Discovery of selective urokinase plasminogen activator (uPA) inhibitors as a potential treatment for multiple sclerosis.

We report here the design and synthesis of a novel series of benzylamines that are potent and selective inhibitors of uPA with promising oral availability in rat. Further evaluation of one representative (ZK824859) of the new structural class showed that this compound lowered clinical scores when dosed in either acute or chronic mouse EAE models, suggesting that uPA inhibitors of this type could be useful for the treatment of multiple sclerosis.

Mechanistic Modeling of the Pharmacodynamic and Pharmacokinetic Relationship of Tissue Factor Pathway Inhibitor-Neutralizing Antibody (BAY 1093884) in Cynomolgus Monkeys.

BAY 1093884 is a fully human monoclonal antibody against the tissue factor pathway inhibitor (TFPI) in development as prophylaxis in patients with hemophilia with or without inhibitors. In vitro, BAY 1093884 binds to human, mouse, and monkey TFPI. The objective of this study was to find a pharmacodynamic (PD) biomarker after administration of BAY 1093884 to normal monkeys. In monkey plasma, BAY 1093884 exhibited an IC50 (concentration that inhibits 50%) of 4.65 and 6.19 nM for free TFPI and diluted prothrombin time (dPT), respectively. The BAY 1093884 pharmacokinetic (PK) profile and its PD effects on dPT and free TFPI levels were assessed after intravenous and subcutaneous administration of BAY 1093884 (5 and 20 mg/kg) to female cynomolgus monkeys. Free TFPI concentrations in plasma decreased rapidly and increased to baseline in a dose-dependent manner. dPT clotting time was shortened and correlated with free TFPI levels and drug concentration in plasma, demonstrating the relationship between PD activities (dPT clotting time and free TFPI levels) and drug concentration. BAY 1093884 exhibited nonlinear PK, and a target-mediated drug disposition model was used to characterize the BAY 1093884 versus TFPI concentration-response relationship. We concluded that a mechanism-based PK/PD binding model could be useful for predicting human response to BAY 1093884. For the first-in-human study, measurement of free TFPI will be included as part of the dose-escalation design.

Noncovalent stabilization of the factor VIII A2 domain enhances efficacy in hemophilia A mouse vascular injury models.

An important negative regulator of factor VIIIa (FVIIIa) cofactor activity is A2 subunit dissociation. FVIII molecules with stabilized activity have been generated by elimination of charged residues at the A1-A2 and A2-A3 interfaces. These molecules exhibited reduced decay rates as part of the enzymatic factor Xa generation complex and retained their activities under thermal and chemical denaturing conditions. We describe here the potency and efficacy of 1 such stability variant, D519V/E665V, derived from B domain-deleted FVIII (BDD-FVIII). The major effect of A2 stabilization was on cofactor activity. D519V/E665V potency was increased twofold by the 2-stage chromogenic assay relative to BDD-FVIII. D519V/E665V demonstrated enhanced thrombin generation responses (fivefold by peak thrombin) relative to BDD-FVIII. In vivo consequences of enhanced cofactor activity of D519V/E665V included >fourfold increased maximal platelet-fibrin deposition after laser injury and twofold increased protection from bleeding in acute and prolonged vascular injury model in hemophilia A mice. These results demonstrate that noncovalent stabilization of the FVIII A2 subunit can prolong its cofactor activity, leading to differential enhancement in clot formation over protection from blood loss in hemophilia. The FVIII molecule described here is the first molecule with clear efficacy enhancement resulting from noncovalent stabilization of the A2 domain.

Hepatocyte clearance and pharmacokinetics of recombinant factor IX glycosylation variants.

Addition of N-linked glycosylation sites has been shown to increase serum half-life and decrease clearance for proteins such as recombinant erythropoietin (EPO). However, factor IX (FIX) variants with additional N-linked glycans ("HG" variants) that were expressed in HKB11 cells showed increased clearance in rat in vivo pharmacokinetic studies relative to FIX variants with no additional glycans. Variants with multiple additional glycans were the most rapidly cleared. A rat hepatocyte clearance assay was developed to measure intrinsic clearance of these FIX variants in vitro. The rank order of clearance of the variants was the same both in vivo and in the in vitro hepatocyte assay. In the in vitro assay, heparin, galactose, and asialo-orosomucoid inhibited clearance of a FIX HG variant by hepatocytes, and asialo-FIX was rapidly cleared, suggesting roles for the asialoglycoprotein receptor (ASGPR) and cell surface proteoglycans in FIX clearance. Thus the in vitro hepatocyte intrinsic clearance assay is both useful and predictive for identifying rapidly cleared recombinant proteins and for helping to identify receptors involved in clearance of proteins by the liver.

Identification of orally bioavailable, non-amidine inhibitors of Urokinase Plasminogen Activator (uPA).

In this Letter we report the synthesis and evaluation of a series of non-amidine inhibitors of Urokinase Plasminogen Activator (uPA). Starting from compound 1, a significant change provided compounds in which the amidine, binding in the S1 pocket, was replaced with a primary amine. Further modifications led to the identification of potent, selective, and orally bioavailable uPA inhibitors.

The association between elevated ankle systolic pressures and peripheral occlusive arterial disease in diabetic and nondiabetic subjects.

OBJECTIVE: The presence of a high ankle-brachial index (ABI) is related to stiff ankle arteries due to medial calcification. Recently, this condition has attracted new interest after reports of a worse cardiovascular prognosis, similar to a low ABI. We sought to compare risk factors contributing to a low (< or =0.90) and high (> or =1.40) ABI. Additionally, we hypothesized that in instances of high ABI, occlusive PAD may coexist. METHOD: This cross-sectional study was conducted at vascular laboratories in a university medical center. The subjects were 510 ambulatory patients (37% had diabetes) previously examined at our vascular laboratories and who responded positively to our invitation. We collected data on smoking, diabetes, hypertension, dyslipidemia, and cardiovascular disease history. The noninvasive assessment of lower limb arteries consisted of the measurement of ABI, toe-brachial index (TBI), and posterior tibial artery peak flow velocity (Pk-PT). A TBI >0.7 and a Pk-PT >10 cm/s were considered normal. RESULTS: High- and low-ABI were detected, respectively, in 2.1% and 57.8% of limbs. For a low ABI, age (odds ratio [OR], 1.29/10 y), pack-years (OR, 1.08/10 units), and hypertension (OR, 1.90) were independent significant (P < .001) factors. A strong association was found between diabetes and high ABI (OR, 16.0; P < .001). When ABI ranges were compared with TBI and Pk-PT results, those with ABI < or =0.90 and ABI > or =1.40 presented similar patterns of abnormalities. Pk-PT or TBI, or both, was abnormal in more than 80% of cases in both ABI < or =0.90 and > or =1.40 groups. The ABI vs TBI relationship appeared linear in nondiabetic patients, but had an inverted J-shape in diabetic patients, suggesting high ABI masked leg ischemia. CONCLUSIONS: Diabetes is the dominant risk factor for a high (> or =1.40) ABI. Occlusive PAD is highly prevalent in subjects with high ABI, and these subjects should be considered as PAD-equivalent.

Indolinone based phosphoinositide-dependent kinase-1 (PDK1) inhibitors. Part 2: optimization of BX-517.

Based on the lead compound BX-517, a series of C-4' substituted indolinones have been synthesized and evaluated for PDK1 inhibition. Modification at C-4' of the pyrrole afforded potent compounds (7b and 7d) with improved solubility and ADME properties. In this letter, we describe the synthesis, selectivity profile, and pharmacokinetic data of selected compounds.

Indolinone based phosphoinositide-dependent kinase-1 (PDK1) inhibitors. Part 1: design, synthesis and biological activity.

HTS screening identified 1 with micromolar inhibitory activity against PDK1. Optimization of 1 afforded 4i (BX-517) which has single-digit nanomolar activity against PDK1 and excellent selectivity against PKA.

Ethnic-specific prevalence of peripheral arterial disease in the United States.

BACKGROUND: Individuals diagnosed with peripheral arterial disease (PAD) are at increased risk for future functional limitations as well as cardiovascular morbidity and mortality. The aim of this study was to estimate the age-, gender-, and ethnic-specific burden of PAD in the United States for the year 2000. METHODS: Data were collected from seven community-based studies that assessed subjects for the presence of PAD using the ankle-brachial index (ABI). Using standardized weighting criteria, age-, gender-, and ethnic-specific prevalence rates were computed and then multiplied by the corresponding 2000 Census population totals to estimate the burden of PAD in the United States for that year. Evidence-based adjustments for studies which did not consider possible subclavian stenosis, prior revascularization for PAD, or both were employed. RESULTS: In 2000, it is conservatively estimated that at least 6.8 million (5.8%) individuals aged 40 years or older had PAD based on an ABI of less than 0.9 or previous revascularization for PAD, and that that there are an additional 1.7 million Americans with PAD but "normal" ABIs. Including this group gives a total of 8.5 million (7.2%) individuals with PAD. CONCLUSIONS: Roughly one in 16 individuals residing in the United States in 2000 who were aged 40 years and older had PAD. Clinicians are encouraged to screen for the presence of PAD using the ABI.

1-(1,3-Benzodioxol-5-ylmethyl)-3-[4-(1H-imidazol-1-yl)phenoxy]-piperidine analogs as potent and selective inhibitors of nitric oxide formation.

A new series of 1-(1,3-benzodioxol-5-ylmethyl)-3-[4-(1H-Imidazol-1-yl)phenoxy]-piperidine analogs were designed and identified as potent and selective inhibitors of NO formation based both on the crystal structure of a murine iNOS Delta114 monomer domain/ inhibitor complex and inhibition of the NO formation in human A172 cell assays. Compound 12S showed high potency and high iNOS selectivity versus nNOS and eNOS.

Substituted thiophene-anthranilamides as potent inhibitors of human factor Xa.

A series of thiophene-containing non-amidine factor Xa inhibitors is described. Simple methyl-substituted thiophene analogs were relatively weak inhibitors. However, introduction of hydrophilic substituents at C-4 or C-5 of the thiophene afforded inhibitors with low nanomolar potency. Optimization of the thiophene substituent at C-4 afforded subnanomolar inhibitors with improved in vitro anticoagulant activity. Incorporating basic amine substituents on the thiophene increased hydrophilicity and improved anticoagulant activity. The pharmacokinetic profile of one inhibitor was evaluated in dogs, and the X-ray crystal structure of this compound bound to factor Xa provides insight into the observed SAR for binding to factor Xa.

Ethnicity and peripheral arterial disease: the San Diego Population Study.

BACKGROUND: Previous studies have indicated higher rates of peripheral arterial disease (PAD) in blacks than in non-Hispanic whites (NHWs), with limited information available for Hispanics and Asians. The reason for the PAD excess in blacks is unclear. METHODS AND RESULTS: Ethnic-specific PAD prevalence rates were determined in a randomly selected defined population that included 4 ethnic groups; NHWs, blacks, Hispanics, and Asians. A total of 2343 participants aged 29 to 91 years were evaluated. There were 104 cases of PAD (4.4%). In weighted logistic models with NHWs as the reference group and containing demographic factors only, blacks had a higher PAD prevalence than NHWs (OR=2.30, P<0.024), whereas PAD rates in Hispanics and Asians, although somewhat lower, were not significantly different from NHWs. Blacks had significantly more diabetes and hypertension than NHWs and a significantly higher body mass index. Inclusion of these variables and other PAD risk factors in the model did not change the effect size for black ethnicity (OR=2.34, P=0.048). A model containing interaction terms for black ethnicity and each of the other risk factors revealed no significant interaction terms, which indicates no evidence that blacks were more "susceptible" than NHWs to cardiovascular disease risk factors. CONCLUSIONS: Black ethnicity was a strong and independent risk factor for PAD, which was not explained by higher levels of diabetes, hypertension, and body mass index. There was no evidence of a greater susceptibility of blacks to cardiovascular disease risk factors as a reason for their higher PAD prevalence. Thus, the excess risk of PAD in blacks remains unexplained and requires further study.

Relationships between symptoms and venous disease: the San Diego population study.

BACKGROUND: The associations between symptoms and venous disease of the lower extremities are poorly characterized. METHODS: We conducted a cross-sectional study to evaluate relationships between symptoms associated with venous disease and prevalent disease in 2408 men and women aged 29 to 91 years who were employees, retirees, or spouses at a large state university. Index participants were randomly selected within strata by age, sex, and ethnicity. A structured interview assessed the prevalence of aching, itching, heaviness, tired legs, cramping, swelling, and nighttime restless legs. A comprehensive standardized examination determined the prevalence of visible disease (normal, telangiectasias, varicose veins, and trophic changes) and functional disease (normal, superficial, and deep disease). We related symptoms to disease with attention to modification by sex, ethnicity, and age. RESULTS: Aching, itching, heaviness, tired legs, cramping, and swelling were related to both superficial and deep functional disease. The same symptoms were related to varicose veins and trophic changes. Swelling and heaviness were related to telangiectatic disease. Except for restless legs and trophic changes, the prevalence of symptoms across each category was greater in women than men. Aching was the most common symptom but was relatively nonspecific. Swelling was the most specific marker for prevalent visible and functional disease. Heaviness and itching also helped to distinguish prevalent disease. CONCLUSIONS: Venous symptoms were more prevalent in study participants with both visible and functional disease and in women. Swelling was the most specific predictor; heaviness, itching, and aching also helped to distinguish cases.

Differential inhibition of inducible T cell cytokine secretion by potent iron chelators.

Effector functions and proliferation of T helper (Th) cells are influenced by cytokines in the environment. Th1 cells respond to a synergistic effect of interleukin-12 (IL-12) and interleukin-18 (IL-18) to secrete interferon-gamma (IFN-gamma). In contrast, Th2 cells respond to interleukin-4 (IL-4) to secrete IL-4, interleukin-13 (IL-13), interleukin-5 (IL-5), and interleukin-10 (IL-10). The authors were interested in identifying nonpeptide inhibitors of the Th1 response selective for the IL-12/IL-18-mediated secretion of IFN-gamma while leaving the IL-4-mediated Th2 cytokine secretion relatively intact. The authors established a screening protocol using human peripheral blood mononuclear cells (PBMCs) and identified the hydrazino anthranilate compound 1 as a potent inhibitor of IL-12/IL-18-mediated IFN-gamma secretion from CD3(+) cells with an IC(50) around 200 nM. The inhibitor was specific because it had virtually no effect on IL-4-mediated IL-13 release from the same population of cells. Further work established that compound 1 was a potent intracellular iron chelator that inhibited both IL-12/IL-18- and IL-4-mediated T cell proliferation. Iron chelation affects multiple cellular pathways in T cells. Thus, the IL-12/IL-18-mediated proliferation and IFN-gamma secretion are very sensitive to intracellular iron concentration. However, the IL-4-mediated IL-13 secretion does not correlate with proliferation and is partially resistant to potent iron chelation.

Anti-tumor efficacy of the nucleoside analog 1-(2-deoxy-2-fluoro-4-thio-beta-D-arabinofuranosyl) cytosine (4'-thio-FAC) in human pancreatic and ovarian tumor xenograft models.

1-(2-deoxy-2-fluoro-4-thio-beta-D-arabinofuranosyl) cytosine (4'-thio-FAC) is a deoxycytidine analog that has been shown previously to have impressive anti-proliferative and cytotoxic effects in vitro and in vivo toward colorectal and gastric tumors. In our present studies, the pharmacokinetic behavior in nude mice and the effectiveness of 4'-thio-FAC against human pancreatic and ovarian tumor growth were assessed in comparison with standard chemotherapeutic agents. Potent in vitro anti-proliferative effects were observed against pancreatic (Capan-1, MIA-PaCa-2, BxPC-3) and ovarian (SK-OV-3, OVCAR-3, ES-2) cancer cell lines with IC(50) of 0.01-0.2 microM. In vivo anti-tumor activity was evaluated in nude mice bearing subcutaneously (s.c.) implanted human pancreatic tumor xenografts or intraperitoneally (i.p.) disseminated human ovarian xenografted tumors. Oral daily administration of 4'-thio-FAC for 8-10 days significantly inhibited the growth of gemcitabine-resistant BxPC-3 pancreatic tumors and induced regression of gemcitabine-refractory Capan-1 tumors. 4'-Thio-FAC was also a highly effective inhibitor of ovarian peritoneal carcinomatosis. In the SK-OV-3 and ES-2 ovarian cancer models, 4'-thio-FAC prolonged survival to a greater extent than that observed with gemcitabine. Furthermore, the superiority of 4'-thio-FAC to carboplatin and paclitaxel was demonstrated in the ES-2 clear cell ovarian carcinoma model. Studies provide evidence that 4'-thio-FAC is a promising new alternative to gemcitabine and other chemotherapeutic drugs in the treatment of a variety of tumor indications, including pancreatic and ovarian carcinoma.

Measurements of drug-protein binding by using immobilized human serum albumin liquid chromatography-mass spectrometry.

An HPLC/MS based method was used for fast and convenient determination of drug plasma-protein interactions in early drug discovery screening by employing a human serum albumin affinity column. Results from this methodology were compared with data from ultrafiltration or dialysis methods, and good agreement was observed. A compound not suitable for ultrafiltration due to the very high non-specific binding to artificial membrane of ultrafiltration device was also successfully analyzed by this method, and the protein binding determined by this chromatography method was very similar to data obtained by dialysis technique employing biological membranes. The immobilized HSA column LC/MS method also proved to be more reproducible and precise compared to ultrafiltration method in drug protein binding measurements.

Design, synthesis, and activity of a novel series of factor Xa inhibitors: optimization of arylamidine groups.

A novel series of diaryloxypyridines have been designed as selective nanomolar factor Xa (fXa) inhibitors for use as anticoagulants. In this paper, we describe our efforts to identify an additional interaction and a replacement for the distal amidine group that binds in the S3/S4 pocket of fXa. Introduction of a hydroxyl group para to the proximal amidine group increases the potency vs fXa by 1-2 orders of magnitude, which is the result of a hydrogen bond to Ser195 of the catalytic triad. A methyl imidazoline and a dimethylamide are good alternatives for the second amidine. These substitutions have increased the selectivity vs the related serine proteases trypsin and thrombin. The synthesis, in vitro activity, and hypothetical modes of binding to fXa based on trypsin crystallographic data are outlined.

Design, synthesis, and biological activity of novel factor Xa inhibitors: 4-aryloxy substituents of 2,6-diphenoxypyridines.

A novel series of triaryloxypyridines have been designed to inhibit factor Xa, a serine protease strategically located in the coagulation cascade. Inhibitor 5e has a K(I) against factor Xa of 0.12nM and is greater than 8000- and 2000-fold selective over two related serine proteases, thrombin and trypsin, respectively. The 4-position of the central pyridine has been identified as a site that tolerates various substitutions without deleterious effects on potency and selectivity. This suggests that the 4-position of the pyridine ring is an ideal site for chemical modifications to identify inhibitors with improved pharmacokinetic characteristics. This investigation has resulted in inhibitor 5d, which has an oral availability of 6% in dogs. The synthesis, in vitro activity, and in vivo profile of this class of inhibitors is outlined.