Design, synthesis and activity of a potent, selective series of N-aryl pyridinone inhibitors of p38 kinase

Bioorganic & Medicinal Chemistry Letters 21 (2011) 4059–4065

Contents lists available at ScienceDirect

Bioorganic & Medicinal Chemistry Letters journal homepage: www.elsevier.com/locate/bmcl

Design, synthesis and activity of a potent, selective series of N-aryl pyridinone inhibitors of p38 kinase Shaun R. Selness a,⇑, Terri L. Boehm a, John K. Walker a, Balekudru Devadas a, Richard C. Durley a, Ravi Kurumbail b, Huey Shieh b, Li Xing b, Michael Hepperle a, Paul V. Rucker a, Kevin D. Jerome a, Alan G. Benson a, Laura D. Marrufo a, Heather M. Madsen a, Jeff Hitchcock a, Tom J. Owen a, Lance Christie a, Michele A. Promo a, Brian S. Hickory a, Edgardo Alvira a, Win Naing a, Radhika Blevis-Bal a, Rajesh V. Devraj a, Dean Messing c, John F. Schindler d, Jeffrey Hirsch d, Matthew Saabye d, Sheri Bonar d, Elizabeth Webb d, Gary Anderson d, Joseph B. Monahan b,d a

Department of Medicinal Chemistry, Pfizer Corporation, 700 Chesterfield Parkway West, Chesterfield, MO 63017, USA Structural and Computational Chemistry, Pfizer Corporation, 700 Chesterfield Parkway West, Chesterfield, MO 3017, USA c Department of Pharmcokinetics and Drug Metabolism, Pfizer Corporation, 700 Chesterfield Parkway West, Chesterfield, MO 63017, USA d Inflammation Biology, Pfizer Corporation, 700 Chesterfield Parkway West, Chesterfield, MO 63017, USA b

a r t i c l e

i n f o

Article history: Received 2 March 2011 Revised 23 April 2011 Accepted 26 April 2011 Available online 13 May 2011 Keywords: p38 kinase Inflammation Rheumatoid arthritis TNFa Pyridinones

a b s t r a c t A series of N-aryl pyridinone inhibitors of p38 mitogen activated protein (MAP) kinase were designed and prepared based on the screening hit SC-25028 (1) and structural comparisons to VX-745 (5). The focus of the investigation targeted the dependence of potency and metabolic stability on the benzyloxy connectivity, the role of the C-6 position and the substitution pattern on the N-phenyl ring. Further optimization produced the highly selective and potent pyridinones 2 and 3. These inhibitors exhibited activity in both acute and chronic models of inflammation. Ó 2011 Elsevier Ltd. All rights reserved.

The correlation of elevated levels of the cytokine tumor necrosis factor-a (TNFa) with the pathophysiology of a number of inflammatory diseases has been studied for over two decades.1 The efficacy observed for marketed anti-TNFa therapies, such as etanercept, adalimumab and inflixamab, in rheumatoid arthritis, psoriasis and Crohn’s disease has established the important role of TNFa in these diseases and validates approaches to limit its production as potential therapeutic mechanisms.2 The role of a number of stress-activated pathways in the production of TNFa has been extensively investigated and has yielded several potential therapeutic targets such as p38a.3 In this Letter, we discuss our progression from the screening hit, SC-25028 (1) to the N-phenyl pyridinones such as 2 and 3 (Fig. 1). The initial lead, 1, was identified from a high-throughput full file screen and demonstrated low micro molar activity against p38a. Additional profiling of 1 revealed that it possessed a high degree of selectivity against a panel of over 200 kinases. The binding

mode of 1 with p38a has been disclosed in a previous communication.4 This structural data was used to optimize the potency of the

⇑ Corresponding author. E-mail address: [email protected] (S.R. Selness). 0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmcl.2011.04.120

Figure 1. HTS hit SC-25028 (1) and N-aryl pyridinone leads.

4060

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065

Scheme 1. Reagents and conditions: (a) 2,6-difluoroaniline, o-dichlorobenzene, 165 °C, 20 min, 35%; (b) 2,6-dimethyl or 2,6-dichloroaniline, o-dichlorobenzene, p-toluenesulfonic acid, 165 °C, 3 h, 28–30%; (c) NBS, CH2Cl2, 1 h, 25 °C, 77–79%; (d) benzyl, 4-fluorobenzyl, or 2,4-difluorobenzylbromide, DMF, K2CO3, 25 °C, 45–65%; (e) NCS, CH2Cl2, isopropanol, reflux, 3 h, 62%; (f) 2,4-difluorobenzylbromide, DMF, K2CO3, 25 °C, 65%.

Figure 2. Historical p38 inhibitors.

series and was used to identify key binding contacts that provide the rational for the high degree of selectivity and specificity exhibited by this series. Improving the metabolic stability of 1 was a primary objective and drove the decision to replace the N-benzyl group with an N-phenyl group. Previous work on this series had identified the 2,4-difluoro substitution on the O-benzyl group as optimal for both potency and metabolic stability. These investigations led to the generation of 4, a potent and selective inhibitor of p38a (Fig. 2).4 High clearance (in rats) was identified as one of the liabilities of this N-benzyl pyridinone class. We hypothesized that N-debenzylation was a potential contributor to the observed high clearances in rat pharmacokinetic studies. In order to test this hypothesis, a series of N-phenyl pyridinone derivatives were prepared and evaluated for their activity, selectivity, in vitro stability and pharmacokinetic profiles. Initially, 2,6-disubstituted N-phenyl analogs were prepared based on comparisons to the fused biaryl class of p38 inhibitors represented by 5, 6 and 7.5 The data for these analogs is shown in Table 1. The potency exhibited by these compounds required the development of an assay with improved sensitivity relative to previously reported assays.6 A cascade assay with p38a and MK-2 was developed to accomplish this objective (with a readout of phosphor-HSP27 peptide).7 The final concentration of p38a in the assay was 100 pM, thus allowing for the detection of low nM inhibitors of p38a. Compounds 8–13 demonstrated that 2,6-disub-

stitution was tolerated and afforded improved potency compared to that observed for 4 (p38a IC50 = 46 nM) as illustrated by 13. Scheme 1 outlines the synthetic sequences used to prepare the initial N-aryl analogs 8–13 (Table 1). Condensation of the corresponding 2,6-disubstituted aniline with 4-hydroxy-6-methyl-2Hpyran-2-one followed by halogenation with either NCS or NBS yielded the N-phenyl-3-halo-4-hydroxy-6-methyl pyridinones 15–18. O-Alkylation of the 4-hydroxy group with the suitable benzyl halide afforded the N-phenyl-3-chloro-4-benzyloxy or N-phenyl-3-bromo-4-benzyloxy pyridinones 8–13. Based on docking of 9 with p38a, targeting Asp112 and Asn115 (to improve potency) appeared to be feasible via elaboration of the 4-position of the N-phenyl group ( Fig. 3). As shown in Table 2 these analogs possessed significant activity against p38. The piperazine derivatives, 19 and 20, did not provide any advantage over the smaller N,N-dimethyl derivative, 21, the phenol 22 or the phenyl ethers, 23 and 24. However, based on the activity (and lower metabolic stability) of these analogs 2,4,6-trisubstitution did not appear to offer any significant advantages over the 2,6-disubstituted analogs. The N-phenyl trisubstituted analogs 19–24 were prepared as shown in Scheme 2. Under similar condensation conditions 4-hydroxy-6-methyl-2H-pyran-2-one was allowed to react with 2,4,6-trifluoroaniline followed by alkylation with 2,4-difluoroben-

Table 1 2,6-Bis ortho substituted 4-benzyloxy-N-aryl pyridinones

a

Compound

R1

R2

R3

X1, X2

p38a cascadea IC50 (lM)

8 9 10 11 12 13

2,4-Di-F–PhCH2 2,4-Di-F–PhCH2 PhCH2 4-F–PhCH2 2,4-Di-F–PhCH2 2,4-Di-F–PhCH2

Br Cl Br Br Br Br

CH3 CH3 CH3 CH3 CH3 CH3

F, F F, F Cl, Cl Cl, Cl Cl, Cl CH3, CH3

0.003 0.004 0.030 0.006 0.001 0.002

For assay conditions please see Ref. 7.

4061

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065

Figure 3. Docked model of 9 with p38a showing residues Asp112 and Asn 115.

Table 2 4-Substituted 2,6-difluoro N-aryl pyridinones

a

Compound

R1

R2

p38a cascadea IC50 (lM)

19 20 21 22 23 24

4-N-Me–piperazine 4-N-Me–piperazine –N(CH3)2 –OH –OCH2CH2OH –OCH2C(O)NH2

Br Cl Br Br Br Br

0.014 0.023 0.008 0.015 0.007 0.003

Scheme 2. Reagents and conditions: (a) 2,4,6-trifluoroaniline, o-dichlorobenzene, 165 °C, 1 h, 33%; (b) 2,4-difluorobenzyl bromide, K2CO3, DMF, 25 °C, 77%; (c) excess 4-methylpiperazine or 2.0 N dimethylamine in THF, K2CO3, 25 °C, 34–52%; (d) NBS, CH2Cl2, 25 °C, 50–65%; (e) NCS, dichloroacetic acid, CH2Cl2, 25 °C, 16 h, 57–62%; (f) KOSiMe3, THF, 45 °C, 1 h, 37%; (g) BrCH2CH2OH (5 equiv), K2CO3 (6 equiv), DMF, 25 °C, 48 h, 27%; (h) BrCH2C(O)NH2 (1.3 equiv), K2CO3, DMF, 25 °C, 16 h, 51%.

Table 3 6-Substituted pyridinones

For assay conditions please see Ref. 7.

zyl bromide to afford 25. Displacement of the 4-fluoro group with either N-methylpiperazine or dimethylamine followed by subsequent halogenation with either NCS or NBS gave the N-phenyl 4substituted pyridinones 19–21. Alternatively, bromination with NBS and displacement with potassium trimethylsilanoate provided the phenol, 22. Alkylation of 22 with either 2-bromoethanol or 2-bromoacetamide generated the alkoxyl analogs 23 and 24. The C-6 position of the pyridinone was identified as a potential site for cytochrome P450-mediated metabolism. Chemistry was developed to prepare the C-6 oxidized analogs, 26 and 2, as well as the methylamine derivatives, 27–29, (Table 3). The potential metabolites showed retention of activity consistent with a model that orients the C-6 substituents towards the solvent front ( Fig. 3). The alkyl amino derivatives also possessed significant activity against p38a. Alkylation of 14 with 2,4-difluorobenzyl bromide generated the pyridinone intermediate 30 (Scheme 3). Oxidation of the C-6 methyl of 21 with SeO2 followed by reduction with NaBH4 cleanly gave the alcohol 31 (initial oxidation with SeO2 generated a mixture of the alcohol and the aldehyde). Halogenation of 31 with either NBS or NCS afforded the pyridinones 26 and 2, respectively. Oxidation of the primary alcohol in 26 and 2 followed by reductive amination with dimethylamine or morpholine yielded the C-6 aminomethyl derivatives, 27–29. We next focused on the importance of the benzyloxy linker. Based on modeling of the amine and ethylene linkers versus the benzyloxy linker, the trajectory of the benzyloxy group appeared

Compound

R

X

p38a cascadea IC50 (lM)

26 2 27 28

–CH2OH –CH2OH –CH2N(CH3)2 –CH2N(CH3)2

Br Cl Br Cl

0.005 0.008 0.006 0.008

Br

0.009

29 a

For assay conditions please see Ref. 7.

to be optimal for occupying the lipophilic pocket beyond the gatekeeper residue, Thr103. Both the benzylamine and ethylene linkers were investigated and found to be significantly less active than the corresponding benzyloxy linker. We then turned our attention to the necessity of the 2,6-disubstitution on the N-phenyl group (Table 4). A set of compounds lacking ortho-substitution on the N-phenyl ring were prepared. These compounds were designed with the potential to engage Asp112 and/or Asn113 from either the 3- or the 4-position of the N-phenyl ring. These analogs were accessed via the readily available amino benzoates. The activity profiles showed a consistent dependence on the substitution pattern and the trajectory of the functional group. The parent aminomethyl compounds, 32 and 33, as well

4062

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065 Table 5 Cell activity (hPBMCs) and metabolic stability (as measured by incubation with human or rat liver microsomes) of selected N-aryl pyridiones

a b

Scheme 3. Reagents and conditions: (a) SeO2, dioxane, sealed tube, blast shield, 170 °C, 1.5 h; (b) NaBH4, MeOH, 0 °C ? rt, 4 h, 44% for two steps; (c) NBS, CH3CN, 0 °C, 2 h, 91%; (d) NCS, CH3CN, 25 °C, 4 h, 59%; (e) Dess–Martin periodinane, CH2Cl2, 0 °C, 4 h, 70–90%; (f) morpholine or 2 N dimethylamine in THF, CH2Cl2, NaBH(OAc)3, HOAc, 25 °C, 12–16 h, 30–50%.

as their corresponding acyl and urea derivatives 34–39, exhibited greater activity for the 4-substituted compounds. In contrast to this trend, the 3-carboxamide derivatives were more active than the corresponding 4-carboxamides as demonstrated by the analogs 3 and 40–44. Scheme 4 shows the preparation of the N-(4-substituted) phenyl pyridinones. Condensation of methyl-4-aminobenzoate with 4-hydroxy-6-methyl-2H-pyran-2-one followed by alkylation with 2,4-difluorobenzyl bromide generated the pyridinone intermediate, 45. Bromination of 45 with NBS followed by hydrolysis of the ester provided the carboxylic acid, 46. The acid intermediate 46 was coupled with ammonia, methylamine or dimethylamine to afford the amides 40, 41 and 43. Reduction of 40 with borane yielded the amino methyl derivative 32. Treatment of 32 with 2,2,2-trichloroacetyl isocyanate followed by addition of ammonium hydroxide generated the primary urea, 38. Acylation of 32

Compound

TNF release from hPBMCs IC50 (lM)a

HLM (% remaining)b

RLM (% remaining)b

13 8 9 26 2 23 27 34 36 3 42

0.025 0.022 0.017 0.025 0.045 0.061 0.050 0.091 0.118 0.064 0.045

3 60 74 39 70 87 0 88 97 100 95

1 80 87 65 69 96 0 83 91 97 92

For assay conditions please see Ref. 8. For assay conditions please see Ref. 9.

with 2-acetoxy acetylchloride gave the amide 47. Hydrolysis of 47 provided the hydroxy acetamide derivative 34. Coupling of 32 with N-(tert-butoxycarbonyl)glycine gave the amide 48 which was deprotected to afford 36. An analogous series of N-(3-substituted)phenyl pyridinones was prepared as outlined in Schemes 5 and 6. Condensation of ethyl-3-aminobenzoate with 4-hydroxy-6-methyl-2H-pyran-2one followed by alkylation with 2,4-difluorobenzyl bromide gave the pyridinone intermediate 49. Halogenation and hydrolysis of 49 afforded the carboxylic acid 50. Coupling of 50 with ammonia, methylamine or dimethylamine provided the amide analogs, 3, 42 and 44, respectively. Condensation of 3-hydroxymethylaniline with 4-hydroxy-6-methyl-2H-pyran-2-one followed by subsequent benzylation with 2,4-difluorobenzyl bromide generated the alcohol 51. The primary amine, 52, was generated from 51 via conversion of the alcohol to the corresponding chloride with 2,4,6-trichlorotriazine followed by treatment with ammonia. Halogenation of 52 with NBS generated the bromide 33. The amine 33 was acylated with acetoxyacetyl chloride to generate the amide 53. Subsequent hydrolysis of 53 provided the hydroxyacetamide 35. Polymer bound carbodiimide catalyzed coupling of 33 with N-(tert-butoxycarbonyl)glycine yielded the amide 54 which, upon treatment with 4 N HCl in dioxane, generated the glycinamide

Table 4 3- And 4-substituted N-phenyl pyridinones

a

Compound

R1

R2

p38a cascadea IC50 (lM)

32 33 34 35 36 37 38 39 40 3 41 42 43 44

–CH2NH2 H –CH2NHC(O)CH2OH H –CH2NHC(O)CH2NH2 H –CH2NHC(O)NH2 H –C(O)NH2 H –C(O)NHCH3 H –C(O)N(CH3)2 H

H –CH2NH2 H –CH2NH(O)CCH2OH H –CH2NH(O)CCH2NH2 H –CH2NH(O)CNH2 H –C(O)NH2 H –C(O)NHCH3 H –C(O)N(CH3)2

0.051 0.681 0.020 0.175 0.015 0.261 0.142 0.251 0.122 0.012 0.126 0.017 0.746 0.102

For assay conditions please see Ref. 7.

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065

4063

Scheme 5. Reagents and conditions: (a) ethyl-3-aminobenzoate, 1,2-dichlorobenzene, 165 °C, 15 min, 37%; (b) 2,4-difluorobenzylbromide, DMF, K2CO3, 25 °C, 50%; (c) NBS, CH3CN, 1 h, 25 °C, 90%; (d) KOSiMe3, THF, 75%; (e) 2-chloro-4,6-dimethoxytriazine, 4-methylmorpholine, THF, 1.5 h, then NH4OH, 30 min, 93%; (f) methyl or dimethylamine, PS-carbodiimide resin, HOBt, DMF rt, 15 min; then add, THF, PS-polyamine resin, PS-polyisocyante resin, 60% two steps.

Scheme 4. Reagents and conditions: (a) methyl-4-aminobenzoate, 1,2-dichlorobenzene, 165 °C, 15 min, 35%; (b) 2,4-difluorobenzylbromide, DMF, K2CO3, 25 °C, 50%; (c) NBS, CH3CN, 1 h, 25 °C, 90%; (d) KOSiMe3, THF, 70%; (e) methyl or dimethylamine, PS-carbodiimide resin, HOBt, DMF rt; then filter, THF PS-polyamine resin, PS-polyisocyante resin, 20-25% two steps; (f) 2-chloro-4,6-dimethoxy-1,3,5triazine, 4-methylmorpholine, THF, 1.5 h, then NH4OH, 30 min, 95%; (g) BH3
THF, THF, 0 °C ? reflux, 56%; (h) acetoxyacetyl chloride or N-(tert-butoxycarbonyl)glycine, PS-carbodiimide resin, HOBt, iPr2Net, DMF rt, 16 h; (i) K2CO3, MeOH, 84%; (j) 4 N HCl–Dioxane, 24%; (k) 2,2,2-trichloroacetyl isocyanate, CH2Cl2, rt, 30 min, then add NH4OH, rt, 3 h, 14%.

derivative, 37. Treatment of 33 with trimethylsilyl isocyanate in the presence of N-methylmorpholine afforded the primary urea 39. Potent compounds in the enzyme assay were evaluated for cellular activity and metabolic stability (Table 5).8,9 In general, most compounds potently (<100 nM) inhibited the release of TNFa from human peripheral blood monocytes (hPBMC). Relative to 13, the compounds in Table 6 exhibited improved stability upon incubation with either human or rat liver microsomes. The sole exception being 27 which, presumably, suffered from oxidative demethylation of the N,N-dimethylamino group. Compounds 3, 36 and 42 exhibited remarkable metabolic stability while retaining cellular activity. This same set of compounds from above was evaluated in a rat lipopolysaccharide (rLPS) model of inflammation (Table 6).10 The rLPS model served as a convenient pharmacodynamic screen for our team and allowed for the evaluation of compounds for their duration of effect at various pre-dose time points prior to challenge with LPS. A wide range of activity was observed and was consistent with the trends established for metabolic stability. Not surprisingly, the less stable compounds, 13 and 33, required higher doses

Scheme 6. Reagents and conditions:(a) 3-hydroxymethyl aniline, H2O, 100 °C, 48 h, 21%; (b) 2,4-difluorobenzylbromide, acetone, Cs2CO3, 25 °C, 38%; (c) 2,4,6-trichloro1,3,5-triazine, 4-methylmorpholine, DMF, CH2Cl2, 2 h, 85%; (d) NH3, MeOH, rt, 24 h, 99%; (e) NBS, CH3CN, 25 °C, 0 °C ? rt, 1.5 h, 43%; (f) acetoxyacetyl chloride or N-(tert-butoxycarbonyl)-glycine, PS-carbodiimide resin, HOBt, N-methylmorpholine, DMAC–CH2Cl2, rt, 4 h; (g) K2CO3, MeOH, 84%; (h) 4 N HCl–Dioxane, 24%; (i) trimethylsilyl isocyante, N-methylmorpholine, THF, rt, 2 h, 93%.

and/or shorter pre-dose times. Compounds such as 8 and 12 (data not shown for 12) exhibited modest inhibition at 5 mpk. In contrast to the Vertex series, the 2,6-disubstituted N-aryl pyridinone analogs possessed excellent in vitro activity but suffered from a lack of translation in vivo (with compound 9 being an exception). The more stable compounds, such as 9 and 3, showed robust inhibition at longer pre-dose times and lower doses ( 4 h and 5 mpk). Several exceptions to this trend included compounds 23 and 40.

4064

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065 Table 6 Pharmacokinetics (male Sprague–Dawley rats) and pharmacodynamics (acute rat lipopolysaccharide model of inflammation) of selected N-aryl pyridiones11 Compound

13 8 9 26 2 23 27 34 36 3 42 a b

Rat pharmacokinetics (i.v. and p. o.)

Rat LPS model (p. o.)b

CL (mL/min/kg)

t½ (h)

Suspension dose F (%)

Dose (mpk)

Predose time (@

— 28.7 12.8 4.0 5.9 — — — — 9.34 8.1

— 1.9 1.8 8.9 1.5 — — — — 3.4 3.1

— 19 21 19 32 — — — — 7, 93a 3

20 5 5 5 5 5 15 5 5 5 5

2 4 6 4 4 4 4 4 4 4 4

h)

Inhibition of TNFa release (%) 66 38 83 93 81 44 69 43 64 89 70

Dosed in solution (i.v. 5 mpk and p.o. 5 mpk). For assay conditions please see Ref. 10.

The corresponding primary alcohols of 23 and 40 are potential sites for phase II metabolism which is not detected typically in liver microsomal assays. The pharmcokinetic profiles of a select number of compounds were determined in male Sprague–Dawley rat (i.v. and p.o. routes of administration, Table 6). The data are consistent with the in vitro RLM stability data as exemplified by 8 and 26. The more stable 26 had a very low clearance (4.0 mL/min/kg) compared to 8 (28.7 mL/min/kg). The low to moderate bioavailabilities exhibited by this class of compounds is primarily attributed to the relatively low solubilities associated with these compounds (<10 lg/mL). This is supported by the oral suspension dosing compared to oral solution dosing for 3. Crystalline 3, when dosed via oral suspension, had very low bioavailability; however, oral solution dosing of this compound demonstrated high bioavailability. This data suggests oral absorption is limited mainly by solubility, not permeability or metabolism. Both 2 and 3 demonstrated efficacy in a rat strep cell wall model of arthritis (33% and 40% incidence, respectively, at 60 mpk/day).12 The overall kinase selectivities of 2 and 3 were comparable to that previously reported for the N-benzyl analog, 4.4,13 In summary, a series of potent, selective and stable N-aryl pyridinone inhibitors of p38a were generated to address liabilities associated with our previously described N-benzyl pyridinone series. This series was metabolically stable in vitro and in vivo. These compounds demonstrated significant activity in both acute (rLPS) and chronic (rSCW) models of inflammation. Work in this that series ultimately led to the identification of a clinical candidate which will be disclosed in subsequent publications.

6.

7.

8.

References and notes 1. (a) Arend, W. P.; Dayer, J. M. Arthritis Rheum. 1990, 33, 305; (b) Firestein, G. S.; Alvaro-Gracia, J. M.; Maki, R. J. Immunol. 1990, 144, 3347; (c) Rutgeerts, P.; D’Haens, G.; Targan, S.; Vasiliauskas, E.; Hanauer, S. B.; Present, D. H.; Mayer, L.; Van Hogezand, R. A.; Braakman, T.; DeWoody, K. L.; Shaible, T. F.; Van Deventer, S. J. H. Gastroenterology 1999, 117, 761. 2. Ulfgren, A. K.; Andersson, U.; Engstrom, M.; Klareskog, L.; Maini, R. N.; Taylor, P. C. Arthritis Rheum. 2000, 43, 2391. 3. (a) Foster, M. L.; Halley, F.; Souness, J. E. Drug News Perspect. 2000, 13, 488; (b) Lee, J. C.; Laydon, J. T.; McDonnell, P. C.; Gallagher, T. F.; Kumar, S.; Green, D.; MeNulty, D.; Blumenthal, M. J.; Heys, J. R.; Landvatter, S. W.; Strickler, J. E.; McLaughlin, M. M.; Siemens, I. R.; Fisher, S. M.; Livi, G. P.; White, J. R.; Adams, J. L.; Young, P. R. Nature 1994, 372, 739. 4. Selness, S. R.; Devraj, R. V.; Monahan, J. B.; Boehm, T. L.; Walker, J. K.; Devadas, B.; Durley, R. C.; Kurumbail, R.; Shieh, H.; Xing, L.; Hepperle, M.; Jerome, K. D.; Benson, A. G.; Marrufo, L. D.; Madsen, H. M.; Hitchcock, J.; Owen, T. J.; Christie, L.; Promo, M. A.; Hickory, B. S.; Alvira, E.; Naing, W.; Blevis-Bal, R. Bioorg. Med. Chem. Lett. 2009, 19, 5851. 5. (a) Bemis, G. W.; Salituro, F. G.; Duffy, J. P.; Cochran, J. E.; Harrington, E. M.; Murcko,. M. A.;Wilson, K. P.; Su, M.; Galullo, V. P. U.S. Patent 7,365,072 B2,

9.

10.

2008.; (b) Bemis, G. W.; Salituro, F. G.; Duffy, J. P.; Harrington, E. M. U.S. Patent 6,147,080, 2000.; (c) Colletti, S. L.; Frie, J. L.; Dixon, E. C.; Singh, S. B.; Choi, B. K.; Scapin, G.; Fitzgerald, C. E.; Kumar, S.; Nichols, E. A.; O’Keefe, S. J.; O’Neill, E. A.; Porter, G.; Samuel, K.; Schmatz, D. M.; Schwartz, C. D.; Shoop, W. L.; Thompson, C. M.; Thompson, J. E.; Wang, R.; Woods, A.; Zaller, D. M.; Doherty, J. B. J. Med. Chem. 2003, 46, 349; (d) Natarajan, S. R.; Heller, S. T.; Nam, K.; Singh, S. B.; Scapin, G.; Patel, S.; Thompson, J. E.; Fitzgerald, C. E.; O’Keefe, S. J. Bioorg. Med. Chem. Lett. 2006, 16, 5809. Full disclosure of earlier assay methods is made in the following patent application: Devadas, Balekudru; Walker, John; Selness, Shaun, R.; Boehm, Terri L.; Durley, Richard C.; Devraj, Rajesh; Hickory, Brian S.; Rucker, Paul V.; Jerome, Kevin D.; Madsen, Heather M.; Alvira, Edgardo; Promo, Michele A.; Blevis-Bal, Radhika M.; Marrufo, Laura D.; Hitchcock, Jeff; Owen, Thomas; Naing, Win; Xing, Li; Shieh, Huey S.; Sambandam, Aruna; Liu, Shuang; Scott, Ian L.; Mcgee, Kevin F. PCT Int. Appl. 2005, 968, pp. WO 2005018557. p38a/MK2 cascade assay: The ability of compounds to inhibit activated p38a was evaluated using a p38a/MK2 cascade assay format. The kinase activity of p38a was determined by its ability to phosphorylate/activate unactivated MK2. Activation of MK2 by p38a was measured by following the phosphorylation of a fluorescently-labelled, MK2 specific peptide substrate, Hsp27 peptide (FITCKKKALSRQLSVAA). The phosphorylation of the Hsp27 peptide was quantified using the Caliper LabChip 3000. Kinase reactions were carried out in a 384-well plate (Matrical, MP101-1-PP) in kinase buffer (20 mM HEPES pH 7.5, 10 mM MgCl2, 0.0005% Tween-20, 0.01% BSA, 1 mM DTT, and 2% DMSO). The inhibitors were varied between 0.2 and 10,000 nM, while the Hsp27 peptide substrate, MgATP, and unactivated MK2 were held constant at 1, 10, and 1 nM, respectively. Reactions were initiated by the addition of activated p38a to a final concentration of 6 pM. Kinase reactions were incubated at room temperature and quenched after 60 minutes by the addition of stop buffer (180 mM HEPES, 30 mM EDTA, and 0.2% Coating Reagent-3). In vitro cell activity: Human whole blood (HWB) was collected from two healthy donors in sodium heparinized tubes (BD Biosciences, Franklin Lakes, NJ), and PBMCs were isolated by Ficoll separation. Cells were washed in DPBS, resuspended in DMEM containing 5% endotoxin-free fetal bovine serum and 10 lL penicillin-streptomycin, and plated at 2.5  105 cells/well in 96-well tissue culture plates. Cells were pretreated with increasing concentrations of compound (0.0001–25 lM) for 1 h before the 18 h stimulation with 22 ng/ml lipopolysaccharide (LPS, Sigma Aldrich, St. Louis, MO). Final Me2SO concentration in cell assay was 0.25%. Secreted TNF-a was measured by MSD technology (MSD, Gaithersburg, MD). IC50s were determined using an internal data analysis program (Pfizer, St. Louis). Metabolic stability was assessed in vitro by incubating 2 lM test compound with human or rat liver microsomes, NADPH and buffer at 37 °C for 45 min and measuring percent compound remaining by a precipitation procedure followed by LC/MS analysis. Adult male Lewis rats (Harlan Sprague Dawley, Indianapolis, IN) (225–250 g) were used in these studies. Rats were fasted 18 h prior to oral dosing, and allowed free access to water throughout the experiment. Each treatment group consisted of five animals. 10 was prepared as a suspension in a vehicle consisting of 0.5% methylcellulose, (Sigma, St. Louis, MO), 0.025% Tween 20 (Sigma). The compound or vehicle was administered by oral gavage in a volume of 1 mL. Two vehicle groups were used per experiment to control for intra-experiment variability, and three experiments were performed. LPS (E. coli serotype 0111:B4, Sigma) was administered two, four or six hours later by intravenous injection at a dose of 1 mg/kg in 0.5 mL sterile saline (Baxter Healthcare, Deerfield, IL). Blood was collected in serum separator tubes via cardiac puncture ninety minutes after LPS injection, a time point corresponding to maximal TNFa production (data not shown). After clotting, serum was withdrawn and stored at 20 °C until it was assayed for TNFa. TNFa levels in serum were quantified from a recombinant rat TNFa (Biosource International) standard curve using a four parameter fit generated by an Excel

S. R. Selness et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4059–4065 (Microsoft, Redmond, WA) macro. The limit of detection for the ELISA was approximately 41 pg TNFa/mL. 11. The Pfizer Institutional Animal Care and Use Committee reviewed and approved the animal use in these studies. The animal care and use program is fully accredited by the Association for Assessment and Accreditation of Laboratory Animal Care, International. 12. Compounds 2 and 3 assayed in Streptococal Cell Wall (SCW) induced arthritis in rats as follows: Arthritis was induced in female Lewis rats by a single intraperitoneal administration of peptidoglycan-polysaccaride complexes isolated from group a SCW (15 lg/g bodyweight). The SCW preparation was purchase from Lee Labs (Grayson, GA). The disease course is biphasic in which an acute inflammatory arthritis develops within days 1–3 (nonT-celldependent phase) followed by a chronic erosive arthritis (T-cell- dependent phase) developing on days 14–28. Only animals developing the acute phase were treated with compound from days 10 to 21 after SCW injection. Paw volume was measured on day 21 by using a water displacement

4065

plethysmometer. Each compound was prepared as an aqueous suspension in 0.5% methylcellulose and 0.025% Tween 20(sigma–aldrich). The compound was administered by oral gavage in a volume of 0.5 mL beginning on day 10 post-SCW injection and continuing daily until day 21. Methylcellulose/Tween 20 vehicle was used for comparison. Group size was four to eight animals per group. Two paw volumes were taken for each animal. Paw volume was measured on day 21 by using a water displacement plethysmometer. Three to four paws from each treatment group were scanned for bone density evaluation. Plasma samples were collected on day 21 for determination of compound levels. 13. Compounds 2 and 3 exhibited less than 50% at 10 lM against over 200 targets including, but not limited to, the following kinases: BTK, CDK2, AURKA, EGFR, FLT1, ERK1, mTOR, IKKb, IRAK4, JAK1, JAK2, JAK3, TYK2, VEGFR2, LCK, MEK1, p38d, p38c, ERK1, JNK, MK-2, TRKA, PDGFR, cRAF, ROCK1, ROCK2 and ZAP70. The only significant inhibition observed was for p38a and p38b.