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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.

The bromodomain and extraterminal domain (BET) family of epigenetic regulators comprises four proteins (BRD2, BRD3, BRD4, BRDT), each containing tandem bromodomains. To date, small molecule inhibitors of these proteins typically bind all eight bromodomains of the family with similar affinity, resulting in a diverse range of biological effects. To enable further understanding of the broad phenotype characteristic of pan-BET inhibition, the development of inhibitors selective for individual, or sets of, bromodomains within the family is required. In this regard, we report the discovery of a potent probe molecule possessing up to 150-fold selectivity for the N-terminal bromodomains (BD1s) over the C-terminal bromodomains (BD2s) of the BETs. Guided by structural information, a specific amino acid difference between BD1 and BD2 domains was targeted for selective interaction with chemical functionality appended to the previously developed I-BET151 scaffold. Data presented herein demonstrate that selective inhibition of BD1 domains is sufficient to drive anti-inflammatory and antiproliferative effects.

Through their function as epigenetic readers of the histone code, the BET family of bromodomain-containing proteins regulate expression of multiple genes of therapeutic relevance, including those involved in tumor cell growth and inflammation. BET bromodomain inhibitors have profound antiproliferative and anti-inflammatory effects which translate into efficacy in oncology and inflammation models, and the first compounds have now progressed into clinical trials. The exciting biology of the BETs has led to great interest in the discovery of novel inhibitor classes. Here we describe the identification of a novel tetrahydroquinoline series through up-regulation of apolipoprotein A1 and the optimization into potent compounds active in murine models of septic shock and neuroblastoma. At the molecular level, these effects are produced by inhibition of BET bromodomains. X-ray crystallography reveals the interactions explaining the structure-activity relationships of binding. The resulting lead molecule, I-BET726, represents a new, potent, and selective class of tetrahydroquinoline-based BET inhibitors.

Dapsone has been shown to possess anti-inflammatory activity in a variety of animal models. It possesses oral anti-oedema activity especially pronounced in novel models of acute inflammation, viz. anti-IgG and reversed passive Arthus oedemas. However, it is not very active in the guinea pig u.v. erythema model. It is effective in chronic models such as adjuvant arthritis and the cotton pellet granuloma although multiple administration may also produce cyanosis. Antipyretic and analgesic effects for dapsone have been demonstrated and are similar to those produced by phenylbutazone. It inhibits zymosan-induced beta-glucuronidase release from cultured macrophages and also the activity of this enzyme. Dapsone does not appear to be ulcerogenic in the rat.

We examined the effects of two prostaglandin synthetase inhibitors, aspirin and oxaprozin, on the development of lupus-like disease in MRL/1 mice. Daily oral administration of 100 mg/kg of these compounds over a period of 3 months significantly reduced thymic lymphoid hyperplasia. In addition, aspirin but not oxaprozin significantly lowered total lymphocyte counts in the peripheral blood. Other drug-related changes, including reduced hyperplasia in the spleen and lymph nodes and an improvement in kidney vasculitis by aspirin, did not reach statistical significance. Neither aspirin nor oxaprozin influenced the circulating levels of anti-ds DNA antibodies or the severity of kidney glomerulonephritis. While the overall effects of these cyclooxygenase inhibitors were not dramatic, the results do indicate that further studies are warranted to determine the precise therapeutic role, if any, for PG-synthetase inhibitors in lupus-like disease.

A comparison of the anti-inflammatory (AI) activity of copper compounds in models of kaolin-induced paw oedema and u.v. erythema in the rat and guinea pig is described. The results demonstrated considerable species variation, the guinea pig being more sensitive to the AI and irritant effects of copper aspirinate and the other copper compounds. The route of administration of these compounds was also an important factor in interpreting AI activity obtained. Indeed, the counter-irritation effects of the copper compounds may be largely responsible for the AI activity obtained after subcutaneous administration. The comparison between copper aspirinate and aspirin, performed in order to determine whether a copper complex of an AI drug was more active than the parent AI compound, failed to produce a clear difference in activity although copper aspirinate was more effective than aspirin in certain cases. It is concluded that this study highlights the complexities of copper therapy against inflammatory processes and furthermore indicates the importance of species, the model of inflammation and route of drug administration in interpreting data obtained with copper containing compounds.

We investigated the therapeutic effect of two gold salts, gold sodium thiomalate (GST, i.m.) and auranofin (p.o.), D-penicillamine (p.o.) and benoxaprofen (p.o.) in rat collagen-induced arthritis using type II collagen from fetal bovine articular cartilage. GST, but not auranofin, reduced hind paw edema and bone pathology. However, auranofin reduced serum copper and zymosan-induced prostaglandin production from peritoneal macrophages. In contrast, GST increased both serum copper and macrophage prostaglandin production by zymosan. Benoxaprofen reduced both hind paw edema and pathology, whereas D-penicillamine was without effect. None of these treatments influenced the circulating level of antibody to type II collagen.

Wy-25,110, the p-OH metabolite of fentiazac was approximately 100 times less potent than fentiazac after oral administration in rat carrageenan edema and 100-130 times less potent as an inhibitor of prostaglandin synthesis by mouse peritoneal macrophages. In addition, Wy-25,110 was one twelfth as active as fentiazac against immunologic-induced inflammation on day 16 in rat adjuvant arthritis. Wy-25,110 was also much less potent than fentiazac when administered intravenously, suggesting that inadequate oral absorption does not account for its lack of potency. Thus it seems unlikely that the p-OH metabolite contributes greatly to the antiinflammatory properties of fentiazac.

1. Exposure of the skin of rats to u.v. light (greater than 295 nm) for 30 s or longer elicited a delayed erythema response, the rate of onset increasing with period of irradiation. The erythema was still present at 24 h and was replaced by scab formation in 48 hours. 2. Both topically applied steroidal and non-steroidal anti-inflammatory drugs reduced the erythema formation when administered immediately after u.v. exposure. Propyl gallate, an antioxidant with sun screening properties in man, also possessed topical anti-erythemic activity. 3. Both steroidal and non-steroidal anti-inflammatory drugs, systemically administered 1 h before u.v. exposure, reduced and erythema. However, the steroidal compounds were less effective than the non-steroids and reduced the intensity of erythema by less than 50%. Antagonists of 5-hydroxytryptamine (5-HT) reduced the erythema but several other drugs with different pharmacological activities were ineffective. 4. Neither topical nor systemic treatments of any of the drugs examined suppressed the scab formation at 48 hours. 5. These results and those using other selective blocking agents indicate that in the mediation of the erythema reaction prostaglandins may play a major role and 5-HT perhaps a minor one but that H1 histamine receptors and alpha- and beta-adrenoceptors have no significant role.

The antiinflammatory activity of the immunomodulatory agent Wy-18,251 (3-(p-chlorophenyl)thiazolo-[3,2-a]benzimidazole-2-acetic acid) was examined using a variety of antiinflammatory, analgesic and antipyretic animal models in comparison to aspirin, levamisole and indomethacin. The acute antiinflammatory and analgesic activity of Wy-18,251 (ED50 = 100-200 mg/kg, p.o.) was similar to aspirin, but in contrast to aspirin Wy-18,251 failed to demonstrate antipyretic activity. Wy-18,251 (10-100 mg/kg, p.o.) also inhibited chronic inflammatory responses in the adjuvant- and collagen-induced arthritis models. Wy-18,251 was a modest inhibitor of prostaglandin biosynthesis but did not inhibit either 5- or 15-lipoxygenase enzymes. Wy-18,251 (up to 480 mg/kg, p.o.) produced little gastrointestinal pathology in 16 h fasted rats. The combined immunomodulatory and antiinflammatory activity of Wy-18,251 suggests that this agent may have therapeutic promise in certain immunoinflammatory diseases including rheumatoid arthritis.

Inhibitors of arachidonic acid (AA) metabolism and other pharmacologic agents were evaluated against ear edema produced in mice by tetradecanoylphorbol acetate (TPA) or AA. Drugs were administered orally and topically either 30 min prior to AA or 30 min after TPA, except for steroids which were administered 2.5-3 hr prior to AA. Several cyclooxygenase (CO) inhibitors including indomethacin, aspirin, piroxicam and timegadine were without effect when administered orally against either irritant; the same drugs inhibited TPA edema when they were administered topically. Mixed CO/lipoxygenase (LO) inhibitors, phenidone and BW755C, were active orally against AA edema (ED50S of 84 and 65 mg/kg, respectively) and against TPA edema (ED50S of 235 and 88 mg/kg, respectively). Phenidone was more active topically against AA edema (ED50, 0.1 mg/ear) than BW755C (ED50, 2.8 mg/ear); however, BW755C was more active topically against TPA edema (ED50, 0.2 mg/ear) than phenidone (ED50, 0.6 mg/ear). Methylprednisolone was very effective in the AA (oral ED50, 17 mg/kg; topical ED50, greater than 1 mg/ear) and TPA models (oral ED50, 4.3 mg/kg; topical ED50, 0.03 mg/ear. MK-447 was topically and orally effective only in the TPA model. Not surprisingly, drugs were more effective topically than orally in both mouse ear edema assays. The models were somewhat selective for CO and CO/LO inhibitors; however, dapsone was orally effective in the ear models, and a number of mediator antagonists and CNS drugs, especially anti-psychotics, were topically active primarily against TPA edema. These models may be useful for the detection of in vivo activity of CO/LO or 5-LO inhibitors.

Copper complexes of a range of ligands have been prepared and evaluated for antiinflammatory activity and irritancy after oral, subcutaneous, and local administration in rats and guinea pigs. The antiinflammatory activities were found to depend on the species used and the route of administration. When nonantiinflammatory ligands were used, the response was generally dose dependent. With D-penicillamine and when the ligands were themselves antiinflammatory in animal models of inflammation--as was the case with flufenamic acid, levamisole, aspirin, L-histidine, and 2-amino-2-thiazoline--differences in antiinflammatory activity were observed between the copper complexes and the free ligands. In some cases, the copper complexes were the more effective. There was a weak correlation between local (subplantar) irritation and the dose of copper but, for four compounds studied in more detail, the response in the local subplantar test and degree of antiinflammatory activity were not related, suggesting that the action of copper is not solely by a counterirritant mechanism. No obvious differences between the activities of copper(I) and copper(II) compounds were observed, suggesting that a common metabolite may be involved in the antiinflammatory action of copper.

Wy-41,770 [(5H-dibenzo[a,d]cyclohepten-5-ylidene)acetic acid], a novel acrylic acid, was compared to indomethacin and aspirin in standard antiinflammatory, analgesic and antipyretic animal models. The acute antiinflammatory, analgesic and antipyretic activity of Wy-41,770 (oral ED50S 50-170 mg/kg) was similar to aspirin; however, it was considerably more potent orally in adjuvant arthritis in the rat (ED50, 16 mg/kg) and urate-induced synovitis in the dog (ED50, 4.5 mg/kg). Wy-41,770 was a weak inhibitor of prostaglandin biosynthesis and did not inhibit either 5- or 15-lipoxygenase. Furthermore, the cellular migration characteristic of carrageenan pleurisy was not affected by Wy-41,770. Unlike a majority of NSAIDs, it produced no gastric irritation in rats after either acute or chronic oral administration over the range 400-800 mg/kg. The major mechanism of action of Wy-41,770 has yet to be identified but does not seem to involve interference of arachidonic acid metabolism.

11 beta-Hydroxy-16 alpha, 17 alpha, 21-trimethyl-pregna-1,4-diene-3,20-dione(ORG 6216) is a novel type of anti-inflammatory steroid which displays a dissociation of local from systemic effects in a range of animal models. Moreover, ORG 6216 is exceptional in that it has not shown any significant atrophogenic activity in the skin when administered either topically or intracutaneously in animal models.

The effects of a number of steroids administered intra-articularly in a chronic model of fibrin-induced monoarticular arthritis in the rabbit have been investigated. Org 6216 hydrocortisone acetate, prednisolone tertiary butyl acetate and triamcinolone hexacetonide each suppressed the joint swelling produced 14 days after antigen challenge. These anti-inflammatory effects lasted for at least 7 days. Hydrocortisone semisuccinate was inactive in this model. In addition, the effects of the same compounds and several other anti-inflammatory steroids and indomethacin administered locally with adjuvant was assessed on the resultant paw oedema produced in the rat. The local anti-inflammatory activity, the duration of action and the systemic effects of these drugs varied considerably and only Org 6216, hydrocortisone acetate, prednisolone tertiary butyl acetate and indomethacin produced anti-inflammatory effects throughout the 4 days of the experiments and were devoid of significant adrenolytic and thymolytic activity.

The development of novel anti-inflammatory drugs (AID) has been claimed to be dependent on the discovery of models of inflammation that differ from those currently used for drug screening, e.g. carrageenen paw oedema and u.v. erythema. We have thus evaluated the effect of a variety of drugs in a number of novel models of inflammation in the rat produced in the hind paw. We have utilized kaolin, zymosan, anti-rat IgG (anti-IgG) and the Reversed Passive Arthus (RPA) reaction to produce these oedema models. We found that the non-steroidal AID's, e.g. aspirin, flufenamic acid, indomethacin, naproxen, and phenylbutazone, were active in all four tests. Of the nine novel AID examined, levamisole and tetramisole demonstrated considerable activity in all four tests and dapsone was especially active in the anti-IgG and RPA tests. In contrast, the anti-rheumatic d-penicillamine was inactive in all four models. Each of the ten compounds tested which has been claimed to influence complement function, was active in the RPA but not in the kaolin model. These results are discussed in the context of the aetiology of each oedema and the suspected mode of action of the various drugs.