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Forouzesh DC, Moran GR. Mammalian dihydropyrimidine dehydrogenase. Arch Biochem Biophys 2021; 714:109066. [PMID: 34717904 DOI: 10.1016/j.abb.2021.109066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/21/2021] [Accepted: 10/23/2021] [Indexed: 11/26/2022]
Abstract
Dihydropyrimidine dehydrogenase (DPD) catalyzes the two-electron reduction of pyrimidine bases uracil and thymine as the first step in pyrimidine catabolism. The enzyme achieves this simple chemistry using a complex cofactor set including two flavins and four Fe4S4 centers. The flavins, FAD and FMN, interact with respective NADPH and pyrimidine substrates and the iron-sulfur centers form an electron transfer wire that links the two active sites that are separated by 56 Å. DPD accepts the common antineoplastic agent 5-fluorouracil as a substrate and so undermines the establishment of efficacious toxicity. Though studied for multiple decades, a precise description of the behavior of the enzyme had remained elusive. It was recently shown that the active form of DPD has the cofactor set of FAD-4(Fe4S4)-FMNH2. This two-electron reduced state is consistent with fewer mechanistic possibilities and data suggests that the instigating and rate determining step in the catalytic cycle is reduction of the pyrimidine substrate that is followed by relatively rapid oxidation of NADPH at the FAD that, via the electron conduit of the 4(Fe4S4) centers, reinstates the FMNH2 cofactor for subsequent catalytic turnover.
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Affiliation(s)
- Dariush C Forouzesh
- Department of Chemistry and Biochemistry, 1068 W Sheridan Rd, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Graham R Moran
- Department of Chemistry and Biochemistry, 1068 W Sheridan Rd, Loyola University Chicago, Chicago, IL, 60660, USA.
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Forouzesh DC, Beaupre BA, Butrin A, Wawrzak Z, Liu D, Moran GR. The Interaction of Porcine Dihydropyrimidine Dehydrogenase with the Chemotherapy Sensitizer: 5-Ethynyluracil. Biochemistry 2021; 60:1120-1132. [PMID: 33755421 DOI: 10.1021/acs.biochem.1c00096] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dihydropyrimidine dehydrogenase (DPD) is a complex enzyme that reduces the 5,6-vinylic bond of pyrimidines, uracil, and thymine. 5-Fluorouracil (5FU) is also a substrate for DPD and a common chemotherapeutic agent used to treat numerous cancers. The reduction of 5FU to 5-fluoro-5,6-dihydrouracil negates its toxicity and efficacy. Patients with high DPD activity levels typically have poor outcomes when treated with 5FU. DPD is thus a central mitigating factor in the treatment of a variety of cancers. 5-Ethynyluracil (5EU) covalently inactivates DPD by cross-linking with the active-site general acid cysteine in the pyrimidine binding site. This reaction is dependent on the simultaneous binding of 5EU and nicotinamide adenine dinucleotide phosphate (NADPH). This ternary complex induces DPD to become activated by taking up two electrons from the NADPH. The covalent inactivation of DPD by 5EU occurs concomitantly with this reductive activation with a rate constant of ∼0.2 s-1. This kinact value is correlated with the rate of reduction of one of the two flavin cofactors and the localization of a mobile loop in the pyrimidine active site that places the cysteine that serves as the general acid in catalysis proximal to the 5EU ethynyl group. Efficient cross-linking is reliant on enzyme activation, but this process appears to also have a conformational aspect in that nonreductive NADPH analogues can also induce a partial inactivation. Cross-linking then renders DPD inactive by severing the proton-coupled electron transfer mechanism that transmits electrons 56 Å across the protein.
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Affiliation(s)
- Dariush C Forouzesh
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W Sheridan RoadChicago, Illinois 60660, United States
| | - Brett A Beaupre
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W Sheridan RoadChicago, Illinois 60660, United States
| | - Arseniy Butrin
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W Sheridan RoadChicago, Illinois 60660, United States
| | - Zdzislaw Wawrzak
- Synchrotron Research Center, Life Sciences Collaborative Access Team, Northwestern University, Argonne, Illinois 60439, United States
| | - Dali Liu
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W Sheridan RoadChicago, Illinois 60660, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1068 W Sheridan RoadChicago, Illinois 60660, United States
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Ding X, Chang VHS, Li Y, Li X, Xu H, Ho C, Ho D, Yen Y. Harnessing an Artificial Intelligence Platform to Dynamically Individualize Combination Therapy for Treating Colorectal Carcinoma in a Rat Model. ADVANCED THERAPEUTICS 2019. [DOI: 10.1002/adtp.201900127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Xianting Ding
- Institute for Personalized Medicine, State Key Laboratory of Oncogenes and Related Genes of Biomedical Engineering School Shanghai Jiao Tong University Shanghai 200030 China
| | - Vincent H. S. Chang
- Department of Physiology, School of Medicine, College of Medicine Taipei Medical University Taipei 110 Taiwan
- The PhD Program for Translational Medicine, College of Medical Science and Technology Taipei Medical University Taipei 110 Taiwan
| | - Yulong Li
- Institute for Personalized Medicine, State Key Laboratory of Oncogenes and Related Genes of Biomedical Engineering School Shanghai Jiao Tong University Shanghai 200030 China
| | - Xin Li
- Institute for Personalized Medicine, State Key Laboratory of Oncogenes and Related Genes of Biomedical Engineering School Shanghai Jiao Tong University Shanghai 200030 China
| | - Hongquan Xu
- Department of Statistics University of California Los Angeles CA 90095 USA
| | - Chih‐Ming Ho
- Department of Bioengineering, Henry Samueli School of Engineering and Applied Science University of California Los Angeles CA 90095 USA
- Department of Mechanical and Aerospace Engineering, Henry Samueli School of Engineering and Applied Science University of California Los Angeles CA 90095 USA
| | - Dean Ho
- The N.1 Institute for Health (N.1) National University of Singapore Singapore 117456
- Department of Biomedical Engineering, NUS Engineering National University of Singapore Singapore 117583
- Department of Pharmacology, Yong Loo Lin School of Medicine National University of Singapore Singapore 117600
| | - Yun Yen
- The PhD Program for Translational Medicine, College of Medical Science and Technology Taipei Medical University Taipei 110 Taiwan
- Chemical Engineering, Division of Chemistry and Chemical Engineering California Institute of Technology California 91125 USA
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Tsume Y, Amidon GL. Selection of suitable prodrug candidates for in vivo studies via in vitro studies; the correlation of prodrug stability in between cell culture homogenates and human tissue homogenates. JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES 2013; 15:433-46. [PMID: 22974791 DOI: 10.18433/j36k6z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE To determine the correlations/discrepancies of drug stabilities between in the homogenates of human culture cells and of human tissues. METHODS Amino acid/dipeptide monoester prodrugs of floxuridine were chosen as the model drugs. The stabilities (half-lives) of floxuridine prodrugs in human tissues (pancreas, liver, and small intestine) homogenates were obtained and compared with ones in cell culture homogenates (AcPC-1, Capan-2, and Caco-2 cells) as well as human liver microsomes. The correlations of prodrug stability in human small bowel tissue homogenate vs. Caco-2 cell homogenate, human liver tissue homogenate vs. human liver microsomes, and human pancreatic tissue homogenate vs. pancreatic cell, AsPC-1 and Capan-2, homogenates were examined. RESULTS The stabilities of floxuridine prodrugs in human small bowel homogenate exhibited the great correlation to ones in Caco-2 cell homogenate (slope = 1.0-1.3, r2 = 0.79-0.98). The stability of those prodrugs in human pancreas tissue homogenate also exhibited the good correlations to ones in AsPC-1 and Capan-2 cells homogenates (slope = 0.5-0.8, r2 = 0.58-0.79). However, the correlations of prodrug stabilities between in human liver tissue homogenates and in human liver microsomes were weaker than others (slope = 1.3-1.9, r2 = 0.07-0.24). CONCLUSIONS The correlations of drug stabilities in cultured cell homogenates and in human tissue homogenates were compared. Those results exhibited wide range of correlations between in cell homogenate and in human tissue homogenate (r2 = 0.07 - 0.98). Those in vitro studies in cell homogenates would be good tools to predict drug stabilities in vivo and to select drug candidates for further developments. In the series of experiments, 5'-O-D-valyl-floxuridine and 5'-O-L-phenylalanyl-L-tyrosyl-floxuridine would be selected as candidates of oral drug targeting delivery for cancer chemotherapy due to their relatively good stabilities compared to other tested prodrugs.
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Affiliation(s)
- Yasuhiro Tsume
- College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-1065, USA
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Zee YK, Goh BC, Lee SC. Pharmacologic modulation strategies to reduce dose requirements of anticancer therapy while preserving clinical efficacy. Future Oncol 2012; 8:731-49. [PMID: 22764771 DOI: 10.2217/fon.12.53] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Drug interactions may be exploited to overcome pharmacokinetic issues in order to improve the therapeutic index of a drug, with clinical goals of reducing the dose of the active drug while preserving efficacy or reducing toxicity. This strategy has been used in infectious disease and transplant medicine, and, more recently, in oncology. Pharmacologic modulation strategies range from coadministration of either a drug that inhibits a metabolizing enzyme that would inactivate the drug of interest, a drug that induces an enzyme that activates the drug of interest or a drug that inhibits transporters that affect the uptake or elimination of the drug of interest. This review will discuss pharmacologic modulation strategies that have been tested clinically in order to increase systemic drug exposure. Important examples include ketoconazole inhibition of hepatic CYP3A4 in order to increase systemic exposure to docetaxel, irinotecan and etoposide, and cyclosporine inhibition of intestinal ATP-binding cassette transporters in order to decrease the toxicity of irinotecan and increase the bioavailability of oral docetaxel, paclitaxel and topotecan.
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Affiliation(s)
- Ying-Kiat Zee
- Department of Haematology-Oncology, National University Cancer Institute, National University Health System, Singapore
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Potential of amino acid/dipeptide monoester prodrugs of floxuridine in facilitating enhanced delivery of active drug to interior sites of tumors: a two-tier monolayer in vitro study. Pharm Res 2011; 28:2575-88. [PMID: 21671137 DOI: 10.1007/s11095-011-0485-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 05/16/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE To evaluate the advantages of amino acid/dipeptide monoester prodrugs for cancer treatments by assessing the uptake and cytotoxic effects of floxuridine prodrugs in a secondary cancer cell monolayer following permeation across a primary cancer cell monolayer. METHODS The first Capan-2 monolayer was grown on membrane transwell inserts; the second monolayer was grown at the bottom of a plate. The permeation of floxuridine and its prodrugs across the first monolayer and the uptake and cell proliferation assay on secondary layer were sequentially determined. RESULTS All floxuridine prodrugs exhibited greater permeation across the first Capan-2 monolayer than the parent drug. The correlation between uptake and growth inhibition in the second monolayer with intact prodrug permeating the first monolayer suggests that permeability and enzymatic stability are essential for sustained action of prodrugs in deeper layers of tumors. The correlation of uptake and growth inhibition were vastly superior for dipeptide prodrugs to those obtained with mono amino acid prodrugs. CONCLUSIONS Although a tentative general overall correlation between intact prodrug and uptake or cytotoxic action was obtained, it appears that a mixture of floxuridine prodrugs with varying beneficial characteristics may be more effective in treating tumors.
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Czito BG, Hong TJ, Cohen DP, Petros WP, Tyler DS, Pappas TN, Yu D, Lee CG, Lockhart AC, Morse MA, Fernando N, Hurwitz HI. A phase I study of eniluracil/5-FU in combination with radiation therapy for potentially resectable and/or unresectable cancer of the pancreas and distal biliary tract. Cancer Invest 2006; 24:9-17. [PMID: 16466986 DOI: 10.1080/07357900500449454] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE Eniluracil is an effective inactivator of dihydropyrimidine dehydrogenase (DPD). It allows for oral dosing of 5-fluorouracil (5-FU), which may potentially improve the antitumor activity of 5-FU when delivered concurrently with radiotherapy while avoiding the inconvenience and morbidity of continuous infusion (CI) 5-FU. We addressed the safety of oral eniluracil/5-FU combined with radiation therapy and determined the profile of dose-limiting toxicities and recommended Phase II dose (RPTD) in patients with pancreatic and hepatobiliary cancers. METHODS AND MATERIALS Patients with resectable or locally advanced pancreatic and biliary cancer received eniluracil (starting at 6.0 mg/m(2) q12h)/5-FU (starting at 0.6 mg/m(2) q12h). Eniluracil/5-FU were given concurrently with preoperative radiation to 4500 cGy followed by 540 cGy by reduced fields. Surgery was considered 4 weeks after completion of therapy. RESULTS Thirteen patients were enrolled. Chemoradiotherapy was completed in all patients. The MTD was not reached and, thus, the RPTD of eniluracil/5-FU was determined to be 10 mg/m(2) q12h/1 mg/m(2) q12h. Two patients with locally advanced disease had a 30-45 percent cross-sectional tumor reduction, one of which underwent margin-negative resection. Two of 5 patients with pancreatic cancer, and 1 of 3 patients with cholangiocarcinoma, with underwent exploratory surgery had margin-negative resections. One patient had a pathologic complete response (pCR). Patient 5-FU plasma exposure increased slightly from Day 8 to Day 31. CONCLUSION Preoperative chemoradiation with oral eniluracil/5-FU is feasible, well tolerated, and potentially effective in the neoadjuvant setting. Further investigation of oral fluoropyrimidines as radiosensitizers for pancreaticobiliary malignancies is warranted.
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Affiliation(s)
- Brian G Czito
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
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Wright MA, Morrison G, Lin P, Leonard GD, Nguyen D, Guo X, Szabo E, Hopkins JL, Leguizamo JP, Harold N, Fioravanti S, Schuler B, Monahan BP, Saif MW, Quinn MG, Pang J, Grem JL. A phase I pharmacologic and pharmacogenetic trial of sequential 24-hour infusion of irinotecan followed by leucovorin and a 48-hour infusion of fluorouracil in adult patients with solid tumors. Clin Cancer Res 2005; 11:4144-50. [PMID: 15930350 DOI: 10.1158/1078-0432.ccr-04-2439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE In preclinical studies, sequential exposure to irinotecan (CPT-11) then fluorouracil (5-FU) is superior to concurrent exposure or the reverse sequence; a 24-hour infusion of CPT-11 may be better tolerated than shorter infusions. EXPERIMENTAL DESIGN CPT-11 was first given at four levels (70-140 mg/m(2)/24 hours), followed by leucovorin 500 mg/m(2)/0.5 hours and 5-FU 2,000 mg/m(2)/48 hours on days 1 and 15 of a 4-week cycle. 5-FU was then increased in three cohorts up to 3,900 mg/m(2)/48 hours. RESULTS Two patients had dose-limiting toxicity during cycle 1 at 140/3,900 of CPT-11/5-FU (2-week delay for neutrophil recovery; grade 3 nausea despite antiemetics); one of six patients at 140/3,120 had dose-limiting toxicity (grade 3 diarrhea, grade 4 neutropenia). Four of 22 patients with colorectal cancer had partial responses, two of which had prior bolus CPT-11/5-FU. The mean 5-FU plasma concentration was 5.1 micromol/L at 3,900 mg/m(2)/48 hours. The end of infusion CPT-11 plasma concentration averaged 519 nmol/L at 140 mg/m(2)/24 hours. Patients with UDP-glucuronosyltransferase (UGT1A1; TA)6/6 promoter genotype had a lower ratio of free to glucuronide form of SN-38 than in patients with >/=1 (TA)7 allele. Thymidylate synthase genotypes for the 28-base promoter repeat were 2/2 (13%), 2/3 (74%), 3/3 (13%); all four responders had a 2/3 genotype. CONCLUSIONS Doses (mg/m(2)) of CPT-11 140/24 hours, leucovorin 500/0.5 hours and 5-FU 3,120/48 hours were well tolerated.
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Affiliation(s)
- Maurice A Wright
- Medical Oncology Clinical Research Unit, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
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Fischel JL, Formento P, Ciccolini J, Etienne-Grimaldi MC, Milano G. Lack of contribution of dihydrofluorouracil and alpha-fluoro-beta-alanine to the cytotoxicity of 5'-deoxy-5-fluorouridine on human keratinocytes. Anticancer Drugs 2005; 15:969-74. [PMID: 15514566 DOI: 10.1097/00001813-200411000-00006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Capecitabine (Xeloda) is a very active oral fluoropyrimidine (colon and breast cancers) whose clinical use is complicated by the presence of hand-foot syndrome (HFS). This cutaneous toxicity is less frequently encountered with other oral fluoropyrimidines containing a dihydropyrimidine dehydrogenase (DPD) inhibitor. The HFS is thus attributed to the presence of the main 5-fluorouracil (5-FU) metabolites, dihydrofluorouracil (5-FUH2) and alpha-fluoro-beta-alanine (FBAL), but without strong pharmacological arguments. The aim of the present study was to closely examine this latter hypothesis. Capecitabine generates 5'-deoxyflourouridine (5'-DFUR) which is transformed into 5-FU at the cellular target site through the intermediary of thymidine phosphorylase (TP). The cytotoxic effects (MTT test, 4-day exposure) of 5'-DFUR, 5-FU, 5-FUH2 and FBAL were tested against the spontaneously immortalized human keratinocyte cell line (HaCaT) and the human cancer colon cell line WiDr as a control. Mean IC50s on HaCaT and WiDr were, respectively, 1.3 and 10 microM for 5'-DFUR, 0.2 and 3.3 microM for 5-FU, 13.4 and 560 microM for 5-FUH2, and greater than 650 and 6500 microM for FBAL. The respective 5'-DFUR IC50s values were not different when cells were exposed to 5'-DFUR alone or in combination with 5-FU, 5-FUH2 and FBAL in both cell lines, the relative proportion of each drug reflecting known pharmacokinetic data for capecitabine (5'-DFUR 12.4%, 5-FUH2 6.4%, 5-FU 1.2% and FBAL 80%). This latter finding demonstrates the relative lack of significant cytotoxic activity of 5-FUH2 and FBAL on human keratinocytes. TP activity was particularly high in HaCaT cells and DPD activity was very low in both cell lines. These data strongly suggest that the presence of 5-FU metabolites does not play a major role in the HFS generated by capecitabine and that it can probably be attributed to particularly high TP activity in keratinocytes. This observation may have important clinical consequences such as a possible local pharmacological inhibition of TP for controlling HFS.
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Affiliation(s)
- Jean-Louis Fischel
- Centre Antoine-Lacassagne, Nice, France; Pharmacy School, Marseille, France
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Bellibas SE, Patel I, Chamorey E, Brivet B, Bush ED, Kircher C, Nave S, Banken L, Renée N, Milano G. Single Ascending Dose Tolerability, Pharmacokinetic–Pharmacodynamic Study of Dihydropyrimidine Dehydrogenase Inhibitor Ro 09-4889. Clin Cancer Res 2004; 10:2327-35. [PMID: 15073108 DOI: 10.1158/1078-0432.ccr-03-0285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Ro 09-4889 was designed to enhance the anticancer efficacy of capecitabine (Xeloda) by generating a dihydropyrimidine dehydrogenase inhibitor (DPDi) 5-vinyluracil (5-VU) preferentially in tumor tissues. This study assessed the tolerance to Ro 09-4889 treatment, and related pharmacokinetic and pharmacodynamic data such as inhibition of DPD activity in peripheral blood mononuclear cells (PBMCs) and plasma uracil levels. EXPERIMENTAL DESIGN This was a single-center, double-blind, placebo-controlled, single-dose escalation study in 64 healthy male volunteers at 1-, 5-, 20-, 50-, 75-, 100-, and 200-mg oral dose of Ro 09-4889. Also, food effect was assessed separately in a group dosed with 20 mg of the compound. RESULTS No serious adverse effects or significant laboratory and electrocardiogram abnormalities were observed during the study. Ro 09-4889 has a short elimination half-life (t(1/2)) of 0.5 h, followed by metabolites 5'-deoxy-5-vinyluridine (5'-DVUR), 5'-deoxy-5-vinylcytidine (5'-DVCR), and 5-VU with t(1/2) of 1.3, 1.2, and 2 h, respectively. The major metabolite excreted in urine was 5-DVCR (45% of dose). The inhibition of PBMC DPD activity and the increase in plasma uracil were related to Ro 09-4889 dose. DPD inhibition versus dose and uracil AUC (area under the curve) versus dose were modeled using the E(max) model with a baseline effect. The model-predicted ED(50) value was 100 mg. CONCLUSION Single oral doses of Ro 09-4889 ranging from 1 to 200 mg were well tolerated. On the basis of these findings, a 10-to-30-mg dose range of Ro 09-4889 combined with capecitabine could be appropriate for further evaluation in cancer patients.
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Affiliation(s)
- S Eralp Bellibas
- Department of Clinical Pharmacology, Hoffmann-La Roche Inc., Nutley, New Jersey, USA
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Abstract
Changes in drug delivery as well as new drug development have impacted on cancer care in the past twenty years. Several modified release chemicals now have a role in cancer care, and new routes of drug delivery have been established as part of standard care. A range of strategies has been investigated to enhance anti-tumor selectivity of drugs including antibodies, liposomes and carrier molecules homing or activated in the environment of tumors. Fixed drug combinations are also used in cancer supportive care, and may find use in a range of settings.
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Affiliation(s)
- Martin Tattersall
- University of Sydney, Blackburn Building D06, Sydney, NSW 2006, Australia.
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Morgan-Meadows S, Thomas JP, Mulkerin D, Berlin JD, Bailey H, Binger K, Volkman J, Alberti D, Feierabend C, Marrocha R, Arzoomanian RZ, Wilding G. Phase I study of eniluracil, oral 5-fluororacil and gemcitabine in patients with advanced malignancy. Invest New Drugs 2002; 20:377-82. [PMID: 12448654 DOI: 10.1023/a:1020673928704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The objectives of this trial were to assess the maximal tolerated dose and toxicity of the combination of oral eniluracil and 5-fluorouracil and intravenous gemcitabine. PATIENTS AND METHODS Patients with histologically confirmed, incurable malignancy (solid tumor or lymphoma) refractory to standard therapy or for which no standard therapy exists were enrolled. The treatment plan consisted of weekly gemcitabine for three weeks with twice daily dosing of 5-FU and eniluracil for 21 days beginning on day one of gemcitabine. Cycles repeated on an every four week schedule. The initial cohort received gemcitabine 800 mg/m2, oral 5-FU 0.6 mg/m2 and eniluracil 6.0 mg/m2. RESULTS Twenty-six patients were enrolled. Eight patients received less than 2 cycles of therapy. Hematologic and gastrointestinal toxicity predominated, with 48% of courses resulted in grade one or two neutropenia. Hematologic toxicity was dose limiting. One treatment related death occurred. CONCLUSIONS The combination of eniluracil, 5-fluorouracil and gemcitabine offers an oral alternative for 5-FU administration. The recommended phase II dose is gemcitabine 1000 mg/m2, 5FU 1.2 mg/m2 and eniluracil 12 mg/m2.
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Saif MW, Wilson RH, Harold N, Keith B, Dougherty DS, Grem JL. Peripheral neuropathy associated with weekly oral 5-fluorouracil, leucovorin and eniluracil. Anticancer Drugs 2001; 12:525-31. [PMID: 11459999 DOI: 10.1097/00001813-200107000-00006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
5-Fluorouracil (5-FU)-associated neurotoxicity is uncommon; symptoms may occur abruptly or more gradually during the course of chemotherapy. Peripheral neuropathy with 5-FU therapy has only rarely been reported. Two patients treated in a phase I trial of oral 5-FU, leucovorin and eniluracil, an inhibitor of dihydropyrimidine dehydrogenase (DPD), developed delayed onset symptoms of unsteady gait and reduced sensation in the legs. Magnetic resonance imaging scans of the brain and neurologic examination did not support a CNS basis for the condition. Electromyograms and nerve conduction studies revealed sensorimotor polyneuropathy. Other common etiologies of peripheral neuropathy were excluded. The neurological condition of these patients stabilized after 5-FU dose reduction and partial resolution gradually occurred when protocol therapy was stopped. Although CNS symptoms may rarely complicate 5-FU therapy, peripheral neuropathy is unexpected. Patients with DPD deficiency treated with conventional doses of 5-FU typically develop acute CNS toxicity shortly after therapy, accompanied by extremely high systemic exposure to 5-FU. Patients with normal 5-FU clearance may also experience CNS toxicity, particularly with high-dose schedules, and both parent drug and its catabolites may be contributory. Since DPD was profoundly inhibited during eniluracil therapy in these two patients, it is likely that 5-FU or its active metabolites were contributing factors to the peripheral neuropathy.
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Affiliation(s)
- M W Saif
- Developmental Therapeutics Department, Medicine Branch, Division of Clinical Sciences, National Cancer Institute, National Institutes of Health, Bethesda, MD 20889, USA
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Affiliation(s)
- C H Takimoto
- Department of Medicine, Division of Medical Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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