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Oncotarget Nov 2017This network meta-analysis compared the short-term and long-term efficacies of first-line chemotherapy regimens in patients with advanced colorectal cancer (CRC). The 10...
This network meta-analysis compared the short-term and long-term efficacies of first-line chemotherapy regimens in patients with advanced colorectal cancer (CRC). The 10 regimens included folinic acid + 5-fluorouracil + oxaliplatin (FOLFOX), folinic acid + 5-fluorouracil + irinotecan (FOLFIRI), folinic acid + 5-fluorouracil + gemcitabine (FFG), folinic acid + 5-fluorouracil + trimetrexate (FFT), folinic acid + 5-fluorouracil (FF), irinotecan + oxaliplatin (IROX), raltitrexed + oxaliplatin (TOMOX), folinic acid + tegafur-uracil (FTU), raltitrexed, and capecitabine. Electronic searches were performed in the Cochrane Library, PubMed and Embase databases from inception to June 2017. Network meta-analysis combined direct and indirect evidence to obtain odds ratios (ORs) and surface under the cumulative ranking curves (SUCRA) of different chemotherapy regimens for advanced CRC. Fourteen randomized controlled trails (RCTs) covering 4,383 patients with advanced CRC were included. The results revealed that FOLFOX, FOLFIRI, IROX, and TOMOX all showed higher overall response rates (ORRs) than FF or raltitrexed. Compared with raltitrexed, the aforementioned four regimens also had higher 1-year progression-free survival (PFS) rates. In addition, FOLFOX and FOLFIRI exhibited higher disease control rates (DCRs) and 1-year PFS rates than FF or raltitrexed. Cluster analysis revealed that FOLFOX, FOLFIRI, and TOMOX had better short-term and long-term efficacies. These findings suggest FOLFOX, FOLFIRI, and TOMOX are superior to other regimens for advanced CRC. These three regimens are therefore recommended for clinical treatment of advanced CRC.
PubMed: 29246011
DOI: 10.18632/oncotarget.22177 -
British Journal of Cancer Dec 1994We examined the cytotoxicity and biochemical effects of the lipophilic antifol trimetrexate (TMQ) in two human colon carcinoma cell lines, SNU-C4 and NCI-H630, with...
We examined the cytotoxicity and biochemical effects of the lipophilic antifol trimetrexate (TMQ) in two human colon carcinoma cell lines, SNU-C4 and NCI-H630, with different inherent sensitivity to TMQ. While a 24 h exposure to 0.1 microM TMQ inhibited cell growth by 50-60% in both cell lines, it did not reduce clonogenic survival. A 24 h exposure to 1 and 10 microM TMQ produced 42% and 50% lethality in C4 cells, but did not affect H630 cells. Dihydrofolate reductase (DHFR) and thymidylate synthase were quantitatively and qualitatively similar in both lines. During drug exposure, DHFR catalytic activity was inhibited by > or = 85% in both cell lines; in addition, the reduction in apparent free DHFR binding capacity (< or = 20% of control), depletion of dTTP, ATP and GTP pools and inhibition of [6-3H]deoxyuridine incorporation into DNA were similar in C4 and H630 cells. TMQ produced a more striking alteration of the pH step alkaline elution profile of newly synthesised DNA in C4 cells compared with 630 cells, however, indicating greater interference with DNA chain elongation or more extensive DNA damage. When TMQ was removed after a 24 h exposure to 0.1 microM, recovery of DHFR catalytic activity and apparent free DHFR binding sites was evident over the next 24-48 h in both cell lines. With 1 and 10 microM, however, persistent inhibition of DHFR was evident in C4 cells, whereas DHFR recovered in H630 cells. These data suggest that, although DHFR inhibition during TMQ exposure produced growth inhibition, DHFR catalytic activity 48 h after drug removal was a more accurate predictor of lethality in these two cell lines. Several factors appeared to influence the duration of DHFR inhibition after drug removal, including initial TMQ concentration, declining cytosolic TMQ levels after drug removal, the ability to acutely increase total DHFR content and the extent of TMQ-mediated DNA damage. The greater sensitivity of C4 cells to TMQ-associated lethality may be attributed to the greater extent of TMQ-mediated DNA damage and more prolonged duration of DHFR inhibition after drug exposure.
Topics: Biological Transport; Cell Cycle; Cell Division; Cell Survival; Colorectal Neoplasms; DNA, Neoplasm; Humans; In Vitro Techniques; Tetrahydrofolate Dehydrogenase; Thymidylate Synthase; Thymine Nucleotides; Time Factors; Trimetrexate; Tumor Cells, Cultured
PubMed: 7981057
DOI: 10.1038/bjc.1994.451 -
Blood Nov 1997Antifolates such as methotrexate (MTX) and trimetrexate (TMTX) are widely used in the treatment of cancer and nonmalignant disorders. Transient, yet sometimes severe...
Antifolates such as methotrexate (MTX) and trimetrexate (TMTX) are widely used in the treatment of cancer and nonmalignant disorders. Transient, yet sometimes severe myelosuppression is an important limitation to the use of these drugs. It has previously been shown that clonogenic myeloid progenitors and colony-forming units-spleen are resistant to antifolates, suggesting that myelotoxicity occurs late in hematopoietic development. The goal of this study was to define the mechanisms by which primitive hematopoietic cells resist the toxic effects of antifolate drugs. To test the hypothesis that myeloid progenitors may salvage extracellular nucleotide precursors to resist TMTX toxicity, a defined liquid culture system was developed to measure TMTX toxicity in expanding progenitor populations. These in vitro experiments showed that both human and murine progenitors can resist TMTX toxicity by importing thymidine and hypoxanthine from the serum. As predicted from these findings, several drugs that block thymidine transport sensitized progenitors to TMTX in vitro, although to differing degrees. These nucleoside transport inhibitors were used to test whether progenitors and hematopoietic stem cells (HSCs) could be sensitized to TMTX in vivo. Treatment of mice with TMTX and nitrobenzylmercaptopurineriboside phosphate (NBMPR-P), a potent transport inhibitor, caused significant depletions of clonogenic progenitors within the bone marrow (20-fold) and spleen (6-fold). Furthermore, NBMPR-P administration dramatically sensitized HSCs to TMTX, with dual-treated mice showing a greater than 90% reduction in bone marrow repopulating activity. These studies demonstrate that both myeloid progenitor cells and HSCs resist TMTX by using nucleotide salvage mechanisms and that these pathways can be pharmacologically blocked in vivo using nucleoside transport inhibitors. These results have important implications regarding the use of transport inhibitors for cancer therapy and for using variants of dihydrofolate reductase for in vivo selection of genetically modified HSCs.
Topics: Animals; Antimetabolites, Antineoplastic; Biological Transport; Cell Death; Drug Resistance, Neoplasm; Female; Hematopoietic Stem Cells; Humans; Mice; Mice, Inbred C57BL; Thioinosine; Thionucleotides; Thymidine; Trimetrexate
PubMed: 9345038
DOI: No ID Found -
PLoS Neglected Tropical Diseases May 2016Bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) is a chemically and genetically validated target in African trypanosomes, causative agents of...
Bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) is a chemically and genetically validated target in African trypanosomes, causative agents of sleeping sickness in humans and nagana in cattle. Here we report the kinetic properties and sensitivity of recombinant enzyme to a range of lipophilic and classical antifolate drugs. The purified recombinant enzyme, expressed as a fusion protein with elongation factor Ts (Tsf) in ThyA- Escherichia coli, retains DHFR activity, but lacks any TS activity. TS activity was found to be extremely unstable (half-life of 28 s) following desalting of clarified bacterial lysates to remove small molecules. Stability could be improved 700-fold by inclusion of dUMP, but not by other pyrimidine or purine (deoxy)-nucleosides or nucleotides. Inclusion of dUMP during purification proved insufficient to prevent inactivation during the purification procedure. Methotrexate and trimetrexate were the most potent inhibitors of DHFR (Ki 0.1 and 0.6 nM, respectively) and FdUMP and nolatrexed of TS (Ki 14 and 39 nM, respectively). All inhibitors showed a marked drop-off in potency of 100- to 1,000-fold against trypanosomes grown in low folate medium lacking thymidine. The most potent inhibitors possessed a terminal glutamate moiety suggesting that transport or subsequent retention by polyglutamylation was important for biological activity. Supplementation of culture medium with folate markedly antagonised the potency of these folate-like inhibitors, as did thymidine in the case of the TS inhibitors raltitrexed and pemetrexed.
Topics: Animals; Enzyme Stability; Folic Acid Antagonists; Multienzyme Complexes; Rats; Rats, Wistar; Recombinant Fusion Proteins; Tetrahydrofolate Dehydrogenase; Thymidylate Synthase; Trypanosoma brucei brucei
PubMed: 27175479
DOI: 10.1371/journal.pntd.0004714 -
ACS Infectious Diseases Dec 2015Antifolates are widely used to treat several diseases but are not currently used in the first-line treatment of tuberculosis, despite evidence that some of these...
Antifolates are widely used to treat several diseases but are not currently used in the first-line treatment of tuberculosis, despite evidence that some of these molecules can target Mycobacterium tuberculosis (Mtb) bacilli in vitro. To identify new antifolate candidates for animal-model efficacy studies of tuberculosis, we paired knowledge and tools developed in academia with the infrastructure and chemistry resources of a large pharmaceutical company. Together we curated a focused library of 2508 potential antifolates, which were then tested for activity against live Mtb. We identified 210 primary hits, confirmed the on-target activity of potent compounds, and now report the identification and characterization of 5 hit compounds, representative of 5 different chemical scaffolds. These antifolates have potent activity against Mtb and represent good starting points for improvement that could lead to in vivo efficacy studies.
PubMed: 26771003
DOI: 10.1021/acsinfecdis.5b00063 -
Methods and Findings in Experimental... Dec 2010Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables has been retrieved from...
Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables has been retrieved from the Clinical Trials Knowledge Area of Thomson Reuters Integrity(SM), the drug discovery and development portal, http://www.thomsonreutersintegrity.com. This issue focuses on the following selection of drugs: 17-Hydroxyprogesterone caproate; Abacavir sulfate/lamivudine, Aclidinium bromide, Adalimumab, Adefovir, Alemtuzumab, Alkaline phosphatase, Amlodipine, Apilimod mesylate, Aripiprazole, Axitinib, Azacitidine; Belotecan hydrochloride, Berberine iodide, Bevacizumab, Bortezomib, Bosentan, Bryostatin 1; Calcipotriol/hydrocortisone, Carglumic acid, Certolizumab pegol, Cetuximab, Cinacalcet hydrochloride, Cixutumumab, Coumarin, Custirsen sodium; Darbepoetin alfa, Darifenacin hydrobromide, Darunavir, Dasatinib, Denibulin hydrochloride, Denosumab, Diacetylmorphine, Dulanermin, Duloxetine hydrochloride; Ecogramostim, Enfuvirtide, Entecavir, Enzastaurin hydrochloride, Eplerenone, Escitalopram oxalate, Esomeprazole sodium, Etravirine, Everolimus, Ezetimibe; Fenofibrate/pravastatin sodium, Ferric carboxymaltose, Flavangenol, Fondaparinux sodium; Glutamine, GSK-1024850A; Hepatitis B hyperimmunoglobulin, Hib-MenC, HIV-LIPO-5; Immunoglobulin intravenous (human), Indacaterol maleate, Indibulin, Indium 111 (¹¹¹In) ibritumomab tiuxetan, Influenza A (H1N1) 2009 Monovalent vaccine, Inhalable human insulin, Insulin glulisine; Lapatinib ditosylate, Leucovorin/UFT; Maraviroc, Mecasermin, MMR-V, Morphine hydrochloride, Morphine sulfate/naltrexone hydrochloride, Mycophenolic acid sodium salt; Naproxen/esomeprazole magnesium, Natalizumab; Oncolytic HSV; Paliperidone, PAN-811, Paroxetine, Pegfilgrastim, Peginterferon alfa-2a, Peginterferon alfa-2b/ribavirin, Pegvisomant, Pemetrexed disodium, Pimecrolimus, Posaconazole, Pregabalin; Raltegravir potassium, Ranelic acid distrontium salt, Rasburicase, Rilpivirine hydrochloride; Sertindole, Sivelestat sodium hydrate, Sorafenib, Sumatriptan succinate/naproxen sodium, Sunitinib malate; Tafluprost, Telithromycin, Temsirolimus, Tenofovir disoproxil fumavate, Tenofovir disoproxil fumarate/emtricitabine, Teriparatide, Ticagrelor, Tigecycline, Tipranavir, Tirapazamine, Trimetrexate; Ulipristal acetate; Valganciclovir hydrochloride, Vicriviroc, Vorinostat; Yttrium 90 (90Y) ibritumomab tiuxetan.
Topics: Clinical Trials as Topic; Humans
PubMed: 21225012
DOI: 10.1358/mf.2010.32.10.1573763 -
Frontiers in Bioscience (Scholar... Jan 2010This article presents a case-study review of synergy concepts of nonlinear blending and dose-reduction profiles. "Strong nonlinear blending" is a novel concept that... (Review)
Review
This article presents a case-study review of synergy concepts of nonlinear blending and dose-reduction profiles. "Strong nonlinear blending" is a novel concept that provides a flexible paradigm for the assessment of combination drug synergy that is applicable to any shaped combination-drug dose-response surface; issues of varying relative potency, partial inhibitors, potentiation, or coalism pose no problems at all. Dose-reduction profiles are overlay plots created to show how much each drug can be reduced in amount and yet achieve the same efficacy as larger amounts of each drug used individually. This review applies these synergy concepts to two data sets from a previously published experiment. The previous publication had claimed a high degree of Loewe synergy for one of the data sets. However, a more penetrating analysis shows that with regard to strong nonlinear blending there is no reason to blend (for purposes of response enhancement) the two compounds studied. However, the dose-reduction profile plots show how Loewe synergy is present and provide further insight to the interaction of the two compounds (on the dose-concentration scale).
Topics: Dose-Response Relationship, Drug; Drug Combinations; Drug Synergism; Folic Acid; Glutamates; Models, Theoretical; Pyrimidines; Trimetrexate
PubMed: 20036963
DOI: 10.2741/s80 -
The Journal of Biological Chemistry Nov 1989We describe the development of resistance to trimetrexate and piritrexim (BW 301U) by a stepwise selection protocol in Chinese hamster ovary cells. Selection in... (Comparative Study)
Comparative Study
Sequential amplification of dihydrofolate reductase and multidrug resistance genes in Chinese hamster ovary cells selected for stepwise resistance to the lipid-soluble antifolate trimetrexate.
We describe the development of resistance to trimetrexate and piritrexim (BW 301U) by a stepwise selection protocol in Chinese hamster ovary cells. Selection in trimetrexate resulted in initial resistance as a result of dihydrofolate reductase gene amplification. Several trimetrexate-resistant variants that display 250-340-fold and 25-50-fold resistance to lipophilic and hydrophilic antifolates, respectively, were established. Increased antifolate resistance was associated with a prominent overexpression of dihydrofolate reductase as determined from the elevated folate reductase activity, cellular labeling with fluorescein-methotrexate, and steady-state mRNA levels as a result of a consistent dihydrofolate reductase gene amplification. However, upon subsequent incremental increases in trimetrexate, further resistance was also associated with amplification of the multidrug resistance gene. This resulted in overexpression of P-glycoprotein and a subsequent 20-50-fold collateral resistance to pleiotropic drugs such as adriamycin, actinomycin D, vinca alkaloids, etoposide, and colchicine. In contrast, initial resistance following selection with low piritrexim concentrations resulted from an unknown mechanism(s) not involving overproduction of either dihydrofolate reductase or P-glycoprotein. This piritrexim resistance was shared with trimetrexate but not with methotrexate. Upon further selection with piritrexim, resistant variants emerge with amplified dihydrofolate reductase but not with multidrug resistance genes. These variants were subsequently resistant to both hydrophilic and lipophilic folate antagonists but retained sensitivity to pleiotropic drugs. The pattern of resistance with methotrexate, trimetrexate, and piritrexim shared a common mechanism, dihydrofolate reductase gene amplification, but differed regarding the additional amplification of the multidrug resistance gene in trimetrexate-resistant cells as well as the emergence of an additional unknown mechanism(s) of resistance to lipid-soluble antifolates upon initial selection in piritrexim.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Cell Line; Cricetinae; Drug Resistance; Fluorescein; Fluoresceins; Folic Acid Antagonists; Gene Amplification; Gene Expression; Membrane Glycoproteins; Methotrexate; Pyrimidines; Quinazolines; RNA, Messenger; Tetrahydrofolate Dehydrogenase; Trimetrexate
PubMed: 2572592
DOI: No ID Found -
Anticancer Research 2006Currently, one of the most effective strategies for the treatment and prevention of breast cancer is the use of drugs that block estrogen action in the breast. The...
BACKGROUND
Currently, one of the most effective strategies for the treatment and prevention of breast cancer is the use of drugs that block estrogen action in the breast. The success of the first clinically relevant selective estrogen receptor modulator (SERM), tamoxifen, provided the foundation for further testing of this drug to reduce breast cancer incidence in high-risk women. However, the negative effects associated with the long-term use of tanrhoxifen have initiated the search for compounds that are more effective but less toxic. The discovery of raloxifene (RAL), which functions as a potent antiestrogen in the breast but an estrogen receptor (ER) agonist in the bone and cardiovascular system with very little uterotropic activity, provided an alternative strategy to the targeted use of tamoxifen. The aim of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU)/trimetrexate (TMX) to determine the most effective regimes and cellular mechanism of action to mitigate trimetrexate cytotoxicity in human bone marrow cells.
MATERIALS AND METHODS
The cell viability was performed using the Quick Cell Proliferation Assay by exposing the cells to TMX, 5-FU and RAL alone; RAL 24 h prior to 5-FU followed 2 h by TMX, and 5-FU 2 h prior to TMX followed 24 h by RAL determined the sequence-dependent interaction between TMX, 5-FU and RAL on the proliferation.
RESULTS
The growth rate in MCF-7 in late RAL was 34.75 +/- 4.79% of the control, whereas in bone marrow the same drug combination exhibits a significant protection against TMX cytotoxicity with late RAL yielding 51.25 +/- 4.43% of the control. The findings were also supported by Cell flow cytometry and Western blot analysis.
CONCLUSION
Sequence-dependent administration of RAL in combination with 5-FU/TMX can act against TMX toxicity in human bone marrow, while not affecting the maximum inhibitory effect of TMX in breast cancer.
Topics: Antineoplastic Agents; Bone Marrow; Breast Neoplasms; Cell Line, Tumor; Fluorouracil; Humans; Raloxifene Hydrochloride; Trimetrexate
PubMed: 17201145
DOI: No ID Found -
Blood Nov 1999Cellular methotrexate (MTX) resistance may cause treatment failure in childhood common/preB-acute lymphoblastic leukemia (c/preB-ALL), T-lineage ALL (T-ALL), and acute...
Cellular methotrexate (MTX) resistance may cause treatment failure in childhood common/preB-acute lymphoblastic leukemia (c/preB-ALL), T-lineage ALL (T-ALL), and acute myeloid leukemia (AML). The ex vivo potency of several antifolates (MTX, trimetrexate [TMQ], GW1843U89, multitargeted antifolate [MTA], Raltitrexed, and ZD9331) was studied via in situ inhibition of thymidylate synthase (TS). After short-term exposure, relapsed c/preB-ALL (rALL, n = 21), T-ALL (n = 22), and AML (n = 22) were 3-fold, 10-fold, and 6-fold less sensitive to MTX (P =.01) compared with initial c/preB-ALL (n = 43). This difference in resistance was not observed for TMQ. Also for GW1843U89 and MTA, no resistance was observed in rALL and AML compared with c/preB-ALL. T-ALL compared with c/preB-ALL tended to be less resistant to GW1843U89 (3-fold) and MTA (6-fold) than to MTX (10-fold) (P =.06). Raltitrexed was more active against c/preB-ALL compared with the other subtypes. After 21 hours continuous incubation, T-ALL and AML samples were equally sensitive as c/preB-ALL to MTX, but rALL was 3-fold resistant to MTX compared with initial c/preB-ALL (P =.003). The resistance of rALL was circumvented by TMQ (1-fold; P =.03) and GW1843U89 (1.4-fold; P =. 004). Novel antifolates, except MTA, displayed a more potent TS inhibition than MTX during continuous exposure. These results suggest that MTX resistance in AML and T-ALL can be circumvented by continuous exposure, and that novel antifolates should be explored further for MTX-resistant T-ALL, rALL, and AML cells.
Topics: Antimetabolites, Antineoplastic; Child; Child, Preschool; Drug Resistance, Neoplasm; Folic Acid Antagonists; Humans; Leukemia; Methotrexate; Quinazolines; Thiophenes; Treatment Outcome; Trimetrexate
PubMed: 10556198
DOI: No ID Found