Discovery of BIIB068: A Selective, Potent, Reversible Bruton's Tyrosine Kinase Inhibitor as an Orally Efficacious Agent for Autoimmune Diseases.

Autoreactive B cell-derived antibodies form immune complexes that likely play a pathogenic role in autoimmune diseases. In systemic lupus erythematosus (SLE), these antibodies bind Fc receptors on myeloid cells and induce proinflammatory cytokine production by monocytes and NETosis by neutrophils. Bruton's tyrosine kinase (BTK) is a non-receptor tyrosine kinase that signals downstream of Fc receptors and plays a transduction role in antibody expression following B cell activation. Given the roles of BTK in both the production and sensing of autoreactive antibodies, inhibitors of BTK kinase activity may provide therapeutic value to patients suffering from autoantibody-driven immune disorders. Starting from an in-house proprietary screening hit followed by structure-based rational design, we have identified a potent, reversible BTK inhibitor, BIIB068 (1), which demonstrated good kinome selectivity with good overall drug-like properties for oral dosing, was well tolerated across preclinical species at pharmacologically relevant doses with good ADME properties, and achieved >90% inhibition of BTK phosphorylation (pBTK) in humans.

E7449: A dual inhibitor of PARP1/2 and tankyrase1/2 inhibits growth of DNA repair deficient tumors and antagonizes Wnt signaling.

Inhibition of Poly(ADP-ribose) Polymerase1 (PARP1) impairs DNA damage repair, and early generation PARP1/2 inhibitors (olaparib, niraparib, etc.) have demonstrated clinical proof of concept for cancer treatment. Here, we describe the development of the novel PARP inhibitor E7449, a potent PARP1/2 inhibitor that also inhibits PARP5a/5b, otherwise known as tankyrase1 and 2 (TNKS1 and 2), important regulators of canonical Wnt/ß-catenin signaling. E7449 inhibits PARP enzymatic activity and additionally traps PARP1 onto damaged DNA; a mechanism previously shown to augment cytotoxicity. Cells deficient in DNA repair pathways beyond homologous recombination were sensitive to E7449 treatment. Chemotherapy was potentiated by E7449 and single agent had significant antitumor activity in BRCA-deficient xenografts. Additionally, E7449 inhibited Wnt/ß-catenin signaling in colon cancer cell lines, likely through TNKS inhibition. Consistent with this possibility, E7449 stabilized axin and TNKS proteins resulting in ß-catenin de-stabilization and significantly altered expression of Wnt target genes. Notably, hair growth mediated by Wnt signaling was inhibited by E7449. A pharmacodynamic effect of E7449 on Wnt target genes was observed in tumors, although E7449 lacked single agent antitumor activity in vivo, a finding typical for selective TNKS inhibitors. E7449 antitumor activity was increased through combination with MEK inhibition. Particularly noteworthy was the lack of toxicity, most significantly the lack of intestinal toxicity reported for other TNKS inhibitors. E7449 represents a novel dual PARP1/2 and TNKS1/2 inhibitor which has the advantage of targeting Wnt/ß-catenin signaling addicted tumors. E7449 is currently in early clinical development.

A Baeyer-Villiger oxidation specifically catalyzed by human flavin-containing monooxygenase 5.

10-((4-Hydroxypiperidin-1-yl)methyl)chromeno[4,3,2-de]phthalazin-3(2H)-one (E7016), an inhibitor of poly(ADP-ribose) polymerase, is being developed for anticancer therapy. One of the major metabolites identified in preclinical animal studies was the product of an apparent oxidation and ring opening of the 4-hydroxypiperidine. In vitro, this oxidized metabolite could not be generated by incubating E7016 with animal or human liver microsomes. Further studies revealed the formation of this unique metabolite in hepatocytes. In a NAD(P)(+)-dependent manner, this metabolite was also generated by liver S9 fractions and recombinant human flavin-containing monooxygenase (FMO) 5 that was fortified with liver cytosol fractions. In animal and human liver S9, this metabolic pathway could be inhibited by 4-methylpyrazole, bis-p-nitrophenylphosphate (BNPP), or a brief heat treatment at 50°C. Based on these results, the overall metabolic pathway was believed to involve a two-step oxidation process: dehydrogenation of the secondary alcohol in liver cytosol followed by an FMO5-mediated Baeyer-Villiger oxidation in liver microsomes. The two oxidation steps were coupled via regeneration of NAD(P)(+) and NAD(P)H. To further confirm this mechanism, the proposed ketone intermediate was independently synthesized. In an NAD(P)H-dependent manner, the synthetic ketone intermediate was metabolized to the same ring-opened metabolite in animal and human liver microsomes. This metabolic reaction was also inhibited by BNPP or a brief heat treatment at 50°C. Methimazole, the substrate/inhibitor of FMO1 and FMO3, did not inhibit this reaction. The specificity of FMO5 toward catalyzing this Baeyer-Villiger oxidation was further demonstrated by incubating the synthetic ketone intermediate in recombinant enzymes.

Discovery of a potent, orally active 11beta-hydroxysteroid dehydrogenase type 1 inhibitor for clinical study: identification of (S)-2-((1S,2S,4R)-bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221).

Thiazolones with an exo-norbornylamine at the 2-position and an isopropyl group on the 5-position are potent 11beta-HSD1 inhibitors. However, the C-5 center was prone to epimerization in vitro and in vivo, forming a less potent diastereomer. A methyl group was added to the C-5 position to eliminate epimerization, leading to the discovery of (S)-2-((1S,2S,4R)-bicyclo[2.2.1]heptan-2-ylamino)-5-isopropyl-5-methylthiazol-4(5H)-one (AMG 221). This compound decreased fed blood glucose and insulin levels and reduced body weight in diet-induced obesity mice.

Effects of solvent on chiral and enantiomeric separation of Koga bases using derivatized amylose chiral stationary phase.

The separation of R,R-, S,S-, and meso-Koga bases on derivatized amylose chiral stationary phases (CSP) has been studied using different alcohol and alcohol-hexane mixtures as eluant. Straight-chain and branched alcohols with carbon numbers from one to four were investigated. The carbon number and geometry of the alcohol impacts the separation of Koga bases. The optimal separations were obtained using a mixture of methanol with linear or branched alcohol. Also, the elution order of meso- and R,R-Koga base was switched as content of branched alcohol increases in cosolvent. The study of acidic and basic additive effects demonstrated that maintaining analytes in the free base state is crucial in order to achieve retention and separation. TEA alone or TEA and TFA mixture were used in the studies.

An aldol-based synthesis of (+)-peloruside a, a potent microtubule stabilizing agent.

A convergent synthesis of the marine natural product (+)-peloruside has been reported. This target has been assembled through the successive application of two methyl ketone boron aldol addition reactions to the latent C(7)-C(11) dialdehyde synthon. This approach afforded a 22-step synthesis of this natural product. The influence of resident stereocenters on aldol reaction diastereoselection has been examined in detail.

2-amino-1,3-thiazol-4(5H)-ones as potent and selective 11beta-hydroxysteroid dehydrogenase type 1 inhibitors: enzyme-ligand co-crystal structure and demonstration of pharmacodynamic effects in C57Bl/6 mice.

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has attracted considerable attention during the past few years as a potential target for the treatment of diseases associated with metabolic syndrome. In our ongoing work on 11beta-HSD1 inhibitors, a series of new 2-amino-1,3-thiazol-4(5 H)-ones were explored. By inserting various cycloalkylamines at the 2-position and alkyl groups or spirocycloalkyl groups at the 5-position of the thiazolone, several potent 11beta-HSD1 inhibitors were identified. An X-ray cocrystal structure of human 11beta-HSD1 with compound 6d (Ki=28 nM) revealed a large lipophilic pocket accessible by substitution off the 2-position of the thiazolone. To increase potency, analogues were prepared with larger lipophilic groups at this position. One of these compounds, the 3-noradamantyl analogue 8b, was a potent inhibitor of human 11beta-HSD1 (Ki=3 nM) and also inhibited 11beta-HSD1 activity in lean C57Bl/6 mice when evaluated in an ex vivo adipose and liver cortisone to cortisol conversion assay.

The discovery of 2-anilinothiazolones as 11beta-HSD1 inhibitors.

A series of 2-anilinothiazolones were prepared as inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). The most potent compounds contained a 2-chloro or 2-fluoro group on the aniline ring with an isopropyl substituent on the 5-position of the thiazolone ring (compounds 2 and 3, respectively). The binding mode was determined through the X-ray co-crystal structure of the enzyme with compound 3. This compound was also approximately 70-fold selective over 11beta-HSD2 and was orally bioavailable in rat pharmacokinetic studies. However, compound 3 was >580-fold less active in the 11beta-HSD1 cell assay when tested in the presence of 3% human serum albumin.