Odanacatib is a potent, selective, and neutral cathepsin K inhibitor which was developed to address the metabolic liabilities of the Cat K inhibitor L-873724. Substituting P1 and modifying the P2 ...side chain led to a metabolically robust inhibitor with a long half-life in preclinical species. Odanacatib was more selective in whole cell assays than the published Cat K inhibitors balicatib and relacatib. Evaluation in dermal fibroblast culture showed minimal intracellular collagen accumulation relative to less selective Cat K inhibitors.
Cathepsin K (Cat K) degrades bone type I collagen and is a target for the pharmacological treatment of osteoporosis. Further roles for Cat K have been recently described, some of which are supported ...by the use of purportedly selective Cat K inhibitors in human and rodent cell-based assays. Twelve commercial and non-commercial Cat K inhibitors were profiled against a panel of purified human, rat, and mouse cysteine cathepsins and in two cell-based enzyme occupancy assays for activity against Cat K, B, and L. Ten inhibitors, including the carbohydrazide Cat K inhibitor II (Boc-Phe-Leu-NHNH-CO-NHNH-Leu-Z), the non-covalent K4b, and the epoxide NC-2300, have either little Cat K selectivity, or appear poorly cell penetrant. The amino-acetonitrile-containing inhibitors L-873724 and odanacatib show greater than 100-fold human Cat K enzyme selectivity and have similar IC50 values against each cathepsin in cell-based and enzyme assays. The basic inhibitor balicatib has greater cellular potencies than expected on the basis of purified enzyme assays. The accumulation of 14C-balicatib in fibroblasts is blocked by prior treatment of the cells with NH4Cl, consistent with balicatib having lysosomotropic properties. These results support the use of L-873724 and odanacatib as tools to identify novel roles for Cat K using human cell-based systems, but suggest using caution in the interpretation of studies employing the other compounds.
Cathepsin K is a lysosomal cysteine protease that is a pharmacological target for the treatment of osteoporosis. Previous
studies showed that basic, lipophilic cathepsin K inhibitors are ...lysosomotropic and have greater activities in cell-based
assays against cathepsin K, as well as the physiologically important lysosomal cysteine cathepsins B, L, and S, than expected
based on their potencies against these isolated enzymes. Long-term administration of the basic cathepsin K inhibitors N -(1-(((cyanomethyl)amino)carbonyl)cyclohexyl)-4-(2-(4-methyl-piperazin-1-yl)-1,3-thiazol-4-yl)benzamide (L-006235) and balicatib
to rats at a supratherapeutic dose of 500 mg/kg/day for 4 weeks resulted in increased tissue protein levels of cathepsin B
and L but had no effect on cathepsin B and L message. This is attributed to the inhibitor engagement of these off-target enzymes
and their stabilization to proteolytic degradation. No such increase in these tissue cathepsins was detected at the same dose
of N -(cyanomethyl)- N 2 -{(1 S )-2,2,2-trifluoro-1-4'-methylsulfonyl)biphenyl-4-ylethyl}- l -leucinamide (L-873724), a potent nonbasic cathepsin K inhibitor with a similar off-target profile, although all three inhibitors
provided similar plasma exposures. Using an activity-based probe, 125 I-BIL-DMK, in vivo inhibition of cathepsins B, L, and S was detected in tissues of mice given a single oral dose of L-006235
and balicatib, but not in mice given L-873724. In each case, similar tissue levels were achieved by all three compounds, thereby
demonstrating the in vivo cathepsin selectivity of L-873724. In conclusion, basic cathepsin K inhibitors demonstrate increased
off-target cysteine cathepsin activities than their nonbasic analogs and potentially have a greater risk of adverse effects
associated with inhibition of these cathepsins.
Growing evidences indicate that proteases are implicated in adipogenesis and in the onset of obesity. We previously reported that the cysteine protease cathepsin K (ctsk) is overexpressed in the ...white adipose tissue (WAT) of obese individuals. We herein characterized the WAT and the metabolic phenotype of ctsk deficient animals (ctsk-/-). When the growth rate of ctsk-/- was compared to that of the wild type animals (WT), we could establish a time window (5-8 weeks of age) within which ctsk-/-display significantly lower body weight and WAT size as compared to WT. Such a difference was not observable in older mice. Upon treatment with high fat diet (HFD) for 12 weeks ctsk-/- gained significantly less weight than WT and showed reduced brown adipose tissue, liver mass and a lower percentage of body fat. Plasma triglycerides, cholesterol and leptin were significantly lower in HFD-fed-ctsk-/- as compared to HFD-fed WT animals. Adipocyte lipolysis rates were increased in both young and HFD-fed-ctsk-/-, as compared to WT. Carnitine palmitoyl transferase-1 activity, was higher in mitochondria isolated from the WAT of HFD treated ctsk-/- as compared to WT. Together, these data indicate that ctsk ablation in mice results in reduced body fat content under conditions requiring a rapid accumulation of fat stores. This observation could be partly explained by an increased release and/or utilization of FFA and by an augmented ratio of lipolysis/lipogenesis. These results also demonstrate that under a HFD, ctsk deficiency confers a partial resistance to the development of dyslipidemia.
The SAR from our peptide libraries was exploited to design a series of potent deoxybenzoin PTP-1B inhibitors. The introduction of an ortho bromo substituent next to the difluoromethylphosphonate ...warhead gave up to 20-fold increase in potency compared to the desbromo analogues. In addition, these compounds were orally bioavailable and active in the animal models of non-insulin dependent diabetes mellitus (NIDDM).
Summary Background Post-thrombotic syndrome (PTS) is a common and burdensome complication of deep venous thrombosis (DVT). Previous trials suggesting benefit of elastic compression stockings (ECS) to ...prevent PTS were small, single-centre studies without placebo control. We aimed to assess the efficacy of ECS, compared with placebo stockings, for the prevention of PTS. Methods We did a multicentre randomised placebo-controlled trial of active versus placebo ECS used for 2 years to prevent PTS after a first proximal DVT in centres in Canada and the USA. Patients were randomly assigned to study groups with a web-based randomisation system. Patients presenting with a first symptomatic, proximal DVT were potentially eligible to participate. They were excluded if the use of compression stockings was contraindicated, they had an expected lifespan of less than 6 months, geographical inaccessibility precluded return for follow-up visits, they were unable to apply stockings, or they received thrombolytic therapy for the initial treatment of acute DVT. The primary outcome was PTS diagnosed at 6 months or later using Ginsberg's criteria (leg pain and swelling of ≥1 month duration). We used a modified intention to treat Cox regression analysis, supplemented by a prespecified per-protocol analysis of patients who reported frequent use of their allocated treatment. This study is registered with ClinicalTrials.gov , number NCT00143598 , and Current Controlled Trials, number ISRCTN71334751. Findings From 2004 to 2010, 410 patients were randomly assigned to receive active ECS and 396 placebo ECS. The cumulative incidence of PTS was 14·2% in active ECS versus 12·7% in placebo ECS (hazard ratio adjusted for centre 1·13, 95% CI 0·73–1·76; p=0·58). Results were similar in a prespecified per-protocol analysis of patients who reported frequent use of stockings. Interpretation ECS did not prevent PTS after a first proximal DVT, hence our findings do not support routine wearing of ECS after DVT. Funding Canadian Institutes of Health Research.
The reason some patients with deep venous thrombosis (DVT) develop the postthrombotic syndrome is not well understood.
To determine the frequency, time course, and predictors of the postthrombotic ...syndrome after acute DVT.
Prospective, multicenter cohort study.
8 Canadian hospital centers.
387 outpatients and inpatients who received an objective diagnosis of acute symptomatic DVT were recruited from 2001 to 2004.
Standardized assessments for the postthrombotic syndrome using the Villalta scale at 1, 4, 8, 12, and 24 months after enrollment. Mean postthrombotic score and severity category at each interval was calculated. Predictors of postthrombotic score profiles over time since diagnosis of DVT were identified by using linear mixed modeling.
At all study intervals, about 30% of patients had mild (score, 5 to 9), 10% had moderate (score, 10 to 14), and 3% had severe (score >14 or ulcer) postthrombotic syndrome. Greater postthrombotic severity category at the 1-month visit strongly predicted higher mean postthrombotic scores throughout 24 months of follow-up (1.97, 5.03, and 7.00 increase in Villalta score for mild, moderate, and severe 1-month severity categories, respectively, vs. none; P < 0.001). Additional predictors of higher scores over time were venous thrombosis of the common femoral or iliac vein (2.23 increase in score vs. distal calf venous thrombosis; P < 0.001), higher body mass index (0.14 increase in score per kg/m(2); P < 0.001), previous ipsilateral venous thrombosis (1.78 increase in score; P = 0.001), older age (0.30 increase in score per 10-year age increase; P = 0.011), and female sex (0.79 increase in score; P = 0.020).
Decisions to prescribe compression stockings were left to treating physicians rather than by protocol. Because international normalized ratio data were unavailable, the relationship between anticoagulation quality and Villalta scores could not be assessed.
The postthrombotic syndrome occurs frequently after DVT. Patients with extensive DVT and those with more severe postthrombotic manifestations 1 month after DVT have poorer long-term outcomes.
Summary
The performance of a new automated ELISA for a rapid, individual and quantitative measurement of plasma D-dimer (VIDAS D-dimer) has been evaluated. First, a study of 100 patients was ...performed in order to choose the best couple of antibodies in comparison with an already clinically validated ELISA. Then the results were certified in a prospective study including 195 consecutive patients suspected of pulmonary embolism (PE). For a cut-off level of 500 ng/ml VIDAS D-dimer showed a sensitivity of 100% (95% confidence interval 92-100), a specificity of 37.6%, a negative predictive value of 100% (95% CI 93.3-100) and a positive predictive value of 33.1%. During a 6 months’ follow-up no patient (95% CI 0-6.4) with D-dimer <500 ng/ml presented a new suspicion of venous thromboembolic disease. These results suggest that this rapid and single-dose ELISA provides a very useful tool for the clinician to exclude on a day-to-day basis the diagnosis of PE.
PDF
