Discovery and SAR of JTE-151: A Novel RORγ Inhibitor for Clinical Development.

A number of RORγ inhibitors have been reported over the past decade. There were also several examples advancing to human clinical trials, however, none of them has reached the market yet, suggesting that there could be common obstacles for their future development. As was expected from the general homology of nuclear receptor ligands, insufficient selectivity as well as poor physicochemical properties were identified as potential risks for a RORγ program. Based on such considerations, we conducted a SAR investigation by prioritizing drug-like properties to mitigate such potential drawbacks. After an intensive SAR exploration with strong emphasis on "drug-likeness" indices, an orally available RORγ inhibitor, JTE-151, was finally generated and was advanced to a human clinical trial. The compound was confirmed to possess highly selective profiles along with good metabolic stability, and most beneficially, no serious adverse events (SAE) and good PK profiles were observed in the human clinical trial.

Ternary crystal structure of human RORγ ligand-binding-domain, an inhibitor and corepressor peptide provides a new insight into corepressor interaction.

Retinoic acid-related orphan receptor gamma (RORγ) plays pivotal roles in autoimmune diseases by controlling the lineage of interleukin 17 (IL-17)-producing CD4+ T cells (Th17 cells). Structure-based drug design has proven fruitful in the development of inhibitors targeting the ligand binding domain (LBD) of RORγ. Here, we present the crystal structure of a novel RORγ inhibitor co-complex, in the presence of a corepressor (CoR) peptide. This ternary complex with compound T reveals the structural basis for an inhibitory mechanism different from the previously reported inverse agonist. Compared to the inverse agonist, compound T induces about 2 Šshift of helix 5 (H5) backbone and side-chain conformational changes of Met365 on H5. These conformational changes correlate to reduced CoR peptide binding to RORγ-LBD in the presence of compound T, which suggests that the shift of H5 is responsible. This crystal structure analysis will provide useful information for the development of novel and efficacious drugs for autoimmune disorders.

Ternary complex of human RORγ ligand-binding domain, inverse agonist and SMRT peptide shows a unique mechanism of corepressor recruitment.

Retinoid-related orphan receptor gamma (RORγ) directly controls the differentiation of Th17 cell and the production of interleukin-17, which plays an integral role in autoimmune diseases. To obtain insight into RORγ, we have determined the first crystal structure of a ternary complex containing RORγ ligand-binding domain (LBD) bound with a novel synthetic inhibitor and a repressor peptide, 22-mer peptide from silencing mediator of retinoic acid and thyroid hormone receptor (SMRT). Comparison of a binary complex of nonliganded (apo) RORγ-LBD with a nuclear receptor co-activator (NCoA-1) peptide has shown that our inhibitor displays a unique mechanism different from those caused by natural inhibitor, ursolic acid (UA). The compound unprecedentedly induces indirect disruption of a hydrogen bond between His479 on helix 11 (H11) and Tyr502 on H12, which is crucial for active conformation. This crystallographic study will allow us to develop novel synthetic compounds for autoimmune disease therapy.

SAR Exploration Guided by LE and Fsp(3): Discovery of a Selective and Orally Efficacious RORγ Inhibitor.

A novel series of RORγ inhibitors was identified starting with the HTS hit 1. After SAR investigation based on a prospective consideration of two drug-likeness metrics, ligand efficiency (LE) and fraction of sp(3) carbon atoms (Fsp(3)), significant improvement of metabolic stability as well as reduction of CYP inhibition was observed, which finally led to discovery of a selective and orally efficacious RORγ inhibitor 3z.

Further studies on hepatitis C virus NS5B RNA-dependent RNA polymerase inhibitors toward improved replicon cell activities: benzimidazole and structurally related compounds bearing the 2-morpholinophenyl moiety.

Following the discovery of JTK-109 (1) as a potent inhibitor of hepatitis C virus NS5B RNA-dependent RNA polymerase, [(a) Hirashima, S.; Suzuki, T.; Ishida, T.; Noji, S.; Yata, S.; Ando, I.; Komatsu, M.; Ikeda, S.; Hashimoto, H. J. Med. Chem.2006, 49, 4721. (b) Hashimoto, H.; Mizutani, K.; Yoshida, A. Int. Patent Appl. WO 01/47883, 2001.] further studies toward the improvement of the cellular potency have been performed. A greater than 40-fold improvement was achieved through replacing the biphenyl moiety with a 2-morpholinophenyl group and the benzimidazole ring with the tetracyclic scaffold to afford compound 7 with an excellent replicon potency (EC(50)=7.6 nM).

Discovery of conformationally constrained tetracyclic compounds as potent hepatitis C virus NS5B RNA polymerase inhibitors.

We report a new series of hepatitis C virus NS5B RNA polymerase inhibitors containing a conformationally constrained tetracyclic scaffold. SAR studies led to the identification of 6,7-dihydro-5H-benzo[5,6][1,4]diazepino[7,1-a]indoles (19 and 20) bearing a basic pendent group with high biochemical and cellular potencies. These compounds displayed a very small shift in cellular potency when the replicon assay was performed in the presence of human serum albumin.

Benzimidazole derivatives bearing substituted biphenyls as hepatitis C virus NS5B RNA-dependent RNA polymerase inhibitors: structure-activity relationship studies and identification of a potent and highly selective inhibitor JTK-109.

Following the discovery of a new series of benzimidazole derivatives bearing a diarylmethyl group as inhibitors of hepatitis C virus NS5B RNA-dependent RNA polymerase (HCV NS5B RdRp),1,2 we extended the structure-activity relationship (SAR) study to analogues bearing a substituted biphenyl group and succeeded in a significant advancement of activity. Starting from compound 1, optimization of the A, B, and C rings afforded potent inhibitors with low nanomolar potency against genotype 1b NS5B. The compounds, which have a substituent with a carbonyl function at the 4-position of the B-ring, efficiently blocked subgenomic viral RNA replication in the replicon cell assay at low submicromolar concentrations. Among the new compounds, compound 10n (JTK-109) exhibited favorable pharmacokinetic profiles, high selectivity for NS5B, and good safety profiles, suggesting the potential for a clinical candidate in the treatment of hepatitis C.

Benzimidazole inhibitors of hepatitis C virus NS5B polymerase: identification of 2-[(4-diarylmethoxy)phenyl]-benzimidazole.

A series of 1-cycloalkyl-2-phenyl-1H-benzimidazole-5-carboxylic acid derivatives was synthesized and evaluated for inhibitory activity against HCV NS5B RNA-dependent RNA polymerase (RdRp). A SAR study was performed and led to identify the 2-[(4-diarylmethoxy)phenyl]-benzimidazoles as potent inhibitors. They inhibit subgenomic HCV RNA replication in the replicon cells at low micromolar concentrations (EC(50) as low as 1.1microM). They are selective against DNA polymerases (IC(50)>10microM) and exhibit low cytotoxicity.

Convergent approach to pumiliotoxin alkaloids. Asymmetric total synthesis of (+)-pumiliotoxins A, B, and 225F.

A versatile convergent approach for preparing the pumiliotoxin alkaloids has been developed employing Pd(0)-catalyzed cross-coupling reactions between homoallylic organozincs and vinyl iodides. The (Z)-iodoalkylidene indolizidine 34, which served as a common key intermediate, was synthesized through highly stereoselective addition of the chiral silylallene 19 to (S)-acetylpyrrolidine followed by a palladium-catalyzed intramolecular carbonylation[bond]cyclization sequence. This synthetic process allowed the first total synthesis of (+)-pumiliotoxin 225F. The intermediate (Z)-iodoalkylidene indolizidine 34 obtained was converted to a homoallylzinc chloride derivative and subjected to homoallyl-vinyl cross-coupling with the (E)-vinyl iodide 42 using Pd(PPh(3))(4) catalyst to give the cross-coupled product 47 with a 1,5-diene side chain. Subsequent deprotection provided (+)-pumiliotoxin A. On the other hand, the (Z)-iodoalkylidene indolizidine 34 was transformed into the homoallyl-tert-butyl zinc derivative, which underwent palladium-catalyzed cross-coupling with the (E)-vinyl iodide 50 and subsequent deprotection to afford (+)-pumiliotoxin B.