Asitha Abeywardane

Synthesis, SAR, and series evolution of novel oxadiazole-containing 5-lipoxygenase activating protein inhibitors: discovery of 2-[4-(3-{(r)-1-[4-(2-amino-pyrimidin-5-yl)-phenyl]-1-cyclopropyl-ethyl}-[1,2,4]oxadiazol-5-yl)-pyrazol-1-yl]-N,N-dimethyl-acetamide (BI 665915).

The synthesis, structure-activity relationship (SAR), and evolution of a novel series of oxadiazole-containing 5-lipoxygenase-activating protein (FLAP) inhibitors are described. The use of structure-guided drug design techniques provided compounds that demonstrated excellent FLAP binding potency (IC50 < 10 nM) and potent inhibition of LTB4 synthesis in human whole blood (IC50 < 100 nM). Optimization of binding and functional potencies, as well as physicochemical properties resulted in the identification of compound 69 (BI 665915) that demonstrated an excellent cross-species drug metabolism and pharmacokinetics (DMPK) profile and was predicted to have low human clearance. In addition, 69 was predicted to have a low risk for potential drug-drug interactions due to its cytochrome P450 3A4 profile. In a murine ex vivo whole blood study, 69 demonstrated a linear dose-exposure relationship and a dose-dependent inhibition of LTB4 production.

Discovery of Potent, Selective Chymase Inhibitors via Fragment Linking Strategies

Chymase plays an important and diverse role in the homeostasis of a number of cardiovascular processes. Herein, we describe the identification of potent, selective chymase inhibitors, developed using fragment-based, structure-guided linking and optimization techniques. High-concentration biophysical screening methods followed by high-throughput crystallography identified an oxindole fragment bound to the S1 pocket of the protein exhibiting a novel interaction pattern hitherto not observed in chymase inhibitors. X-ray crystallographic structures were used to guide the elaboration/linking of the fragment, ultimately leading to a potent inhibitor that was >100-fold selective over cathepsin G and that mitigated a number of liabilities associated with poor physicochemical properties of the series it was derived from.

Integrated strategies for identifying leads that target the NS3 helicase of the hepatitis C virus.

Future treatments for individuals infected by the hepatitis C virus (HCV) will likely involve combinations of compounds that inhibit multiple viral targets. The helicase of HCV is an attractive target with no known drug candidates in clinical trials. Herein we describe an integrated strategy for identifying fragment inhibitors using structural and biophysical techniques. Based on an X-ray structure of apo HCV helicase and in silico and bioinformatic analyses of HCV variants, we identified that one site in particular (labeled 3 + 4) was the most conserved and attractive pocket to target for a drug discovery campaign. Compounds from multiple sources were screened to identify inhibitors or binders to this site, and enzymatic and biophysical assays (NMR and SPR) were used to triage the most promising ligands for 3D structure determination by X-ray crystallography. Medicinal chemistry and biophysical evaluations focused on exploring the most promising lead series. The strategies employed here can have general utility in drug discovery.

N-Arylsulfonyl-α-amino carboxamides are potent and selective inhibitors of the chemokine receptor CCR10 that show efficacy in the murine DNFB model of contact hypersensitivity

Compound 1 ((4-amino-3,5-dichlorophenyl)-1-(4-methylpiperidin-1-yl)-4-(2-nitroimidazol-1-yl)-1-oxobutane-2-sulfonamido) was discovered to be a 690nM antagonist of human CCR10 Ca2+ flux. Optimization delivered (2R)-4-(2-cyanopyrrol-1-yl)-S-(1H-indol-4-yl)-1-(4-methylpiperidin-1-yl)-1-oxobutane-2-sulfonamido (eut-22) that is 300 fold more potent a CCR10 antagonist than 1 and eliminates potential toxicity, mutagenicity, and drug-drug-interaction liabilities often associated with nitroaryls and anilines. eut-22 is highly selective over other GPCRs, including a number of other chemokine receptors. Finally, eut-22 is efficacious in the murine DNFB model of contact hypersensitivity. The efficacy of this compound provides further evidence for the role of CCR10 in dermatological inflammatory conditions.

Discovery and optimization of oxadiazole-based FLAP inhibitors

Structure activity relationship (SAR) investigation of an oxadiazole based series led to the discovery of several potent FLAP inhibitors. Lead optimization focused on achieving functional activity while improving physiochemical properties and reducing hERG inhibition. Several compounds with favorable in vitro and in vivo properties were identified that were suitable for advanced profiling.