Discovery of a Novel Bromodomain and Extra Terminal Domain (BET) Protein Inhibitor, I-BET282E, Suitable for Clinical Progression.

The functions of the bromodomain and extra terminal (BET) family of proteins have been implicated in a wide range of diseases, particularly in the oncology and immuno-inflammatory areas, and several inhibitors are under investigation in the clinic. To mitigate the risk of attrition of these compounds due to structurally related toxicity findings, additional molecules from distinct chemical series were required. Here we describe the structure- and property-based optimization of the in vivo tool molecule I-BET151 toward I-BET282E, a molecule with properties suitable for progression into clinical studies.

Pharmacological properties of the enhanced-affinity glucocorticoid fluticasone furoate in vitro and in an in vivo model of respiratory inflammatory disease.

Fluticasone furoate (FF) is a novel enhanced-affinity glucocorticoid that has been developed as topical therapy for allergic rhinitis. The pharmacological properties of FF have been investigated using a number of in vitro experimental systems. FF demonstrated very potent glucocorticoid activity in several key pathways downstream of the glucocorticoid receptor (GR) as follows: the transrepression nuclear factor-kappaB (NF-kappaB) pathway, the transactivation glucocorticoid response element pathway, and inhibition of the proinflammatory cytokine tumor necrosis factor-alpha. Furthermore, FF showed the greatest potency compared with other glucocorticoids for preserving epithelial integrity and reducing epithelial permeability in response to protease- and mechanical-induced cell damage. FF showed a 30- to >330,000-fold selectivity for GR-mediated inhibition of NF-kappaB vs. the other steroid hormone receptors, substantially better than a number of other clinically used glucocorticoids. In studies examining the respiratory tissue binding properties of glucocorticoids, FF had the largest cellular accumulation and slowest rate of efflux compared with other clinically used glucocorticoids, consistent with greater tissue retention. The in vivo anti-inflammatory activity of FF was assessed in the Brown Norway rat ovalbumin-induced lung eosinophilial model of allergic lung inflammation. At a dose of only 30 microg, FF achieved almost total inhibition of eosinophil influx in the lung, an inhibition that was greater than that seen with the same dose of fluticasone propionate. In conclusion, the potent and selective pharmacological profile of FF described here could deliver an effective, safe, and sustained topical treatment of respiratory inflammatory diseases such as allergic rhinitis and asthma.

Dissociated nonsteroidal glucocorticoid receptor modulators; discovery of the agonist trigger in a tetrahydronaphthalene-benzoxazine series.

The tetrahydronaphthalene-benzoxazine glucocorticoid receptor (GR) partial agonist 4b was optimized to produce potent full agonists of GR. Aromatic ring substitution of the tetrahydronaphthalene leads to weak GR antagonists. Discovery of an "agonist trigger" substituent on the saturated ring of the tetrahydronaphthalene leads to increased potency and efficacious GR agonism. These compounds are efficacy selective in an NFkB GR agonist assay (representing transrepression effects) over an MMTV GR agonist assay (representing transactivation effects). 52 and 60 have NFkB pIC(50) = 8.92 (105%) and 8.69 (92%) and MMTV pEC(50) = 8.20 (47%) and 7.75 (39%), respectively. The impact of the trigger substituent on agonism is modeled within GR and discussed. 36, 52, and 60 have anti-inflammatory activity in a mouse model of inflammation after topical dosing with 52 and 60, having an effect similar to that of dexamethasone. The original lead was discovered by a manual agreement docking method, and automation of this method is also described.

MRI quantification in vivo of corticosteroid induced thymus involution in mice: correlation with ex vivo measurements.

Thymus involution is a useful marker of transactivation-mediated side effects in preclinical therapeutic index testing of new anti-inflammatory glucocorticosteroids, and is usually measured post mortem. We have validated the use of MRI for non-invasive in vivo measurement of mouse thymus involution induced by dexamethasone (DEX). Tl-weighted spin echo 7 T images provided satisfactory contrast between thymus and surrounding connective tissue and fat. Increasing doses of DEX caused thymus involution, reflected in MRI volume (87+/-14, 33+/-10, 28+/-6, 16+/-7 microl in dosage groups of Cremophor vehicle, 1, 10 and 30 mg/kg subcutaneous respectively, n=6/group, mean+/-standard deviation) and post mortem wet weight (64+/-12, 33+/-6, 25+/-9, 23+/-8 mg). Correlation between MRI volumes and wet weights was very good (r=0.842). Measuring pre-dose MRI volumes and then assessing DEX effects as post-dose change from baseline produced no statistical advantage relative to considering post-dose MRI thymus volume alone, probably due to variability in pre-dose baseline values compounding post-dose variability. Smaller group sizes were sufficient to achieve a given statistical power using MRI post-dose volume than using wet weight, suggesting a role for MRI in differentiating the effects of compounds which produce similar effects, or in contexts where the use of large groups of animals is impractical or ethically unacceptable.