The Fluorocycline TP-271 Is Efficacious in Models of Aerosolized Francisella tularensis SCHU S4 Infection in BALB/c Mice and Cynomolgus Macaques.

TP-271 is a novel, fully synthetic fluorocycline in development for complicated bacterial respiratory infections. TP-271 was active in vitro against a panel of 29 Francisella tularensis isolates, showing MICs against 50% and 90% of isolates of 0.25 and 0.5 µg/ml, respectively. In a mouse model of inhalational tularemia, animals were exposed by aerosol to 91 to 283 50% lethal doses (LD50)/mouse of F. tularensis SCHU S4. Following 21 days of once-daily intraperitoneal dosing with TP-271 at 3, 6, 12, and 18 mg/kg of body weight/day, initiating at 24 h postchallenge, survival was 80%, 100%, 100%, and 100%, respectively. When treatment was initiated at 72 h postchallenge, survival was 89%, 100%, 100%, and 100% in the 3-, 6-, 12-, and 18-mg/kg/day TP-271 groups, respectively. No mice treated with the vehicle control survived. Surviving mice treated with TP-271 showed little to no relapse during 14 days posttreatment. In a nonhuman primate model of inhalational tularemia, cynomolgus macaques received an average aerosol exposure of 1,144 CFU of F. tularensis SCHU S4. Once-daily intravenous infusion with 1 or 3 mg/kg TP-271, or vehicle control, for 21 days was initiated within 6 h of confirmed fever. All animals treated with TP-271 survived to the end of the study, with no relapse during 14 days after the last treatment, whereas no vehicle control-treated animals survived. The protection and low relapse afforded by TP-271 treatment in these studies support continued investigation of TP-271 for use in the event of aerosolized exposure to F. tularensis.

Potent, orally bioavailable delta opioid receptor agonists for the treatment of pain: discovery of N,N-diethyl-4-(5-hydroxyspiro[chromene-2,4'-piperidine]-4-yl)benzamide (ADL5859).

Selective delta opioid receptor agonists are promising potential therapeutic agents for the treatment of various types of pain conditions. A spirocyclic derivative was identified as a promising hit through screening. Subsequent lead optimization identified compound 20 (ADL5859) as a potent, selective, and orally bioavailable delta agonist. Compound 20 was selected as a clinical candidate for the treatment of pain.

Potent, exceptionally selective, orally bioavailable inhibitors of TNF-alpha Converting Enzyme (TACE): novel 2-substituted-1H-benzo[d]imidazol-1-yl)methyl)benzamide P1' substituents.

Novel ((2-substituted-1H-benzo[d]imidazol-1-yl)methyl)benzamides were found to be excellent P1' substituents in conjunction with unique constrained beta-amino hydroxamic acid scaffolds for the discovery of potent selective inhibitors of TNF-alpha Converting Enzyme (TACE). Optimized examples proved potent for TACE, exceptionally selective over a wide panel of MMP and ADAM proteases, potent in the suppression of LPS-induced TNF-alpha in human whole blood and orally bioavailable.

Alpha,Beta-cyclic-beta-benzamido hydroxamic acids: Novel oxaspiro[4.4]nonane templates for the discovery of potent, selective, orally bioavailable inhibitors of tumor necrosis factor-alpha converting enzyme (TACE).

Two novel oxaspiro[4.4]nonane beta-benzamido hydroxamic scaffolds have been synthesized in enantio- and diasteriomerically pure form. These templates proved to be exceptional platforms that have led to the discovery of potent inhibitors of TACE that are active in a cellular assay measuring suppression of LPS-induced TNF-alpha. Furthermore, these inhibitors are selective against related MMPs, demonstrate permeability in a Caco-2 assay, and display good oral bioavailability.

Potent, selective, orally bioavailable inhibitors of tumor necrosis factor-alpha converting enzyme (TACE): discovery of indole, benzofuran, imidazopyridine and pyrazolopyridine P1' substituents.

Potent and selective inhibitors of tumor necrosis factor-alpha converting enzyme (TACE) were discovered with several new heterocyclic P1' groups in conjunction with cyclic beta-amino hydroxamic acid scaffolds. Among them, the pyrazolopyridine provided the best overall profile when combined with tetrahydropyran beta-amino hydroxamic acid scaffold. Specifically, inhibitor 49 showed IC(50) value of 1 nM against porcine TACE and 170 nM in the suppression of LPS-induced TNF-alpha of human whole blood. Compound 49 also displayed excellent selectivity over a wide panel of MMPs as well as excellent oral bioavailability (F%>90%) in rat n-in-1 PK studies.

N-in-1 dosing pharmacokinetics in drug discovery: experience, theoretical and practical considerations.

N-in-1 (or cassette) dosing pharmacokinetics (PK) has been used in drug discovery for rapid assessment of PK properties of new chemical entities. However, because of potential for drug-drug interactions this procedure is still controversial. This study was to retrospectively evaluate the N-in-1 dosing approach in drug discovery with an emphasis on the potential for drug-drug interactions. The systemic clearance, volume of distribution, oral bioavailability, and renal excretion of the 31 lead compounds in rats, dogs or chimpanzees were significantly correlated between the N-in-1 dosing and discrete studies with r values of 0.69, 0.91, 0.53, and 0.83 (p < 0.005 for all), respectively. PK parameters for 11 quality control compounds which were involved in 194 N-in-1 studies for screening approximately 1000 compounds had coefficient of variations of less than 70%. The intrinsic microsomal clearances generated from the N-in-1 and discrete incubations were nearly identical (r = 0.97, p < 0.0001). The intrinsic clearances of quality control compound from the N-in-1 incubations were consistent with its discrete CL(int) estimate (cv: 5.4%). Therefore, N-in-1 dosing is a useful approach in drug discovery to quickly obtain initial PK estimates. Potential drug-drug interactions that result in confounding PK estimates do not occur as frequently as expected.

Alpha,beta-cyclic-beta-benzamido hydroxamic acids: novel templates for the design, synthesis, and evaluation of selective inhibitors of TNF-alpha converting enzyme (TACE).

Selective inhibitors of TNF-alpha Converting Enzyme (TACE) based on (1R,2S)-cyclopentyl, (3S,4S)-pyrrolidinyl, and (3R,4S)-tetrahydrofuranyl beta-benzamido hydroxamic acids have been synthesized and evaluated. This study has led to the discovery of novel inhibitors whose profiles include activity against TACE in an enzyme assay, potency in the suppression of LPS-stimulated TNF-alpha in human whole blood, selectivity against a panel of MMPs and oral bioavailability.

Discovery of beta-benzamido hydroxamic acids as potent, selective, and orally bioavailable TACE inhibitors.

Beta-benzamido hydroxamic acids were discovered as potent TACE inhibitors. A computer model was constructed to help understanding the binding activities and guiding SAR study. SAR optimization led to the discovery of compound 30 which met all in vitro and in vivo criteria for the program and was selected for further evaluation.

Species-specific, P450- and sulfotransferase-mediated novel ring contraction of a naphthyridine-N-oxide compound in cynomolgus monkey.

BMS-A78277 (1) is a 5,10-dihydrobenzo[beta][1,8]naphthyridine-N-oxide compound that resides in a class of novel non-nucleoside reverse transcriptase inhibitors (NNRTIs), displaying improved activity against clinically relevant mutants of HIV-1 and possessing pharmacokinetic profiles amenable to once-daily dosing. In the course of investigating the nonclinical metabolism of 1, a circulating metabolite specific to the cynomolgus monkey was identified and subsequently characterized as the carboxyindole metabolite 2. The present investigation describes the biotransformation of this NNRTI in cynomolgus monkey, one which results in a net ring contraction of 1. The use of mass spectrometry and high field NMR analysis aided in the structural characterization of metabolite 2, the source of which originated from the urine and bile of cynomolgus monkeys receiving oral doses of 1. Preparation of a synthetic standard of 2 not only provided ultimate structural confirmation but also afforded ample material for biological testing. The metabolism of 1 was investigated in monkey hepatocytes and hepatic subcellular fractions. While microsomes were incapable of generating metabolite 2, incubation of 1 in monkey S9 fractions as well as hepatocytes resulted in measurable levels of the carboxyindole metabolite. Consequently, incubation of 1 in monkey hepatocytes, which were suspended in media containing (18)O-labeled water, resulted in the incorporation of (18)O into the carboxyindole metabolite, 2. These data implicate a mechanism involving the bioactivation of 1 to an electrophilic intermediate that upon hydrolysis undergoes a concerted ring contraction, resulting in the formation of 2. Previously confined to discussions regarding the metabolism of natural products and select aliphatic heterocycles, the present investigation extends the discussion of metabolism-mediated ring contraction to aromatics such as the present naphthyridine compound, 1.

Pharmacokinetics and pharmacodynamics of DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)), a potent and selective inhibitor of tumor necrosis factor alpha-converting enzyme in rodents, dogs, chimpanzees, and humans.

DPC 333 ((2R)-2-((3R)-3-amino-3{4-[2-methyl-4-quinolinyl) methoxy] phenyl}-2-oxopyrrolidinyl)-N-hydroxy-4-methylpentanamide)) is a potent and selective inhibitor of tumor necrosis factor (TNF)-alpha-converting enzyme (TACE). It significantly inhibits lipopolysaccharide-induced soluble TNF-alpha production in blood from rodents, chimpanzee, and human, with IC(50) values ranging from 17 to 100 nM. In rodent models of endotoxemia, DPC 333 inhibited the production of TNF-alpha in a dose-dependent manner, with an oral ED(50) ranging from 1.1 to 6.1 mg/kg. Oral dosing of DPC 333 at 5.5 mg/kg daily for 2 weeks in a rat collagen antibody-induced arthritis model suppressed the maximal response by approximately 50%. DPC 333 was distributed widely to tissues including the synovium, the site of action for antiarthritic drugs. Pharmacokinetic and pharmacodynamic studies in chimpanzee revealed a systemic clearance of 0.4 l/h/kg, a V(ss) of 0.6 l/kg, an oral bioavailability of 17%, and an ex vivo IC(50) for the suppression of TNF-alpha production of 55 nM (n = 1). In a phase I clinical trial with male volunteers after single escalating doses of oral DPC 333, the terminal half-life was between 3 and 6 h and the ex vivo IC(50) for suppressing TNF-alpha production was 113 nM. Measurement of the suppression of TNF-alpha production ex vivo may serve as a good biomarker in evaluating the therapeutic efficacy of TACE inhibitors. Overall, the pharmacological profiles of DPC 333 support the notion that suppression of TNF-alpha with TACE inhibitors like DPC 333 may provide a novel approach in the treatment of various inflammatory diseases including rheumatoid arthritis, via control of excessive TNF-alpha production.

CC chemokine receptor-3 (CCR3) antagonists: improving the selectivity of DPC168 by reducing central ring lipophilicity.

DPC168, a benzylpiperidine-substituted aryl urea CCR3 antagonist evaluated in clinical trials, was a relatively potent inhibitor of the 2D6 isoform of cytochrome P-450 (CYP2D6). Replacement of the cyclohexyl central ring with saturated heterocycles provided potent CCR3 antagonists with improved selectivity against CYP2D6. The favorable preclinical profile of DPC168 was maintained in an acetylpiperidine derivative, BMS-570520.

A new 4-(2-methylquinolin-4-ylmethyl)phenyl P1' group for the beta-amino hydroxamic acid derived TACE inhibitors.

A new P1' group for TACE inhibitors was identified by eliminating the oxygen atom in the linker of the original 4-(2-methylquinolin-4-ylmethoxy)phenyl P1' group. Incorporation of this 4-(2-methylquinolin-4-ylmethyl)phenyl group onto different beta-aminohydroxamic acid cores provided compound 18, which demonstrated potent porcine TACE (p-TACE) and human whole blood activity, excellent PK properties, and good selectivity against a variety of MMPs.

The chimpanzee (Pan troglodytes) as a pharmacokinetic model for selection of drug candidates: model characterization and application.

The chimpanzee (CHP) was evaluated as a pharmacokinetic model for humans (HUMs) using propranolol, verapamil, theophylline, and 12 proprietary compounds. Species differences were observed in the systemic clearance of theophylline (approximately 5-fold higher in CHPs), a low clearance compound, and the bioavailability of propranolol and verapamil (lower in CHPs), both high clearance compounds. The systemic clearance of propranolol (approximately 1.53 l/h/kg) suggested that the hepatic blood flow in CHPs is comparable to that in humans. No substantial differences were observed in the in vitro protein binding. A preliminary attempt was made to characterize cytochrome P450 (P450) activities in CHP and HUM liver microsomes. Testosterone 6beta-hydroxylation and tolbutamide methylhydroxylation activities were comparable in CHP and HUM liver microsomes. In contrast, dextromethorphan O-demethylation and phenacetin O-deethylation activities were approximately 10-fold higher (per mg protein) in CHP liver microsomes. Intrinsic clearance estimates in CHP liver microsomes were higher for propranolol (approximately 10-fold) and theophylline (approximately 5-fold) and similar for verapamil. Of the 12 proprietary compounds, 3 had oral clearances that differed in the two species by more than 3-fold, an acceptable range for biological variability. Most of the observed differences are consistent with species differences in P450 enzyme activity. Oral clearances of proprietary compounds in HUMs were significantly correlated to those from CHPs (r = 0.68; p = 0.015), but not to estimates from rat, dog, and monkey. In summary, the chimpanzee serves as a valuable surrogate model for human pharmacokinetics, especially when species differences in P450 enzyme activity are considered.

Sultam hydroxamates as novel matrix metalloproteinase inhibitors.

In this communication we describe the design, synthesis, and evaluation of novel sultam hydroxamates 4 as MMP-2, -9, and -13 inhibitors. Compound 26 was found to be an active inhibitor (MMP-2 IC(50) = 1 nM) with 1000-fold selectivity over MMP-1 and good oral bioavailability (F = 43%) in mouse. An X-ray crystal structure of 26 in MMP-13 confirms the key hydrogen bonds and prime side binding in the active site.

Rational design, synthesis and structure-activity relationships of a cyclic succinate series of TNF-alpha converting enzyme inhibitors. Part 2: lead optimization.

Modifications of the lead TACE inhibitor 1 (N-hydroxy-trans-2-[[4-(4-quinolinyloxymethyl)anilinyl]carbonyl]-1-cyclohexanecarboxamide) at the cyclohexyl ring and the quinoline moiety led to the identification of a series of piperidine containing TACE inhibitors with potent activity in the inhibition of TNF-alpha release in the whole blood assay (WBA). The most potent analogue IM491 [N-hydroxy-(5S,6S)-1-methyl-6-[[4-(2-methyl-4-quinolinylmethoxy)anilinyl]carbonyl]-5-piperidinecarboxamide] exhibited an IC(50) value of 20 nM in WBA with excellent selectivity over MMP-1, -2 and -9 and is orally bioavailable with an F value of 43% in beagle dogs.

Design, synthesis, and evaluation of benzothiadiazepine hydroxamates as selective tumor necrosis factor-alpha converting enzyme inhibitors.

Elevated levels of tumor necrosis factor-alpha (TNF-alpha) have been associated with several inflammatory diseases, and therefore, strategies for its suppression have become important targets in drug discovery. Our efforts to suppress TNF-alpha have centered on the inhibition of TNF-alpha converting enzyme (TACE) through the use of hydroxamate inhibitors. Starting from broad-spectrum matrix metalloproteinase (MMP) inhibitors, we have designed and synthesized novel benzothiadiazepines as potent and selective TACE inhibitors. The benzothiadiazepines were synthesized with variation in P1 and P1' in order to effect potency and selectivity. The inhibitors were evaluated versus porcine TACE (pTACE), and the initial selectivity was assessed with counterscreens of MMP-1, -2, and -9. Several potent and selective inhibitors were discovered with compound 41 being the most active against pTACE (K(i) = 5 nM) while still maintaining good selectivity versus the MMP's (at least 75-fold). Most compounds were assessed in the human peripheral blood mononuclear cell assay (PBMC) and the human whole blood assay (WBA) to determine their ability to suppress TNF-alpha. Compound 32 was the most potent compound in the PBMC assay (IC(50) = 0.35 microM), while compound 62 was the most active in the WBA (IC(50) = 1.4 microM).

Development of a dog microdialysis model for determining synovial fluid pharmacokinetics of anti-arthritis compounds exemplified by methotrexate.

PURPOSE: The purpose of this study was to develop and validate an animal model of drug disposition in synovial fluid (SF) by comparing microdialysis with arthrocentesis using the anti-arthritic drug methotrexate (MTX). METHODS: Microdialysis probes were calibrated in vitro with the no net flux method using dog synovial fluid. The probes were implanted surgically into the stifle joint space of four dogs and were dialyzed overnight using a portable microinfusion pump. The membrane integrity of the probes was monitored by retrodialysis using an internal standard. After an intravenous bolus of 2.5 mg/kg of MTX, unbound concentrations in synovial fluid, as well as total plasma concentrations, were measured by liquid chromatography tandam mass spectrometer (LC/MS/MS) in samples collected from 0 to 48 h postdose. RESULTS: The probe membrane remained intact at least 48 h after implantation. The mean probe recovery and unbound fraction of MTX in SF were 46.8% and 44.8%, respectively. The unbound fraction of MTX was 44% in synovial fluid. MTX penetrated into the joint space rapidly, with maximal concentrations of 6.6 microM reached at approximately 1 h postdose. The unbound MTX area under the curve in SF was approximately 40% of the total area under the curve in plasma. These data agree well with the previous data obtained for MTX using arthrocentesis. CONCLUSION: In contrast with arthrocentesis, microdialysis enables the collection of multiple serial SF samples from individual animals with minimal trauma and potential blood contamination. This animal model should prove valuable for studying the disposition of new antiarthritis compounds or biomarkers in SF.

Potent and selective aggrecanase inhibitors containing cyclic P1 substituents.

Anti-succinate hydroxamates with cyclic P1 motifs were synthesized as aggrecanase inhibitors. The N-methanesulfonyl piperidine 23 and the N-trifluoroacetyl azetidine 26 were the most potent aggrecanase inhibitors both having an IC(50)=3nM while maintaining >100-fold selectivity over MMP-1, -2, and -9. The cyclic moieties were also capable of altering in vivo metabolism, hence delivering low clearance compounds in both rat and dog studies as shown for compound 14.

Discovery of gamma-lactam hydroxamic acids as selective inhibitors of tumor necrosis factor alpha converting enzyme: design, synthesis, and structure-activity relationships.

New gamma-lactam TACE inhibitors were designed from known MMP inhibitors. A homology model of TACE was built and examined to identify the S1' site as the key area for TACE selectivity over MMPs. Rational exploration of the P1'-S1' interactions resulted in the discovery of the 3,5-disubstituted benzyl ether as a TACE-selective P1' group. Further optimization led to the discovery of IK682 as a selective and orally bioavailable TACE inhibitor.

Interaction of ritonavir on tissue distribution of a [(14)c]L-valinamide, a potent human immunodeficiency virus-1 protease inhibitor, in rats using quantitative whole-body autoradiography.

N-[(3-fluorophenyl)methyl]glycyl-N-[3-[((3-aminophenyl)sulfonyl)- 2-(aminophenyl)amino]-(1S,2S)-2-hydroxy-1-(phenylmethyl)propyl]- 3-methyl-L-valinamide (DPC 681, DPC(1)) on oral coadministration with ritonavir (RTV) in rats caused a significant increase in systemic exposure to DPC. Following a single oral dose of [(14)C]DPC with and without RTV pretreatment in rats, and subsequent analysis of whole-body sections, prepared at 1 and 7 or 8 h postdose, using whole-body autoradiography showed an increase in radioactivity in tissues (e.g., brain, and testes) upon coadministration. The distribution of radioactivity in the brain parenchyma and ventricles was different, such that the concentration of radioactivity was greater in cerebrospinal fluid (CSF) than in central nervous system. Thus, the use of CSF concentration of the total radioactivity as a surrogate for brain penetration would result in an overestimation. DPC was determined to be metabolized prominently by rCYP3A4. The increased tissue exposure to DPC in rats could largely be attributed to inhibition of CYP3A1/2 by RTV. DPC was also a good substrate for P-glycoprotein (Pgp), with K(m) of 4 microM and V(max) of 13 pmol/min. The Pgp-mediated transport of DPC across Caco-2 cells was readily saturated at >or=10 microM and was inhibited significantly by RTV at 5 to 10 microM. The data above and the reported RTV concentrations suggested that both the Pgp and CYP3A4 inhibition by RTV may play a significant role in enhancing the systemic and tissue exposure to DPC in humans.