The NS5A protein plays a critical role in the replication of HCV and has been the focus of numerous research efforts over the past few years. NS5A inhibitors have shown impressive in vitro potency profiles in HCV replicon assays, making them attractive components for inclusion in all oral combination regimens. Early work in the NS5A arena led to the discovery of our first clinical candidate, MK-4882 [2-((S)-pyrrolidin-2-yl)-5-(2-(4-(5-((S)-pyrrolidin-2-yl)-1H-imidazol-2-yl)phenyl)benzofuran-5-yl)-1H-imidazole]. While preclinical proof-of-concept studies in HCV-infected chimpanzees harboring chronic genotype 1 infections resulted in significant decreases in viral load after both single- and multiple-dose treatments, viral breakthrough proved to be a concern, thus necessitating the development of compounds with increased potency against a number of genotypes and NS5A resistance mutations. Modification of the MK-4882 core scaffold by introduction of a cyclic constraint afforded a series of tetracyclic inhibitors, which showed improved virologic profiles. Herein we describe the research efforts that led to the discovery of MK-8742, a tetracyclic indole-based NS5A inhibitor, which is currently in phase 2b clinical trials as part of an all-oral, interferon-free regimen for the treatment of HCV infection.

The expression of the cannabinoid peripheral cannabinoid receptor (CB 2 ) receptor on peripheral immune cells suggests that compounds specific for CB 2 might be effective anti-inflammatory agents. In this report, we present the initial biological profiling of a novel triaryl bis-sulfone, Sch.336, which is selective for the human cannabinoid CB 2 receptor (hCB 2 ). Sch.336 is an inverse agonist at hCB 2 , as shown by its ability to decrease guanosine 5Ј-3-O-(thio)triphosphate (GTP␥S) binding to membranes containing hCB 2 , by the ability of GTP␥S to left-shift Sch.336 binding to hCB 2 in these membranes, and by the compound's ability to increase forskolin-stimulated cAMP levels in CHO cells expressing hCB 2 . In these systems, Sch.336 displays a greater potency than that reported for the CB 2 In vitro, Sch.336 impairs the migration of CB 2 -expressing recombinant cell lines to the cannabinoid agonist 2-arachidonylglycerol. In vivo, the compound impairs migration of cells to cannabinoid agonist HU210 [(6aR)-trans-3-(1,1-dimethylheptyl)-6a,7,10,10a-tetrahydro-1-hydroxy-6,6-dimethyl-6H-dibenzo [b,d] pyran-9-methanol]. Oral administration of the Sch.336 significantly inhibited leukocyte trafficking in several rodent in vivo models, induced either by specific chemokines or by antigen challenge. Finally, oral administration of Sch.336 blocked ovalbumin-induced lung eosinophilia in mice, a disease model for allergic asthma. We conclude that selective cannabinoid CB 2 inverse agonists may serve as novel immunomodulatory agents in the treatment of a broad range of acute and chronic inflammatory disorders in which leukocyte recruitment is a hallmark of disease pathology.The identification of a second cannabinoid receptor present primarily in peripheral immune tissues and cells (Munro et al., 1993) suggested an immunomodulatory role for endocannabinoids independent of the effects mediated by their interaction with the "brain" cannabinoid CB 1 receptor. Libraries of selective compounds now exist, based either on the structure of known ligands for the cannabinoid receptors or on results of random compound library screening (Huffman, 2000). With the help of CB 2 -specific compounds and by characterization of a CB 2 Ϫ/Ϫ mouse strain (Buckley et al., 2000), Article, publication date, and citation information can be found at

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The KCNN4 potassium-ion channel has been reported to play an important role in regulating antigen-induced T cell effector functions in vitro. This study presents the first evidence that a selective KCNN4 blocker, TRAM-34, confers protection against experimental autoimmune encephalomyelitis (EAE) in the mouse model. Treatment with the KCNN4 blocker did not prevent infiltration of T cells in the spinal cord, but resulted in the reduction of both the protein and the message levels of TNF-a and IFN-c as well as the message levels of several other pro-inflammatory molecules in the spinal cord. Plasma concentrations of TRAM-34 within a 24-h period were between the in vitro IC 50 and IC 90 values for the KCNN4 channel. The effect of TRAM-34 was reversible, as indicated by the development of clinical EAE symptoms within 48 h after withdrawal of treatment. In summary, our data support the idea that KCNN4 channels play a critical role in the immune response during the development of MOG-induced EAE in C57BL/6 mice.See accompanying Commentary: http://dx

Background: CCR2 plays a key role in regulating monocyte trafficking to sites of inflammation and therefore has been the focus of much interest as a target for inflammatory disease.