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Naunyn-Schmiedeberg's Archives of... Mar 1997We have previously reported that the histaminergic system is involved in the control of pain perception, and that substances able to enhance histamine brain levels, such...
We have previously reported that the histaminergic system is involved in the control of pain perception, and that substances able to enhance histamine brain levels, such as the histamine-N-methyltransferase inhibitor, metoprine, induce antinociception. In the present study, in order to corroborate the idea of inducing antinociception by inhibiting histamine catabolism, the effects of a noncompetitive histamine-N-methyltransferase inhibitor. SKF 91488, were studied in rodents by means of tests inducing three different kinds of noxious stimuli: thermal (mouse hot plate), chemical (mouse abdominal constrictions) and mechanical (rat paw pressure). The ability to react to noxious stimuli was assessed by the rota-rod test. In addition, a competitive inhibitor of the histamine catabolism enzyme, BW 301 U, was studied in the hot plate test. SKF 91488 (30, 50 and 100 micrograms per animal i.c.v.) raised dose-dependently the pain threshold in all three tests. To verify whether SKF 91488-induced antinociception is due to inhibition of histamine-N-methyltransferase, (R)-alpha-methylhistamine, described to block histamine release and synthesis by stimulating the histamine H3-autoreceptor and activating the negative feed-back mechanism, was used. When administered at doses which do not alter the pain threshold per se, 0.5 microgram per rat i.c.v. or 10 mg kg-1 i.p. in mice, (R)-alpha-methylhistamine was able to antagonize significantly the antinociceptive effect induced by 30 micrograms per animal i.c.v. of SKF 91488. BW 301 U (30 and 100 mg kg-1 i.p.) showed a dose-dependent, long-lasting antinociception, which was also antagonized by pretreatment with (R)-alpha-methylhistamine. The present data show that the antinociceptive effect previously described for metoprine is not restricted to this molecule, but is also shared by other histamine-N-methyl-transferase inhibitors. This generalization provides further evidence to the importance of the histaminergic system in pain control mechanisms.
Topics: Analgesics; Animals; Dimaprit; Dose-Response Relationship, Drug; Enzyme Inhibitors; Folic Acid Antagonists; Histamine Agonists; Histamine N-Methyltransferase; Injections, Intraventricular; Male; Methylhistamines; Mice; Muscle Contraction; Pain Measurement; Postural Balance; Psychomotor Performance; Pyrimidines; Rats; Rats, Wistar
PubMed: 9089666
DOI: 10.1007/pl00004954 -
Journal of the National Cancer Institute Feb 1997Thymidylate synthase (TS), an essential enzyme in DNA synthesis, is a target for the fluoropyrimidines, an important group of antineoplastic agents used widely in the...
BACKGROUND
Thymidylate synthase (TS), an essential enzyme in DNA synthesis, is a target for the fluoropyrimidines, an important group of antineoplastic agents used widely in the treatment of head and neck cancer.
PURPOSE
We evaluated relationships between the level and/or pattern of tumor TS expression and response to fluorouracil (5-FU)-based neoadjuvant chemotherapy in patients with advanced head and neck cancer.
METHODS
Tumor specimens from 86 patients were available for this retrospective analysis. The patients were enrolled in four consecutive phase II studies that tested combinations of 5-FU, leucovorin, and cisplatin with or without added methotrexate plus piritrexim or interferon alfa-2b (IFN alpha-2b). TS protein expression in the tumors was assessed by use of the TS 106 monoclonal antibody and standard immunohistochemical staining techniques. TS immunostaining was classified according to its level of intensity (TS 0-1 = low, TS 2 = intermediate, and TS 3 = high) and according to its extent (focal pattern = less than 25% of tumor cells positive; diffuse pattern = greater than or equal to 25% of tumor cells positive). Data from 79 patients were available for an analysis of tumor TS expression and patient/tumor characteristics; 70 patients were assessable for their response to neoadjuvant chemotherapy.
RESULTS
There was a statistically significant association between the level of tumor TS expression and the degree of tumor differentiation; a higher proportion of patients whose tumors exhibited TS 0-1 immunostaining had undifferentiated or poorly differentiated tumors than patients whose tumors exhibited TS 2 or TS 3 immunostaining (P = .04, Jonckheere-Terpstra trend test). Among the 70 patients who were assessable for response to neoadjuvant chemotherapy, TS 3 tumor immunostaining was associated with a lower rate of complete response (i.e., complete disappearance of clinically detectable disease for a minimum of 4 weeks from time of initial determination) than was TS 2 or TS 0-1 immunostaining, but this association was not statistically significant (P = .09, exact trend test); among the 39 patients who were treated with regimens that included 5-FU, leucovorin, cisplatin, and IFN alpha-2b, this inverse association between TS immunostaining intensity and response was statistically significant (P = .02, exact trend test). Tumor TS immunostaining intensity and overall survival were not found to be associated. Patients with tumors exhibiting a focal pattern of TS immunostaining have experienced significantly longer survival than patients with tumors exhibiting a diffuse pattern; for the 53 patients with diffuse tumor TS immunostaining, the median survival was 24.7 months, whereas the median survival has not yet been reached for the 22 patients with focal tumor TS immunostaining (P = .04, two-tailed logrank test). However, the survival advantage for the focal versus diffuse TS immunostaining pattern was limited to patients whose tumors also exhibited a TS 3 level of immunostaining intensity.
CONCLUSIONS AND IMPLICATIONS
Characterization of tumor TS expression may be of value in identifying patients with advanced head and neck cancer who would benefit from fluoropyrimidine-based neoadjuvant chemotherapy.
Topics: Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Chemotherapy, Adjuvant; Cisplatin; Dihydrouracil Dehydrogenase (NADP); Fluorouracil; Gene Expression Regulation, Neoplastic; Head and Neck Neoplasms; Humans; Immunohistochemistry; Interferon alpha-2; Interferon-alpha; Leucovorin; Oxidoreductases; Predictive Value of Tests; Recombinant Proteins; Remission Induction; Retrospective Studies; Thymidylate Synthase; Treatment Outcome
PubMed: 9048835
DOI: 10.1093/jnci/89.4.308 -
Journal of Medicinal Chemistry Feb 1997Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2-10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase...
Synthesis and biological evaluation of nonclassical 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines with novel side chain substituents as potential inhibitors of dihydrofolate reductases.
Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2-10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase (pcDHFR) and Toxoplasma gondii dihydrofolate reductase (tgDHFR). Compounds 2-5 were designed as conformationally restricted analogues of trimetrexate (TMQ), in which rotation around tau 3 was constrained by incorporation of the side chain nitrogen as part of an indoline or an indole ring. Analogue 6, which has an extra atom between the side chain nitrogen and the phenyl ring, has its nitrogen as part of a tetrahydroisoquinoline ring. Analogues 7-9 are epiroprim (Ro 11-8958) analogues and contain a pyrrole ring as part of the side chain substitution on the phenyl ring similar to epiroprim. These analogues were designed to investigate the role of the pyrrole substitution on the phenyl ring of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines. Molecular modeling indicated that a pyrrole substituent in the ortho position of the side chain phenyl ring was most likely to interact with pcDHFR in a manner similar to the pyrrole moiety of epiroprim. Analogue 10, in which a phenyl ring replaced a methoxy group, was synthesized to determine the contribution of a phenyl ring on selectivity, lipophilicity, and cell penetration. The synthesis of analogues 2-4 was achieved via reductive amination of 2,4-diamino-5-methyl 6-carboxaldehyde with the appropriately substituted indolines. The indolines were obtained from the corresponding indoles via NaCNBH3 reductions. Analogues 5-10 were synthesized by nucleophilic displacement of 2,4-diamino-5-methyl-6-(bromomethyl)-pyrido[2,3-d]pyrimidine with the 5-methoxyindolyl anion, 6,7-dimethoxytetrahydroisoquinoline, the appropriately substituted pyrroloaniline or 2-methoxy-5-phenylaniline. The pyrroloanilines were synthesized in two steps by treating the substituted nitroanilines with 2,5-dimethoxy-tetrahydrofuran to afford the nitropyrrole intermediates, followed by reduction of the nitro group with Raney Ni. The analogues were more potent than trimethoprim and epiroprim and more selective than TMQ and piritrexim against pcDHFR and tgDHFR. Compounds 5 and 10 had IC50 values of 1 and 0.64 microM, respectively, for the inhibition of the growth of T. gondii cells in culture, and showed excellent culture IC50/enzyme IC50 ratios, which were correlated with their calculated log P values, indicating a direct relationship between calculated lipophilicity and cell penetration.
Topics: AIDS-Related Opportunistic Infections; Animals; Folic Acid Antagonists; Humans; Liver; Mice; Pneumocystis; Pyrimidines; Rats; Tetrahydrofolate Dehydrogenase; Toxoplasma; Trimetrexate
PubMed: 9046338
DOI: 10.1021/jm960734f -
Journal of Medicinal Chemistry Feb 1997Two series of nonclassical antifolates (2,4-diamino-5-deaza compounds 2-5 and 5,10-dideaza compounds 6-13) were synthesized as inhibitors of dihydrofolate reductase...
Two series of nonclassical antifolates (2,4-diamino-5-deaza compounds 2-5 and 5,10-dideaza compounds 6-13) were synthesized as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) organisms that are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity. Syntheses of the target 5-deaza compounds were achieved by initial construction of the pivaloyl-protected 2,4-diamino-6-bromopyrido[2,3-d]-pyrimidine 17 via a cyclocondensation of 2,4,6-triaminopyrimidine with bromomalonaldehyde. Sequential Heck coupling of 17 with styrene followed by ozonolysis afforded the 6-formyl derivative 19. Reductive amination of 19 with 3,4,5-trimethoxyaniline afforded the N10-H analog. The N10-Me and N10-Et analogs were synthesized by nucleophilic displacement of the 6-bromomethyl derivative 22 (obtained from the 6-formyl derivative 19 by reduction and bromination) with the appropriate N-alkylaniline. The trans-5,10-dideaza analogs 6-8 were synthesized via a Heck coupling of the appropriate methoxystyrene with 17, and selective reduction of the resulting 9,10-double bond afforded target compounds 9-11. Further reduction to the tetrahydro derivatives afforded analogs 12 and 13. The 5-deaza N10-Me 3,4,5-trimethoxy analog 3 maintained the best balance of potency and selectivity against both tgDHFR and pcDHFR. Compared to trimethoprim, compound 3 was only slightly less selective but was 300-fold more potent against tgDHFR. The 5,10-dideaza analogs were generally less potent and selective than the 5-deaza compounds.
Topics: AIDS-Related Opportunistic Infections; Animals; Folic Acid Antagonists; Liver; Pyrimidines; Rats; Tetrahydrofolate Dehydrogenase; Trimetrexate
PubMed: 9046337
DOI: 10.1021/jm9606913 -
Investigational New Drugs 1997Oral piritrexim (PTX), a second generation antimetabolite, has been shown to be an active agent against methotrexate refractory transitional cell cancer (TCC) of the... (Clinical Trial)
Clinical Trial
UNLABELLED
Oral piritrexim (PTX), a second generation antimetabolite, has been shown to be an active agent against methotrexate refractory transitional cell cancer (TCC) of the bladder in phase I trials. We conducted a phase II trial of this drug in patients with TCC of the bladder who failed a first line chemotherapy regimen.
METHODS
Oral PTX was started at the dose of 25 mg three times per day for 5 days weekly for 3 weeks followed by one week of rest. If this was tolerated the dose was increased to 50 mg three times a day. Patients were monitored for response rate and toxicity.
RESULTS
Seventeen patients were entered into the trial. Two patients did not complete the required 2 courses of treatment to be evaluable. There were 13 evaluable patients. Among the 13 no one achieved a complete response (CR), however, there were 3 partial responses (PRs = RR: 23%) and 5 stable diseases (SDs). The responses lasted 2, 8 and 14 months. The major dose-limiting toxicity was myelosuppression. Two patients died on treatment. One death was due to neutropenic fever and the cause of death in the second patient is thought to be a cerebral vascular accident (CVA).
CONCLUSION
PTX is an active drug in the treatment of TCC of the bladder. Bone marrow suppression is the most common dose-limiting toxicity. In view of the observed responses and toxicities in this study and other studies, we suggest that the role of PTX be further investigated in the following clinical settings: 1. Palliative initial treatment in patients with TCC of the bladder who are not candidates for more aggressive chemotherapy. 2. As first line chemotherapy in combination with other active drugs.
Topics: Administration, Oral; Aged; Antimetabolites, Antineoplastic; Carcinoma, Transitional Cell; Drug Administration Schedule; Female; Humans; Male; Middle Aged; Pyrimidines; Urinary Bladder Neoplasms
PubMed: 9220296
DOI: 10.1023/a:1005860806635 -
Seminars in Oncology Oct 1996For the past 10 years, chemotherapy for advanced urothelial carcinoma has centered on cisplatin-based combination regimens such as methotrexate, vinblastine, doxorubicin... (Review)
Review
For the past 10 years, chemotherapy for advanced urothelial carcinoma has centered on cisplatin-based combination regimens such as methotrexate, vinblastine, doxorubicin and cisplatin (MVAC). Although such regimens have provided modest improvements in response rates, time to progression and survival, this has been achieved with moderate to severe toxicity. The median survival of patients with advanced disease remains at 12 to 13 months, and attempts to increase the dose intensity of existing regimens have been unsuccessful. Increasingly, attention has turned to the identification of new active agents, and a number have been recently identified, including paclitaxel, gemcitabine, ifosfamide, trimetrexate, piritrexim, and gallium nitrate. These agents will form the basis of new combination regimens that will attempt to improve on the advances in response and survival achieved with combination chemotherapy during the past decade.
Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Humans; Urinary Bladder Neoplasms
PubMed: 8893874
DOI: No ID Found -
Antimicrobial Agents and Chemotherapy May 1996The anti-Pneumocystis carinii drug effects on mitogen-, antigen-, and interleukin-2-induced proliferative responses and on natural killer (NK) cell-mediated activity...
The anti-Pneumocystis carinii drug effects on mitogen-, antigen-, and interleukin-2-induced proliferative responses and on natural killer (NK) cell-mediated activity were analyzed in vivo (rats) and in vitro (normal human peripheral blood mononuclear cells). Splenocytes derived from in vivo piritrexim- and clindamycin-treated rats showed a significant inhibition of mitogen-induced proliferative responses. In vitro exposure to clindamycin, piritrexim, and pyrimethamine caused an inhibition of human T lymphocyte proliferation in response to mitogen, antigen, and interleukin-2 stimulation. Rat NK cell-mediated cytotoxic activity was not affected by the drugs, and human NK cell activity was reduced only at the highest concentration (10 micrograms/ml) of the drugs. The potential immunotoxicity of the long-term administration of these agents in humans needs further investigation.
Topics: Adjuvants, Immunologic; Animals; Anti-Infective Agents; Antigens, Fungal; Cells, Cultured; Clindamycin; Cytotoxicity, Immunologic; Folic Acid Antagonists; Humans; Interleukin-2; Killer Cells, Natural; Lymphocyte Activation; Male; Mitogens; Monocytes; Pyrimethamine; Pyrimidines; Rats; Rats, Sprague-Dawley; Spleen; T-Lymphocytes
PubMed: 8723488
DOI: 10.1128/AAC.40.5.1294 -
Journal of Medicinal Chemistry Mar 19962,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four...
Lipophilic antifolates as agents against opportunistic infections. 1. Agents superior to trimetrexate and piritrexim against Toxoplasma gondii and Pneumocystis carinii in in vitro evaluations.
2,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four 2,4-diaminoquinazolines, each with an aryl groups attached to the 6-position of the heterocyclic moiety through a two-atom bridge (either CH2NH, CH2N(CH3),CH2S, or CH2CH2), were synthesized and evaluated as inhibitors of the growth of Toxoplasma gondii in culture and as inhibitors of dihydrofolate reductase enzymes from T. gondii, Pneumocystis carinii, and rat liver. Exceptionally high levels of combined potency and selectivity as growth inhibitors of T. gondii and as inhibitors of the microbial enzymes relative to the mammalian enzyme were found among the 5-methyl-5-deazapteridines but not for the other heterocyclic types. Thirty of the 34 5-methyl-5-deaza compounds gave growth inhibition IC50 values lower than that of pyrimethamine (0.4 microM) with 14 compounds below 0.1 microM, values that compare favorably with those for piritrexim and trimetrexate (both near 0.02 microM). As inhibitors of T gondii DHFR, all but three of the 34 5-methyl-5-deaza compounds gave IC50 values in the order of magnitude with those of piritrexim (0.017 microM) and trimetrexate (0.010 microM), and 17 compounds of this group gave IC50 values versus P. carinii DHFR similarly comparable with those of piritrexim (0.031 microM) and trimetrexate (0.042 microM). Thirteen of these congeners gave both T. gondii growth inhibition and DHFR inhibition IC50 values of 0.10 microM or less, thus indicating facile penetration of the cell membrane. Eleven of these inhibitors of both T. gondii growth and DHFR have selectivity ratios (IC50 rat liver divided by IC50 T. gondii) of 5 or greater for the parasite DHFR. The highest selectivity ratio of nearly 100 belongs to the 5-methyl-5-deaza compound whose 6-substituent is CH2CH2C6H3(OCH3)2-2,5. This compound is over 10(3)-fold more selective for T. gondii DHFR than bridge homologue piritrexim (selectivity ratio 0.088), a compound now in clinical trials. The candidate with CH2NHC6H3(CH3)2-2,5 in the 6-position gave the highest P. carinii DHFR selectivity ratio of 4.0, which is about 60-fold more selective than trimetrexate (0.071) and 80-fold more selective than piritrexim (0.048) toward this enzyme. The 10 best compounds with respect to potency and selectivity includes six compounds bearing 2,5-disubstituted phenyl groups in the side chain (with little, if any, difference in effects of methyl, methoxy, or ethoxy), two side chains bearing 1-naphthyl groups, and two with 5,6,7,8-tetrahydro-1-naphthyl groups. Bridge groups represented in the 10 choice compounds are CH2NH, CH2N(CH3), CH2CH2, and CH2S. The high levels of both potency and selectivity among these agents suggest that in vivo studies now underway may lead to agents that could replace trimetrexate and piritrexim in treatment of toxoplasmosis and P. carinii pneumonia.
Topics: Animals; Anti-Infective Agents; Folic Acid Antagonists; Opportunistic Infections; Pneumocystis; Pneumonia, Pneumocystis; Structure-Activity Relationship; Tetrahydrofolate Dehydrogenase; Toxoplasma; Toxoplasmosis; Trimetrexate
PubMed: 8632434
DOI: 10.1021/jm950760y -
Molecular Pharmacology Mar 1996We investigated the enzyme kinetic and antifolate inhibitory properties of human dihydrofolate reductase enzyme with mutations at position 22. Leu-22 was changed to...
We investigated the enzyme kinetic and antifolate inhibitory properties of human dihydrofolate reductase enzyme with mutations at position 22. Leu-22 was changed to isoleucine, methionine, phenylalanine, and tyrosine to generate the various mutant enzymes. The overall catalytic efficiency (kcat/Km) for methionine and phenylalanine mutants was reduced approximately 3-fold and >6-fold for isoleucine and tyrosine mutants. An arginine mutant (L22R) was also expressed but had a dramatically reduced catalytic potential (kcat>250-fold lower than wild-type) and therefore was not studied in detail. The Ki for antifolates, methotrexate, aminopterin, and trimetrexate are more dramatically affected (increased) than the Km for dihydrofolate, particularly for phenylalanine and tyrosine mutants. One remarkable feature is that the phenylalanine mutant is as potently inhibited by piritrexim as is the wild-type human enzyme, although the Ki values for methotrexate and aminopterin were increased 88- and 118-fold, respectively. This is likely related to different positioning of the methoxyphenyl side chain of piritrexim relative to the side chains of other compounds tested. A Chinese hamster cell line harboring the L22F mutant also demonstrated an increased sensitivity of piritrexim relative to antifolates.
Topics: Animals; Base Sequence; CHO Cells; Cells, Cultured; Cricetinae; Enzyme Inhibitors; Folic Acid Antagonists; Genetic Variation; Humans; Isoleucine; Kinetics; Leucine; Methotrexate; Molecular Sequence Data; Mutagenesis; Mutation; Structure-Activity Relationship; Tetrahydrofolate Dehydrogenase
PubMed: 8643082
DOI: No ID Found -
Journal of Medicinal Chemistry Feb 1996A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between... (Comparative Study)
Comparative Study
High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Anti-Infective Agents; Antineoplastic Agents; Brain Neoplasms; Candidiasis; Cell Division; Cell Line; Crystallography, X-Ray; Drug Design; Drug Resistance, Multiple; Enzyme Inhibitors; Folic Acid Antagonists; Humans; Lung Neoplasms; Magnetic Resonance Spectroscopy; Mass Spectrometry; Mice; Mice, Nude; Mice, SCID; Models, Molecular; Molecular Conformation; Molecular Structure; Molecular Weight; Pneumonia, Pneumocystis; Protein Structure, Secondary; Quinazolines; Structure-Activity Relationship; Toxoplasma; Tumor Cells, Cultured
PubMed: 8632413
DOI: 10.1021/jm9505122