Discovery of Selective and Orally Bioavailable Protein Kinase Cθ (PKCθ) Inhibitors from a Fragment Hit

Abstract

Protein kinase Cθ (PKCθ) regulates a key step in the activation of T cells. On the basis of its mechanism of action, inhibition of this kinase is hypothesized to serve as an effective therapy for autoimmune diseases such as rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and psoriasis. Herein, the discovery of a small molecule PKCθ inhibitor is described, starting from a fragment hit 1 and advancing to compound 41 through the use of structure-based drug design. Compound 41 demonstrates excellent in vitro activity, good oral pharmacokinetics, and efficacy in both an acute in vivo mechanistic model and a chronic in vivo disease model but suffers from tolerability issues upon chronic dosing.

Optimized Protein Kinase Cθ (PKCθ) Inhibitors Reveal Only Modest Anti-inflammatory Efficacy in a Rodent Model of Arthritis

“…TLC: R f = 0.70 (eluting with 10% EtOAc in petroleum ether). 1 (R)-6-((3R,4R)-1,3-Dimethylpiperidin-4-yl)-7-(2-fluorophenyl)-4-methyl-2,10-dihydro-9-oxa-1,2,4a-triazaphenanthren-3-one Hydrochloride (17a).…”

“…The residue was purified by column chromatography on silica gel (eluting with 5−10% EtOAc in petroleum ether) to give (R)-2-(6-bromo-3-oxo-2,3-dihydrobenzo [1,4] Step C. A solution of (R)-2-(6-bromo-3-oxo-2,3-dihydrobenzo- [1,4]oxazin-4-yl)propionic acid ethyl ester (82.4 g, 252 mmol) and Lawesson reagent (61.1 g, 151 mmol) in toluene (900 mL) was heated at reflux for 3 h and then cooled to ambient temperature. The solvent was removed in vacuo, and the residue was purified by chromatography on silica gel (eluting with 5−10% EtOAc in petroleum ether) to give (R)-2-(6-bromo-3-thioxo-2,3-dihydrobenzo- [1,4] Step D. To a mixture of (R)-2-(6-bromo-3-thioxo-2,3-dihydrobenzo [1,4]oxazin-4-yl)propionic acid ethyl ester (75.2 g, 219 mmol) in EtOH (800 mL) was added hydrazine hydrate (98%, 21.9 g, 438 mmol), and the reaction mixture was stirred at ambient temperature overnight. The precipitate was collected by filtration and washed with cold EtOH (3 × 80 mL) to give 6-bromo-4-methyl-2,10-dihydro-9-oxa-1,2,4a-triazaphenanthren-3-one (6 g, 9%) as a yellow solid.…”

“…Alkylation of functionalized benzo [1,4]oxazinones 2a−c with (S)-2-trifluoromethanesulfonyloxypropionic acid ethyl ester [generated by treatment of (S)-ethyl lactate with triflic anhydride] gave 3a−c. Conversion to benzo [1,4]oxazinethiones 4a−c by treatment with Lawesson reagent and subsequent cyclization with hydrazine hydrate afforded versatile triazinone intermediates 5a−c. Bromide 5b could be further transformed to the boronate ester (R 1 = pinacolatoboron, R 2 = H, 5d) by treatment with bispinacolato(diboron).…”

Synthesis of furo[2',3':4,5]pyrrolo[1,2-d][1,2,4]triazine derivatives and their antibacterial activity

“…Heterocyclic compounds containing five-and six-membered nitrogen heterocyclic rings have also attracted the attention due to the fact that they exhibit many biological interactions 9,10 . In addition, 1,2,4-triazin-6-one is structural system found in numerous natural and synthetic biologically active compounds with a wide range of biological activities including anti-inflammatory, 11 antifungal, 10 antiviral, 12 anti-HIV 13 or anticonvulsant. 14 Among tricyclic 5-5-6 fused ring heterocycles only thieno [3,2-b]pyrrole [3,2- 16 have been synthesized and only these thieno-derivatives were evaluated for their anticancer activity.…”

NMR spectroscopic properties of furo[2′,3′:4,5]pyrrolo[1,2-d][1,2,4]triazine derivatives

“…Heterocyclic compounds containing fiveand six-membered nitrogen heterocyclic rings have also attracted the attention due to the fact that they exhibit many biological interactions (Astakhina et al 2016). In addition, 1,2,4-triazin-6-one is structural system found in numerous natural and synthetic biologically active compounds with a wide range of biological activity including antiinflammatory (George et al 2015) or anticonvulsant (El-Gendy et al 2008). We have recently reported the synthesis of furo [2',3':4,5]pyrrolo [1,2-d] [1,2,4]triazin-8(7H)-ones with interesting antibacterial activity (Zemanová et al 2017), but more complex spectroscopic studies were realised only on benzothieno[3,2-d]-1,2,3-triazines (Lauria et al 2014) or 7-aryl-7H-pyrazolo[3,4-d]- [1,2,3]triazin-4-ols (Khutova et al 2012).…”