Molecular design and evaluation of aza-polycyclic carbamoyl pyridones as HIV-1 integrase strand transfer inhibitors.

Integrase strand transfer inhibitors (INSTIs) are the most prescribed anchor drug in antiretroviral therapy. Today, there is an increasing need for long-acting treatment of HIV-1 infection. Improving drug pharmacokinetics and anti-HIV-1 activity are key to developing more robust inhibitors suitable for long-acting formulations, but 2nd-generation INSTIs have chiral centers, making it difficult to conduct further exploration.

Discovery of tricyclic HIV-1 integrase-LEDGF/p75 allosteric inhibitors by intramolecular direct arylation reaction.

We have been conducting exploratory research to develop human immunodeficiency virus type-1 (HIV-1) integrase-LEDGF/p75 allosteric inhibitors (INLAIs). Here, we report on a newly designed compound with a tricyclic scaffold that shows promise as an inhibitor. Various scaffolds were synthesized by intramolecular direct arylation reaction to fix the position of a lipophilic side chain required for antiviral activity.

Discovery of novel HIV-1 integrase-LEDGF/p75 allosteric inhibitors based on a pyridine scaffold forming an intramolecular hydrogen bond.

We have discovered HIV-1 novel integrase-LEDGF/p75 allosteric inhibitors (INLAIs) based on a pyridine scaffold forming an intramolecular hydrogen bond. Scaffolds containing a pyridine moiety have been studied extensively and we have already reported that substituents extending from the C1 position contributed to the antiviral potency. In this study, we designed a new pyridine scaffold 2 with a substituent at the C1 position.

Discovery of novel integrase-LEDGF/p75 allosteric inhibitors based on a benzene scaffold.

We report herein the discovery of novel integrase-LEDGF/p75 allosteric inhibitors (INLAIs) based on a benzene scaffold 3. This scaffold can extend substituents from the C1 position unlike the common pyridine scaffolds 2. Structure-activity relationship studies showed that the sulfonamide linker at the C1 position was important for the antiviral activity.

Synthesis and SAR Study of Carbamoyl Pyridone Bicycle Derivatives as Potent Inhibitors of Influenza Cap-dependent Endonuclease.

The medicinal chemistry and structure-activity relationships (SAR) for a novel series of carbamoyl pyridone bicycle (CAB) compounds as influenza Cap-dependent endonuclease (CEN) inhibitors are disclosed. Substituent effects were evaluated at the C (N)-1, N-3, and C-7 positions of the CAB ring system using a docking study. Submicromolar EC values were achieved in the cellular assay with C-7-unsubstituted CAB which possessed a benzhydryl group on either the C-1 or the N-1 position.

Barrier to Resistance of Dolutegravir in Two-Drug Combinations.

A major concern when using two-drug anti-HIV regimens is the risk of viral resistance. However, no techniques to evaluate the barrier to resistance of two-drug combinations have been reported. We evaluated the emergence of drug-resistant mutants in a passage study with constant concentrations of two drugs simultaneously.

In vitro characterization of baloxavir acid, a first-in-class cap-dependent endonuclease inhibitor of the influenza virus polymerase PA subunit.

Cap-dependent endonuclease (CEN) resides in the PA subunit of the influenza virus and mediates the critical "cap-snatching" step of viral RNA transcription, which is considered to be a promising anti-influenza target. Here, we describe in vitro characterization of a novel CEN inhibitor, baloxavir acid (BXA), the active form of baloxavir marboxil (BXM). BXA inhibits viral RNA transcription via selective inhibition of CEN activity in enzymatic assays, and inhibits viral replication in infected cells without cytotoxicity in cytopathic effect assays.

Novel secondary mutations C56S and G149A confer resistance to HIV-1 integrase strand transfer inhibitors.

Cabotegravir (CAB, S/GSK1265744) is an investigational second-generation integrase strand transfer inhibitor (INSTI) with a chemical structure similar to dolutegravir. CAB is under development as a long-acting injectable formulation for treatment of HIV-1 infection and for pre-exposure prophylaxis. We conducted an in vitro passage study of raltegravir- or elvitegravir-resistant signature mutants in the presence of CAB to characterize the resistance profile of this drug.

Phosphorylation of the HIV-1 capsid by MELK triggers uncoating to promote viral cDNA synthesis.

Regulation of capsid disassembly is crucial for efficient HIV-1 cDNA synthesis after entry, yet host factors involved in this process remain largely unknown. Here, we employ genetic screening of human T-cells to identify maternal embryonic leucine zipper kinase (MELK) as a host factor required for optimal uncoating of the HIV-1 core to promote viral cDNA synthesis. Depletion of MELK inhibited HIV-1 cDNA synthesis with a concomitant delay of capsid disassembly.

Discovery of novel 5-hydroxy-4-pyridone-3-carboxy acids as potent inhibitors of influenza Cap-dependent endonuclease.

We report the discovery of a novel series of influenza Cap-dependent EndoNuclease (CEN) inhibitors based on the 4-pyridone-carboxylic acid (PYXA) scaffold, which were found from our chelate library. Our SAR research revealed the lipophilic domain to be the key to CEN inhibition. In particular, the position between the chelate and the lipophilic domain in the derivatives was essential for enhancing the potency.

Intravenous peramivir inhibits viral replication, and leads to bacterial clearance and prevention of mortality during murine bacterial co-infection caused by influenza A(H1N1)pdm09 virus and Streptococcus pneumoniae.

Introduction: Influenza virus infection increases susceptibility to bacterial infection and mortality in humans. Although the efficacy of approved intravenous peramivir, a neuraminidase (NA) inhibitor, against influenza virus infection has been reported, its efficacy against bacterial co-infection, which occurs during the period of viral shedding, was not fully investigated. To further understand the significance of treatment with peramivir, we assessed the efficacy of peramivir against a bacterial co-infection model in mice caused by clinically isolated influenza A(H1N1)pdm09 virus and Streptococcus pneumoniae.

Effects of raltegravir or elvitegravir resistance signature mutations on the barrier to dolutegravir resistance in vitro.

The recently approved HIV-1 integrase strand transfer inhibitor (INSTI) dolutegravir (DTG) (S/GSK1349572) has overall advantageous activity when tested in vitro against HIV-1 with raltegravir (RAL) and elvitegravir (EVG) resistance signature mutations. We conducted an in vitro resistance selection study using wild-type HIV-1 and mutants with the E92Q, Y143C, Y143R, Q148H, Q148K, Q148R, and N155H substitutions to assess the DTG in vitro barrier to resistance. No viral replication was observed at concentrations of ≥ 32 nM DTG, whereas viral replication was observed at 160 nM RAL or EVG in the mutants.

Antiviral characteristics of GSK1265744, an HIV integrase inhibitor dosed orally or by long-acting injection.

GSK1265744 is a new HIV integrase strand transfer inhibitor (INSTI) engineered to deliver efficient antiviral activity with a once-daily, low-milligram dose that does not require a pharmacokinetic booster. The in vitro antiviral profile and mechanism of action of GSK1265744 were established through integrase enzyme assays, resistance passage experiments, and cellular assays with site-directed molecular (SDM) HIV clones resistant to other classes of anti-HIV-1 agents and earlier INSTIs. GSK1265744 inhibited HIV replication with low or subnanomolar efficacy and with a selectivity index of at least 22,000 under the same culture conditions.

Dolutegravir interactions with HIV-1 integrase-DNA: structural rationale for drug resistance and dissociation kinetics.

Signature HIV-1 integrase mutations associated with clinical raltegravir resistance involve 1 of 3 primary genetic pathways, Y143C/R, Q148H/K/R and N155H, the latter 2 of which confer cross-resistance to elvitegravir. In accord with clinical findings, in vitro drug resistance profiling studies with wild-type and site-directed integrase mutant viruses have shown significant fold increases in raltegravir and elvitegravir resistance for the specified viral mutants relative to wild-type HIV-1. Dolutegravir, in contrast, has demonstrated clinical efficacy in subjects failing raltegravir therapy due to integrase mutations at Y143, Q148 or N155, which is consistent with its distinct in vitro resistance profile as dolutegravir's antiviral activity against these viral mutants is equivalent to its activity against wild-type HIV-1.

Carbamoyl pyridone HIV-1 integrase inhibitors 3. A diastereomeric approach to chiral nonracemic tricyclic ring systems and the discovery of dolutegravir (S/GSK1349572) and (S/GSK1265744).

We report herein the discovery of the human immunodeficiency virus type-1 (HIV-1) integrase inhibitors dolutegravir (S/GSK1349572) (3) and S/GSK1265744 (4). These drugs stem from a series of carbamoyl pyridone analogues designed using a two-metal chelation model of the integrase catalytic active site. Structure-activity studies evolved a tricyclic series of carbamoyl pyridines that demonstrated properties indicative of once-daily dosing and superior potency against resistant viral strains.

Carbamoyl pyridone HIV-1 integrase inhibitors. 2. Bi- and tricyclic derivatives result in superior antiviral and pharmacokinetic profiles.

This work is a continuation of our initial discovery of a potent monocyclic carbamoyl pyridone human immunodeficiency virus type-1 (HIV-1) integrase inhibitor that displayed favorable antiviral and pharmacokinetic properties. We report herein a series of bicyclic carbamoyl pyridone analogues to address conformational issues from our initial SAR studies. This modification of the core unit succeeded to deliver low nanomolar potency in standard antiviral assays.

Carbamoyl pyridone HIV-1 integrase inhibitors. 1. Molecular design and establishment of an advanced two-metal binding pharmacophore.

Our group has focused on expanding the scope of a two-metal binding pharmacophore concept to explore HIV-1 integrase inhibitors through medicinal chemistry efforts to design novel scaffolds which allow for improvement of pharmacokinetic (PK) and resistance profiles. A novel chelating scaffold was rationally designed to effectively coordinate two magnesium cofactors and to extend an aromatic group into an optimal hydrophobic pharmacophore space. The new chemotype, consisting of a carbamoyl pyridone core unit, shows high inhibitory potency in both enzymatic and antiviral assay formats with low nM IC₅₀ and encouraging potency shift effects in the presence of relevant serum proteins.

A strategy for neuraminidase inhibitors using mechanism-based labeling information.

A potent inhibitor for Vibrio cholerae neuraminidase (VCNA) was developed by using a novel two-step strategy, a target amino acid validation using mechanism-based labeling information, and a potent inhibitor search using a focused library. The labeling information suggested the hidden dynamics of a loop structure of VCNA, which can be a potential target of the novel inhibitor. A focused library composed of 187 compounds was prepared from a 9-azide derivative of 2,3-dehydro-N-acetylneuraminic acid (DANA) to interrupt the function of the loop of the labeled residues.

In Vitro antiretroviral properties of S/GSK1349572, a next-generation HIV integrase inhibitor.

S/GSK1349572 is a next-generation HIV integrase (IN) inhibitor designed to deliver potent antiviral activity with a low-milligram once-daily dose requiring no pharmacokinetic (PK) booster. In addition, S/GSK1349572 demonstrates activity against clinically relevant IN mutant viruses and has potential for a high genetic barrier to resistance. S/GSK1349572 is a two-metal-binding HIV integrase strand transfer inhibitor whose mechanism of action was established through in vitro integrase enzyme assays, resistance passage experiments, activity against viral strains resistant to other classes of anti-HIV agents, and mechanistic cellular assays.

Synthesis and antiviral activity of 7-benzyl-4-hydroxy-1,5-naphthyridin-2(1H)-one HIV integrase inhibitors.

The medicinal chemistry and structure-activity relationships for a novel series of 7-benzyl-4-hydroxy-1,5-naphthyridin-2(1H)-one HIV-integrase inhibitors are disclosed. Substituent effects were evaluated at the N-1, C-3, and 7-benzyl positions of the naphthyridinone ring system. Low nanomolar IC(50) values were achieved in an HIV-integrase strand transfer assay with both carboxylic ester and carboxamide groups at C-3.

Secondary mutations in viruses resistant to HIV-1 integrase inhibitors that restore viral infectivity and replication kinetics.

Passage of HIV-1 in the presence of integrase inhibitors (INIs) generates resistant viruses that have mutations in the integrase region. Integrase-resistant mutations Q148K and Q148R were identified as primary mutations with the passage of HIV-1 IIIB in the presence of INIs S-1360 or S/GSK-364735, respectively. Secondary amino acid substitutions E138K or G140S were observed when passage with INI was continued.

Selection of diverse and clinically relevant integrase inhibitor-resistant human immunodeficiency virus type 1 mutants.

Resistance passage studies were conducted with five INIs (integrase inhibitors) that have been tested in clinical trials to date: a new naphthyridinone-type INI S/GSK-364735, raltegravir, elvitegravir, L-870,810 and S-1360. In establishing the passage system and starting from concentrations several fold above the EC(50) value, resistance mutations against S-1360 and related diketoacid-type compounds could be isolated from infected MT-2 cell cultures from day 14 to 28. Q148R and F121Y were the two main pathways of resistance to S/GSK-364735.

The naphthyridinone GSK364735 is a novel, potent human immunodeficiency virus type 1 integrase inhibitor and antiretroviral.

The naphthyridinone GSK364735 potently inhibited recombinant human immunodeficiency virus type 1 (HIV-1) integrase in a strand transfer assay (mean 50% inhibitory concentration +/- standard deviation, 8 +/- 2 nM). As expected based on the structure of the drug, it bound competitively with another two-metal binding inhibitor (Kd [binding constant], 6 +/- 4 nM). In a number of different cellular assays, GSK364735 inhibited HIV replication with potency at nanomolar concentrations (e.

3-Hydroxy-1,5-dihydro-pyrrol-2-one derivatives as advanced inhibitors of HIV integrase.

The two-metal binding model we previously reported as an inhibition mechanism of HIV integrase (HIV IN) produced a new direction in modification of 2-hydroxy-3-heteroaryl acrylic acid inhibitors (HHAAs). Here we present a novel series of HIV IN inhibitors having a 3-hydroxy-1,5-dihydro-pyrrol-2-one moiety (HDPO) as an advanced analog of HHAAs. This cyclic modification of the chelating region of HHAA produces a favorable configuration to coordinate two-metal ions in HIV IN, which consequently gave improvements in not only enzymatic assay but also antiviral cell based assay in many cases.