Blocking NS3-NS4B interaction inhibits dengue virus in non-human primates.

Dengue is a major health threat and the number of symptomatic infections caused by the four dengue serotypes is estimated to be 96 million1 with annually around 10,000 deaths2. However, no antiviral drugs are available for the treatment or prophylaxis of dengue. We recently described the interaction between non-structural proteins NS3 and NS4B as a promising target for the development of pan-serotype dengue virus (DENV) inhibitors3. Here we present JNJ-1802-a highly potent DENV inhibitor that blocks the NS3-NS4B interaction within the viral replication complex. JNJ-1802 exerts picomolar to low nanomolar in vitro antiviral activity, a high barrier to resistance and potent in vivo efficacy in mice against infection with any of the four DENV serotypes. Finally, we demonstrate that the small-molecule inhibitor JNJ-1802 is highly effective against viral infection with DENV-1 or DENV-2 in non-human primates. JNJ-1802 has successfully completed a phase I first-in-human clinical study in healthy volunteers and was found to be safe and well tolerated4. These findings support the further clinical development of JNJ-1802, a first-in-class antiviral agent against dengue, which is now progressing in clinical studies for the prevention and treatment of dengue.

A pan-serotype dengue virus inhibitor targeting the NS3-NS4B interaction.

Dengue virus causes approximately 96 million symptomatic infections annually, manifesting as dengue fever or occasionally as severe dengue1,2. There are no antiviral agents available to prevent or treat dengue. Here, we describe a highly potent dengue virus inhibitor (JNJ-A07) that exerts nanomolar to picomolar activity against a panel of 21 clinical isolates that represent the natural genetic diversity of known genotypes and serotypes. The molecule has a high barrier to resistance and prevents the formation of the viral replication complex by blocking the interaction between two viral proteins (NS3 and NS4B), thus revealing a previously undescribed mechanism of antiviral action. JNJ-A07 has a favourable pharmacokinetic profile that results in outstanding efficacy against dengue virus infection in mouse infection models. Delaying start of treatment until peak viraemia results in a rapid and significant reduction in viral load. An analogue is currently in further development.

Molecular mechanism of respiratory syncytial virus fusion inhibitors.

Respiratory syncytial virus (RSV) is a leading cause of pneumonia and bronchiolitis in young children and the elderly. Therapeutic small molecules have been developed that bind the RSV F glycoprotein and inhibit membrane fusion, yet their binding sites and molecular mechanisms of action remain largely unknown. Here we show that these inhibitors bind to a three-fold-symmetric pocket within the central cavity of the metastable prefusion conformation of RSV F. Inhibitor binding stabilizes this conformation by tethering two regions that must undergo a structural rearrangement to facilitate membrane fusion. Inhibitor-escape mutations occur in residues that directly contact the inhibitors or are involved in the conformational rearrangements required to accommodate inhibitor binding. Resistant viruses do not propagate as well as wild-type RSV in vitro, indicating a fitness cost for inhibitor escape. Collectively, these findings provide new insight into class I viral fusion proteins and should facilitate development of optimal RSV fusion inhibitors.

Design and synthesis of tetrahydropyridopyrimidine based Toll-Like Receptor (TLR) 7/8 dual agonists.

In a continuing effort to discover novel TLR agonists, herein we report on the discovery and structure-activity relationship of novel tetrahydropyridopyrimidine TLR 7/8 agonists. Optimization of this series towards dual agonist activity and a high clearance profile resulted in the identification of compound 52a1. Evaluation in vivo revealed an interferon stimulated response (ISG) in mice with limited systemic exposure and demonstrated the potential in antiviral treatment or as a vaccine adjuvant.

Discovery of selective 2,4-diaminoquinazoline toll-like receptor 7 (TLR 7) agonists.

The discovery of a novel series of highly potent quinazoline TLR 7/8 agonists is described. The synthesis and structure-activity relationship is presented. Structural requirements and optimization of this series toward TLR 7 selectivity afforded the potent agonist 48. Pharmacokinetic and pharmacodynamic studies highlighted 48 as an orally available endogenous interferon (IFN-α) inducer in mice.

Discovery of JNJ-1802, a First-in-Class Pan-Serotype Dengue Virus NS4B Inhibitor.

Dengue is a global public health threat, with about half of the world's population at risk of contracting this mosquito-borne viral disease. Climate change, urbanization, and global travel accelerate the spread of dengue virus (DENV) to new areas, including southern parts of Europe and the US. Currently, no dengue-specific small-molecule antiviral for prophylaxis or treatment is available. Here, we report the discovery of JNJ-1802 as a potent, pan-serotype DENV inhibitor (EC50's ranging from 0.057 to 11 nM against the four DENV serotypes). The observed oral bioavailability of JNJ-1802 across preclinical species, its low clearance in human hepatocytes, the absence of major in vitro pharmacology safety alerts, and a dose-proportional increase in efficacy against DENV-2 infection in mice were all supportive of its selection as a development candidate against dengue. JNJ-1802 is being progressed in clinical studies for the prevention or treatment of dengue.

Spiro-Azetidine Oxindoles as Long-Acting Injectables for Pre-Exposure Prophylaxis against Respiratory Syncytial Virus Infections.

Respiratory syncytial virus (RSV) is a major cause of hospitalization in infants, the elderly, and immune-compromised patients. While a half-life extended monoclonal antibody and 2 vaccines have recently been approved for infants and the elderly, respectively, options to prevent disease in immune-compromised patients are still needed. Here, we describe spiro-azetidine oxindoles as small molecule RSV entry inhibitors displaying favorable potency, developability attributes, and long-acting PK when injected as an aqueous suspension, suggesting their potential to prevent complications following RSV infection over a period of 3 to 6 months with 1 or 2 long-acting intramuscular (IM) or subcutaneous (SC) injections in these immune-compromised patients.

Discovery of Acyl-Indole Derivatives as Pan-Serotype Dengue Virus NS4B Inhibitors.

In the absence of any approved dengue-specific treatment, the discovery and development of a novel small-molecule antiviral for the prevention or treatment of dengue are critical. We previously reported the identification of a novel series of 3-acyl-indole derivatives as potent and pan-serotype dengue virus inhibitors. We herein describe our optimization efforts toward preclinical candidates 24a and 28a with improved pan-serotype coverage (EC50's against the four DENV serotypes ranging from 0.0011 to 0.24 µM for 24a and from 0.00060 to 0.084 µM for 28a), chiral stability, and oral bioavailability in preclinical species, as well as showing a dose-proportional increase in efficacy against DENV-2 infection in vivo in mice.

Structural and mechanistic insights into the inhibition of respiratory syncytial virus polymerase by a non-nucleoside inhibitor.

The respiratory syncytial virus polymerase complex, consisting of the polymerase (L) and phosphoprotein (P), catalyzes nucleotide polymerization, cap addition, and cap methylation via the RNA dependent RNA polymerase, capping, and Methyltransferase domains on L. Several nucleoside and non-nucleoside inhibitors have been reported to inhibit this polymerase complex, but the structural details of the exact inhibitor-polymerase interactions have been lacking. Here, we report a non-nucleoside inhibitor JNJ-8003 with sub-nanomolar inhibition potency in both antiviral and polymerase assays. Our 2.9 Å resolution cryo-EM structure revealed that JNJ-8003 binds to an induced-fit pocket on the capping domain, with multiple interactions consistent with its tight binding and resistance mutation profile. The minigenome and gel-based de novo RNA synthesis and primer extension assays demonstrated that JNJ-8003 inhibited nucleotide polymerization at the early stages of RNA transcription and replication. Our results support that JNJ-8003 binding modulates a functional interplay between the capping and RdRp domains, and this molecular insight could accelerate the design of broad-spectrum antiviral drugs.

Benzoxazole and benzothiazole amides as novel pharmacokinetic enhancers of HIV protease inhibitors.

A new class of benzoxazole and benzothiazole amide derivatives exhibiting potent CYP3A4 inhibiting properties was identified. Extensive lead optimization was aimed at improving the CYP3A4 inhibitory properties as well as overall ADME profile of these amide derivatives. This led to the identification of thiazol-5-ylmethyl (2S,3R)-4-(2-(ethyl(methyl)amino)-N-isobutylbenzo[d]oxazole-6-carboxamido)-3-hydroxy-1-phenylbutan-2-ylcarbamate (C1) as a lead candidate for this class. This compound together with structurally similar analogues demonstrated excellent 'boosting' properties when tested in dogs. These findings warrant further evaluation of their properties in an effort to identify valuable alternatives to Ritonavir as pharmacokinetic enhancers.

Discovery of 4'-azido-2'-deoxy-2'-C-methyl cytidine and prodrugs thereof: a potent inhibitor of Hepatitis C virus replication.

4'-Azido-2'-deoxy-2'-methylcytidine (14) is a potent nucleoside inhibitor of the HCV NS5B RNA-dependent RNA polymerase, displaying an EC(50) value of 1.2 µM and showing moderate in vivo bioavailability in rat (F=14%). Here we describe the synthesis and biological evaluation of 4'-azido-2'-deoxy-2'-methylcytidine and prodrug derivatives thereof.

From Oxetane to Thietane: Extending the Antiviral Spectrum of 2'-Spirocyclic Uridines by Substituting Oxygen with Sulfur.

In continuation of our efforts of finding novel nucleoside inhibitors for the treatment of viral diseases, we initiated a discovery research program aimed at identifying novel nucleos(t)ide inhibitors for emerging diseases like Dengue and Chikungunya. Based on the previously reported 2'-spiro-oxetane uridine derivatives active against Hepatitis C Virus (HCV), we envisaged its sulfur analogue as an interesting congener both from a synthetic as well as biological point of view. Surprisingly, we found the 2'-spirothietane uridine derivatives not only to be active against HCV and Dengue virus (DENV), viruses belonging to the flavivirus family, but also to demonstrate activity against alphaviruses like Chikungunya virus (CHIKV) and Sindbis virus (SINV).

TMC310911, a novel human immunodeficiency virus type 1 protease inhibitor, shows in vitro an improved resistance profile and higher genetic barrier to resistance compared with current protease inhibitors.

TMC310911 is a novel human immunodeficiency virus type 1 (HIV-1) protease inhibitor (PI) structurally closely related to darunavir (DRV) but with improved virological characteristics. TMC310911 has potent activity against wild-type (WT) HIV-1 (median 50% effective concentration [EC(50)], 14 nM) and a wide spectrum of recombinant HIV-1 clinical isolates, including multiple-PI-resistant strains with decreased susceptibility to currently approved PIs (fold change [FC] in EC(50), >10). For a panel of 2,011 recombinant clinical isolates with decreased susceptibility to at least one of the currently approved PIs, the FC in TMC310911 EC(50) was ≤ 4 for 82% of isolates and ≤ 10 for 96% of isolates. The FC in TMC310911 EC(50) was ≤ 4 and ≤ 10 for 72% and 94% of isolates with decreased susceptibility to DRV, respectively. In vitro resistance selection (IVRS) experiments with WT virus and TMC310911 selected for mutations R41G or R41E, but selection of resistant virus required a longer time than IVRS performed with WT virus and DRV. IVRS performed with r13025, a multiple-PI-resistant recombinant clinical isolate, and TMC310911 selected for mutations L10F, I47V, and L90M (FC in TMC310911 EC(50) = 16). IVRS performed with r13025 in the presence of DRV required less time and resulted in more PI resistance-associated mutations (V32I, I50V, G73S, L76V, and V82I; FC in DRV EC(50) = 258). The activity against a comprehensive panel of PI-resistant mutants and the limited in vitro selection of resistant viruses under drug pressure suggest that TMC310911 represents a potential drug candidate for the management of HIV-1 infection for a broad range of patients, including those with multiple PI resistance.

Antiviral activity and mode of action of TMC647078, a novel nucleoside inhibitor of the hepatitis C virus NS5B polymerase.

Chronic infection with hepatitis C virus (HCV) is a major global health burden and is associated with an increased risk of liver cirrhosis and hepatocellular carcinoma. Current therapy for HCV infection has limited efficacy, particularly against genotype 1 virus, and is hampered by a range of adverse effects. Therefore, there is a clear unmet medical need for efficacious and safe direct antiviral drugs for use in combination with current treatments to increase cure rates and shorten treatment times. The broad genotypic coverage achievable with nucleosides or nucleotides and the high genetic barrier to resistance of these compounds observed in vitro and in vivo suggest that this class of inhibitors could be a valuable component of future therapeutic regimens. Here, we report the in vitro inhibitory activity and mode of action of 2'-deoxy-2'-spirocyclopropylcytidine (TMC647078), a novel and potent nucleoside inhibitor of the HCV NS5B RNA-dependent RNA polymerase that causes chain termination of the nascent HCV RNA chain. In vitro combination studies with a protease inhibitor resulted in additive efficacy in the suppression of HCV RNA replication, highlighting the potential for the combination of these two classes in the treatment of chronic HCV infection. No cytotoxic effects were observed in various cell lines. Biochemical studies indicated that TMC647078 is phosphorylated mainly by deoxycytidine kinase (dCK) without inhibiting the phosphorylation of the natural substrate, and high levels of triphosphate were observed in Huh7 cells and in primary hepatocytes in vitro. TMC647078 is a potent novel nucleoside inhibitor of HCV replication with a promising in vitro virology and biology profile.

Practical synthesis of (2'R)-2'-deoxy-2'-C-methyluridine by highly diastereoselective homogeneous hydrogenation.

Diastereoselective hydrogenation of 2'-deoxy-2'-exo-methyleneuridine was carried out under homogeneous conditions using a low loading of a chiral Rh catalyst. This, coupled with improvements in the synthesis of the substrate, allowed the smooth pilot plant preparation of the title compound on >10 kg scale.

Discovery of 3-({5-Chloro-1-[3-(methylsulfonyl)propyl]-1H-indol-2-yl}methyl)-1-(2,2,2-trifluoroethyl)-1,3-dihydro-2H-imidazo[4,5-c]pyridin-2-one (JNJ-53718678), a Potent and Orally Bioavailable Fusion Inhibitor of Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) is a seasonal virus that infects the lungs and airways of 64 million children and adults every year. It is a major cause of acute lower respiratory tract infection and is associated with significant morbidity and mortality. Despite the large medical and economic burden, treatment options for RSV-associated bronchiolitis and pneumonia are limited and mainly consist of supportive care. This publication covers the medicinal chemistry efforts resulting in the identification of JNJ-53718678, an orally bioavailable RSV inhibitor that was shown to be efficacious in a phase 2a challenge study in healthy adult subjects and that is currently being evaluated in hospitalized infants and adults. Cocrystal structures of several new derivatives helped in rationalizing some of the structure-activity relationship (SAR) trends observed.

Design, Synthesis, and Biological Evaluation of Novel Indoles Targeting the Influenza PB2 Cap Binding Region.

In the search for novel influenza inhibitors we evaluated 7-fluoro-substituted indoles as bioisosteric replacements for the 7-azaindole scaffold of Pimodivir, a PB2 (polymerase basic protein 2) inhibitor currently in clinical development. Specifically, a 5,7-difluoroindole derivative 11a was identified as a potent and metabolically stable influenza inhibitor. 11a demonstrated a favorable oral pharmacokinetic profile and in vivo efficacy in mice. In addition, it was found that 11a was not at risk of metabolism via aldehyde oxidase, an advantage over previously described inhibitors of this class. The crystal structure of 11a bound to influenza A PB2 cap region is disclosed here and deposited to the PDB.

A small-molecule fusion inhibitor of influenza virus is orally active in mice.

Recent characterization of broadly neutralizing antibodies (bnAbs) against influenza virus identified the conserved hemagglutinin (HA) stem as a target for development of universal vaccines and therapeutics. Although several stem bnAbs are being evaluated in clinical trials, antibodies are generally unsuited for oral delivery. Guided by structural knowledge of the interactions and mechanism of anti-stem bnAb CR6261, we selected and optimized small molecules that mimic the bnAb functionality. Our lead compound neutralizes influenza A group 1 viruses by inhibiting HA-mediated fusion in vitro, protects mice against lethal and sublethal influenza challenge after oral administration, and effectively neutralizes virus infection in reconstituted three-dimensional cell culture of fully differentiated human bronchial epithelial cells. Cocrystal structures with H1 and H5 HAs reveal that the lead compound recapitulates the bnAb hotspot interactions.

Dog model with implanted pump to test boosters for antiretroviral medication.

A dog model was developed to test the capacity of boosters for antiretroviral medication. Two dogs were implanted with a modified constant-flow Codman 3000 infusion pump, adapted to release viscous solutions of darunavir (TMC114) at a constant rate of 25mg/dog/day in the venous blood stream. Booster candidates were given by oral gavage for at least 4 days up to maximum 7 days in cross-over fashion, separated by a wash-out period of minimum 1 week. The booster candidates were tested at doses of 20 and/or 40mg/kg/day: blood sampling for determination of the boosting effect was performed on the last day of booster administration. The model allowed to (1) compare the boosting ratio of these booster candidates based on the exposure (determination of the area under the curve (AUC) of darunavir in presence versus absence of the booster candidate), (2) detect delay in boosting activity by evaluation of the shift of Cmax of darunavir following booster administration versus the Cmax of the booster candidate) and (3) calculate the intrinsic booster capacity, by correcting for the systemic exposure of booster candidate by normalizing the booster ratio for the booster's AUC. The latter parameter (intrinsic booster capacity) allows to determine the booster's metabolic contribution in inhibiting the metabolism of antiretroviral medication (most likely via inhibition of CYP3A4), minimizing the impact of potential effects of the booster at the level of the gastro-intestinal tract.