the most aggressive tumors. In contrast, TS and TMK were not associated with prognosis. After adjustment for SPF, the risk of relapse increased significantly with TK values. Subgroup analysis showed that additional information was provided by TK in the tumors with low SPF. When urokinase plasminogen activator (uPA) was a candidate variable in multivariate analysis, TK remained significant. Combined with SPF and uPA, TK could be useful to define premenopausal node-negative patients with rapidly proliferating tumors at a high risk of metastatic disease.
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PMID:DNA-synthesizing enzymes in breast cancer (thymidine kinase, thymidylate synthase and thymidylate kinase): association with flow cytometric S-phase fraction and relative prognostic importance in node-negative premenopausal patients. 1124 12

In colorectal cancer, leucovorin-modulated 5-fluorouracil (5-FU) has been the mainstay of both adjuvant treatment and treatment of metastatic disease for many years. In advanced disease, response rates of 10-43% are reported; efforts to improve efficacy through schedule modification, including prolonged infusions, have led to limited success. New agents with improved efficacy, tolerability and ease of administration are required. Among the newer drugs, irinotecan and oxaliplatin are becoming established as first- and second-line treatment for advanced disease. Their novel mechanisms of action have proven to be of value in 5-FU-resistant patients. In tandem with these developments, thymidylate synthase inhibition has remained an important objective and oral fluoropyrimidines such as capecitabine and UFT (uracil plus tegafur)/leucovorin have been developed with this goal in mind. Two large, phase III studies of capecitabine in metastatic disease demonstrated objective response rates of 26.6 and 24.8%. UFT/leucovorin has also been evaluated in phase III trials, with an 11.7% response rate reported. Both agents are being evaluated in combination with oxaliplatin and irinotecan, and ultimately oral fluoropyrimidines as monotherapy or combination therapy may replace intravenous (i.v.) 5-FU as first-line treatment for metastatic colorectal cancer.
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PMID:Integrating the oral fluoropyrimidines into the management of advanced colorectal cancer. 1131 69

The enzyme thymidylate synthase (TS) is an important target of 5-fluorouracil (FUra) that is utilized for the treatment of disseminated colorectal cancer. One determinant of clinical response to FUra-based therapy is TS expression. with high levels of expression being predictive of poor response. In the present investigation the levels of immunoreactive TS were analyzed in human colon metastases in the liver (n=l1). The levels of TS ranged from 0.30 to 4.60 pmol TS/g tissue. A good correlation was observed between the levels of immunoreactive TS and TS mRNA (n=6, r=0.69). Of the 11 metastases analyzed, 5 exhibited relatively high levels of TS expression. Two metastases with high TS expression were obtained from patients who received adjuvant therapy with FUra. In 4 metastases with relatively high levels of TS expression, TS gene copy number was analyzed. No evidence for amplification of TS gene sequences was observed. The basis for the high levels of TS expression was examined by structural analysis of TS cDNA. No nucleotide sequence differences were detected in the coding regions of the TS genes from the metastases. Mutations were detected at positions 961 and/or 1031 in the 3'-untranslated regions of the TS gene from the metastases; mutations at these sites were also detected in DNA isolated from normal colon mucosa (n=4) and primary colorectal tumors (n=4). No correlation was observed between TS expression and the nucleotide alterations at these positions. Polymorphism was observed in the 5'-untranslated regions of the TS gene in hepatic metastases (n=6). A general trend was observed between the structure of the 5'-untranslated region of the gene and TS expression.
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PMID:Structural analysis of cDNA encoding thymidylate synthase in hepatic metastases of human colorectal tumors. 1168 31


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