Novel Non-nucleoside Reverse Transcriptase Inhibitor Research Articles

Escaping from Flatland: Multiparameter Optimization Leads to the Discovery of Novel Tetrahydropyrido[4,3-d]pyrimidine Derivatives as Human Immunodeficiency Virus-1 Non-nucleoside Reverse Transcriptase Inhibitors with Superior Antiviral Activities against Non-nucleoside Reverse Transcriptase Inhibitor-Resistant Variants and Favorable Drug-like Profiles.

In the current landscape of antiretroviral options, there remains an urgent need for novel non-nucleoside reverse transcriptase inhibitors (NNRTIs) with improved resistance profiles and safety properties. Herein, a series of novel tetrahydropyrido[4,3-d]pyrimidine derivatives were discovered utilizing the "escape from flatland" strategy. The most potent inhibitor 10c was endowed with broad-spectrum antiviral activity and improved resistance profiles against NNRTI-resistant variants compared to efavirenz and etravirine. Molecular simulations were investigated to furnish insights into the biological results. Drug-likeness assessment showed that 10c exhibited desirable physicochemical properties and in vitro metabolic stability. Notably, lower cytochrome P450 inhibition and human ether-à-go-go-related gene blockade liability were observed for 10c than those for etravirine and rilpivirine. Besides, 10c was characterized by excellent in vivo safety properties without acute/subacute toxicity and organ pathological damage. Overall, our multiparameter optimization campaign led to the identification of 10c with excellent antiviral activities and favorable drug-like profiles that could serve as an ideal drug candidate for further development.

Analytical Method Development and Validation for Determination of Doravirine by RP-HPLC

An easy, specific and precise RP-HPLC technique has been created and tested for the quantification of doravirine in pure and its tablet dosage forms. Doravirine is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI). It is utilized in the treatment of HIV-1 infection in combination with other antiviral medications therapies (ARTs). The separation was completed on the Agilent C18 column (150 x 4.6 mm) with 5µ particle size. 0.01N potassium dihydrogen phosphate and acetonitrile (ACN) (60:40 v/v), at a flow rate of 1ml/min, was used as an optimum mobile phase. The wavelength chosen was 210 nm. The retention time for doravirine was 2.379 min. Linearity of doravirine was found to be 25- 150μg/ml. Linearity equation attained was y= 11776x+ 2813 with correlation coefficient 0.999. The relative standard deviation for precision was found to be less than 2%. % Recovery was found as 100.13% for doravirine. The LOD and LOQ for doravirine were found as 0.06 µg/ml and 0.18 µg/ml. Keywords: Doravirine, Method Development, Validation, RP-HPLC

Low prevalence of doravirine-associated resistance mutations among polish human immunodeficiency-1 (HIV-1)-infected patients.

Doravirine (DOR) is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) that retains activity against common NNRTI resistance mutations. In this study, we aimed to investigate the prevalence of DOR resistance mutations compared with that of resistance mutations for other NNRTIs among HIV-1-infected treatment-experienced and -naïve patients from Poland. Resistance to DOR and other NNRTIs was assessed in two datasets: 1760 antiretroviral treatment-naïve HIV-1 patients and 200 treatment-experienced patients. All 1960 sequences were derived from the patients using bulk sequencing. For resistance analyses, Stanford HIV drug resistance database scores were used. Overall, DOR resistance was present in 32 patients (1.62%), of whom 13 (0.74%) were naïve and 19 (9.50%) were treatment-experienced. The most common DOR resistance mutations observed among the naïve patients were A98G and K101E (0.2% each), and those among cART-experienced patients were L100I (2.0%), K101E, V108I, H221Y, and P225H (1.5% each). Furthermore, among the naïve patients, less common resistance to DOR (0.7%) compared with that to nevirapine (NVP) (2.1%; p = 0.0013) and rilpivirine (5.40%; p < 0.0001) was observed. For sequences obtained from treatment-experienced patients, the frequency of resistance to DOR (9.5%) was lower than that for efavirenz (25.5%; p < 0.0001) and NVP (26.0%; p < 0.0001). The frequency of transmitted drug resistance to DOR is low, allowing for effective treatment of antiretroviral treatment-naïve patients and rapid treatment initiation. In cART-experienced patients, this agent remains an attractive NNRTI option with a higher genetic barrier to resistance.

Design and in silico screening of analogs of rilpivirine as novel non-nucleoside reverse transcriptase inhibitors (NNRTIs) for antiretroviral therapy

Part of the retroviral genus, the human immunodeficiency virus (HIV) relies on the host’s cellular machinery for replication. The viral genetic material is composed of ribonucleic acid (RNA) which, upon delivery into the host’s cells, is reverse transcribed into deoxyribonucleic acid (DNA) by the viral enzyme reverse transcriptase (RT). This is then used for the production of new viral components, thus allowing for further replication and spread of HIV. Because this virus selectively targets CD4+ T cells, the infection inevitably leads to weakening of the host’s immune system, which can then lead to acquired immunodeficiency syndrome (AIDS). One treatment for HIV is non-nucleoside reverse transcriptase inhibitors (NNRTIs), which are allosteric inhibitors of RT that disable the enzyme’s activity and thus viral replication. Previous NNRTIs approved for clinical use by the United States Food and Drug Association (FDA) include etravirine, doravirine, and rilpivirine. However, resistance to these drugs through mutations in RT necessitates the continued development of NNRTIs. Here, the structure of rilpivirine, a relatively recently FDA approved NNRTI, was used to design a library of analogs that were then evaluated in silico via high-throughput virtual screening (HTVS). From this, several structures were identified as potential next-generation NNRTIs with comparable predicted binding affinities to the allosteric binding pocket in RT as rilpivirine.

Review of Doravirine Resistance Patterns Identified in Participants During Clinical Development.

Background:Doravirine (DOR) is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) approved for the treatment of HIV-1 infection in patients with no known DOR resistance-associated mutations. DOR was rationally designed to address limitations associated with other approved NNRTIs, particularly resistance from common NNRTI resistance-associated mutants containing K103N, Y181C, or G190A reverse transcriptase substitutions.Setting:Data to date from both in vitro studies and clinical trials have been compiled to summarize the resistance profile of DOR.Methods:We analyzed data from in vitro studies and phase 2 and 3 trials to assess the emergence of resistance-associated mutations and their impact on efficacy among participants treated with DOR.Results:DOR exhibited a distinct resistance profile compared with efavirenz and rilpivirine in vitro and in vivo; mutant viruses that were resistant to DOR showed limited cross-resistance to efavirenz and rilpivirine. In clinical trials, the development of DOR resistance-associated substitutions in reverse transcriptase was uncommon.Conclusion:Overall, minimal cross-resistance across NNRTIs was observed for DOR and limited development of DOR-related resistance. These data should assist clinicians in further understanding the resistance profile of DOR, so appropriate treatment decisions can be made for their patients.

Privileged scaffold inspired design of novel oxime-biphenyl-DAPYs in treatment of HIV-1.

Oxime is a key pharmacophore in drug development. The biphenyl diarylpyrimidines (DAPYs) have been developed by our group as novel non-nucleoside reverse transcriptase inhibitors (NNRTIs). In this study, fourteen oxime-biphenyl-DAPYs were designed and synthesized through a privileged scaffold inspired design strategy. They exhibited promising activity toward wild type HIV-1 and single mutant strains. Compound 7d was found to be the most potent one against both wild type (EC50=12.1nM) and E138K mutant strains (EC50=0.0270µM). It also had a much lower cytotoxicity (CC50>292µM) and higher selective index (SI>24105) than those of the FDA-approved drugs efavirenz and etravirine. Molecular docking and dynamics simulation predicted and disclosed the binding mode of compound 7d with the RT, providing the explanation on the antiviral activity. These results were helpful for subsequent structural optimizations in anti-HIV-1 drug discovery.

Clinical Pharmacodynamics, Pharmacokinetics, and Drug Interaction Profile of Doravirine.

Doravirine is a novel non-nucleoside reverse transcriptase inhibitor(NNRTI) that has demonstrated good efficacy, tolerability, and safety for the treatment of patients with human immunodeficiency virus (HIV)-1 infection in phase III clinical trials. Doravirine achieved non-inferiority when compared with efavirenz- and darunavir/ritonavir-based regimens. Fewer adverse effects, including neuropsychiatric effects were observed with doravirine compared with efavirenz. Key pharmacodynamic and pharmacokinetic characteristics as well as drug-drug interactions and the resistance profile were assessed in this clinical review. Doravirine is a pyridinone NNRTI with potent antiviral activity against wild-type HIV-1 virus and common NNRTI variants. Studies in healthy volunteers and HIV-infected individuals have shown that doravirine has a favorable pharmacokinetic profile for once-daily dosing, with an elimination half-life of around 15h, median time to maximum plasma concentrations of 1-4h, and time to steady-state concentration of 7days. The pharmacokinetics of doravirine arenot greatly influenced by sex, age, race, or hepatic impairment. Although no dose adjustment is required for doravirine in renal impairment when given as a single tablet, the fixed-dose combination tablet of doravirine/lamivudine/tenofovir disoproxil fumarate is not recommended in patients with a creatinine clearance of < 50mL/min. Doravirine has a low potential for drug-drug interactions and does not impact on the pharmacokinetics of other drugs. However, it is metabolized via cytochrome P450 (CYP) 3A enzymes and is thus susceptible to interactions with CYP3A inhibitors and inducers. Strong CYP3A inhibitors can significantly increase doravirine exposure; however, this is not considered to be clinically relevant. Conversely, strong CYP3A inducers, such as rifampin, are contraindicated with doravirine owing to a significant reduction in exposure with potential for impaired virological efficacy. Moderate CYP3A inducers, such as rifabutin, may be co-administered if the doravirine dose is increased to 100mg twice daily. Doravirine has a unique resistance profile and has demonstrated in vitro activity against some of the most common, clinically relevant NNRTI-resistant mutations. Prevalence of baseline NNRTI resistance to doravirine appears to be low in treatment-naïve cohorts. Further data on the efficacy of doravirine in patients with previous treatment experience and/or transmitted NNRTI resistance are required to further inform its place in the current armamentarium of drugs for the treatment of HIV infection.

Two Coselected Distal Mutations in HIV-1 Reverse Transcriptase (RT) Alter Susceptibility to Nonnucleoside RT Inhibitors and Nucleoside Analogs.

Two mutations, G112D and M230I, were selected in the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) by a novel nonnucleoside reverse transcriptase inhibitor (NNRTI). G112D is located near the HIV-1 polymerase active site; M230I is located near the hydrophobic region where NNRTIs bind. Thus, M230I could directly interfere with NNRTI binding but G112D could not. Biochemical and virological assays were performed to analyze the effects of these mutations individually and in combination. M230I alone caused a reduction in susceptibility to NNRTIs, while G112D alone did not. The G112D/M230I double mutant was less susceptible to NNRTIs than was M230I alone. In contrast, both mutations affected the ability of RT to incorporate nucleoside analogs. We suggest that the mutations interact with each other via the bound nucleic acid substrate; the nucleic acid forms part of the polymerase active site, which is near G112D. The positioning of the nucleic acid is influenced by its interactions with the "primer grip" region and could be influenced by the M230I mutation.IMPORTANCE Although antiretroviral therapy (ART) is highly successful, drug-resistant variants can arise that blunt the efficacy of ART. New inhibitors that are broadly effective against known drug-resistant variants are needed, although such compounds might select for novel resistance mutations that affect the sensitivity of the virus to other compounds. Compound 13 selects for resistance mutations that differ from traditional NNRTI resistance mutations. These mutations cause increased sensitivity to NRTIs, such as AZT.

546. No Difference in MK-8591 and Doravirine Pharmacokinetics After Co-Administration

BackgroundMK-8591 is a novel, highly potent, nucleoside reverse transcriptase translocation inhibitor (NRTTI) that is in development for the treatment of HIV-1 infection. MK-8591 is not expected to be a perpetrator or victim of drug–drug interactions (DDI), as it does not interact with renal or hepatic transporters, or with cytochrome P450 (CYP) enzymes in vitro. Doravirine (DOR), a novel non-nucleoside reverse transcriptase inhibitor (NNRTI), does not interact significantly with hepatic transporters or CYP enzymes but is metabolized by CYP3A4 in vitro. As MK-8591 is neither an inducer nor an inhibitor of CYP3A4, an interaction between MK-8591 and DOR was not expected. Currently, MK-8591 is being evaluated in a Phase 2 trial in combination with DOR.MethodsThe two-way interaction between MK-8591 and DOR was investigated in a double-blind, placebo-controlled, randomized, fixed-sequence, two-way drug–drug interaction study in 14 healthy adult subjects. Subjects received 5 days of 100 mg DOR or placebo QD, followed by 19 days of 2.25 mg MK-8591 or placebo QD, with 100 mg DOR or placebo co-administered QD for the last 5 days. Ten subjects received active drug and four received placebo throughout the trial.ResultsMultiple daily doses of MK-8591 and DOR alone and in combination were generally well tolerated. As noted in the table, the DOR area under the curve from time zero to 24 hours (AUC0-24), concentration at 24 hours (C24), and maximum concentration (Cmax) were similar with and without MK-8591, and the MK-8591 AUC0-24 and Cmax were similar with and without DOR.Table: Geometric Mean Ratio (GMR) with 90% Confidence Interval, Relative to Single Agent Administration (N = 10)DORMK-8591AUC0-241.13 [1.01, 1.28]1.06 [1.01, 1.12]C24†1.12 [0.95, 1.32]Cmax1.11 [0.99, 1.25]1.08 [0.91, 1.27] †C24 for parent MK-8591 is not related to efficacy and therefore not included.ConclusionNo clinically significant differences in PK were observed when MK-8591 and DOR were co-administered, which supports the Phase 2 co-dosing of MK-8591 and DOR. Consistent across trials, MK-8591 does not appear to interact with CYP3A4-mediated metabolism.Disclosures R. Matthews, Merck: Employee and Shareholder, Salary. D. Rudd, Merck: Employee and Shareholder, Salary. K. Fillgrove, Merck & Co., Inc.: Employee, Salary. S. Fox-Bosetti, Merck: Employee and Shareholder, Salary. V. Levine, Merck: Employee and Shareholder, Salary. S. Zhang, Merck & Co, Inc.: Employee, Salary. C. Tomek, Merck: Research Contractor, Research support and Salary. A. Stoch, Merck & Co, Inc.: Employee and Shareholder, Salary. M. Iwamoto, Merck & Co, Inc.:. Employee and Shareholder, Salary.

LB1. Doravirine/Lamivudine/Tenofovir DF Continues to Be NonInferior to Efavirenz/Emtricitabine/Tenofovir DF in Treatment-Naïve Adults With HIV-1 Infection: Week 96 Results of the DRIVE-AHEAD Trial

BackgroundDoravirine (DOR) is a novel non-nucleoside reverse-transcriptase inhibitor (NNRTI). In the phase 3 DRIVE-AHEAD trial in HIV-1-infected treatment-naïve adults, DOR demonstrated noninferior efficacy to efavirenz (EFV) and favorable profiles for neuropsychiatric tolerability and lipids at 48 weeks. We present data through week 96.MethodsDRIVE- AHEAD (Clinical Trials Registration: NCT02403674) is a phase 3, multicenter, double-blind, noninferiority trial that compared DOR with EFV. Eligible participants were HIV-1-infected treatment-naïve adults with pre-treatment HIV-1 RNA ≥1,000 copies/mL. Participants were randomized (1:1) to a fixed-dose regimen of DOR 100 mg, lamivudine 300 mg and tenofovir disoproxil fumarate 300 mg (DOR/3TC/TDF) QD or EFV 600 mg, emtricitabine 200 mg and TDF 300 mg (EFV/FTC/TDF) QD for up to 96 weeks. Randomization was stratified by screening HIV-1 RNA (≤/>100,000 copies/mL) and hepatitis B/C co-infection (yes/no). The efficacy endpoint of interest at week 96 was HIV-1 RNA <50 copies/mL with predefined noninferiority margin of 10%. Safety endpoints of interest included occurrence of pre-specified neuropsychiatric adverse events and mean change from baseline in fasting lipid levels at week 96.ResultsOf 734 participants randomized, 728 received study drug and were included in analyses (mean age 33 years, 85% male, 48% white, 19% black, 34% Hispanic). At week 96, HIV-1 RNA <50 copies/mL was achieved by 77.5% of DOR/3TC/TDF recipients vs. 73.6% of EFV/FTC/TDF recipients (difference 3.8%, 95%CI [−2.4, 10.0]). No additional phenotypic resistance to DOR was observed between weeks 48 and 96, while two additional participants in the EFV/FTC/TDF group developed resistance to EFV. Dizziness, sleep disorders/disturbances, altered sensorium, and rash were less frequent in DOR/3TC/TDF recipients than in EFV/FTC/TDF recipients. Fasting LDL-C and non-HDL-C increased in the EFV/FTC/TDF group but not in the DOR/3TC/TDF group, while change in total cholesterol/HDL-C ratio was similar.ConclusionWeek 96 results support non-inferiority of DOR/3TC/TFD to EFV/FTC/TDF established at Week 48 with no additional DOR resistance between week 48 and 96. DOR/3TC/TDF was safe and well-tolerated with fewer neuropsychiatric and rash events and favorable lipid profile compared with EFV/FTC/TDF.Disclosures C. Orkin, AbbVie, Abbott, Boehringer Ingelheim, BMS, Gilead, GSK, Janssen, ViiV: Grant Investigator and Research Contractor, Research grant and Research support. K. Squires, Merck & Co., Inc.: Ad Board, Ad Board. Gilead Sciences: Grant, Ad Board. VIIV: Ad Board, Ad Board. Bristol Myers Squibb: Ad Board, Ad Board. Janssen: Ad Board, Ad Board. J. M. Molina, Gilead: Scientific Advisor, Consulting fee. Merck: Scientific Advisor, Consulting fee. ViiV: Scientific Advisor, Consulting fee. Teva: Scientific Advisor, Consulting fee. P. Sax, Gilead: Consultant and Grant Investigator, Consulting fee, Grant recipient and Research grant. ViiV Healthcare: Consultant and Grant Investigator, Consulting fee, Grant recipient and Research grant. Merck: Consultant and Grant Investigator, Consulting fee, Grant recipient and Research grant. Janssen: Consultant, Consulting fee. BMS: Grant Investigator, Grant recipient and Research grant. W. Wong, Merck & Co., Inc.: Research Contractor, Research grant. G. Lin, Merck Sharp & Dohme, a subsidiary of Merck & Co., Inc.: Employee and Shareholder, May hold stock/stock options in the company and Salary. S. Kumar, Merck & Co., Inc.: Employee and Shareholder, Salary. G. Hanna, Merck & Co., Inc.: Employee and Shareholder, Salary. C. Hwang, Merck & Co., Inc.: Employee and Shareholder, Salary. E. Martin, Merck & Co., Inc.: Employee and Shareholder, Salary. H. Teppler, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA: Employee, May hold stock/stock options in the company and Salary.

Structural basis for potent and broad inhibition of HIV-1 RT by thiophene[3,2-d]pyrimidine non-nucleoside inhibitors.

Rapid generation of drug-resistant mutations in HIV-1 reverse transcriptase (RT), a prime target for anti-HIV therapy, poses a major impediment to effective anti-HIV treatment. Our previous efforts have led to the development of two novel non-nucleoside reverse transcriptase inhibitors (NNRTIs) with piperidine-substituted thiophene[3,2-d]pyrimidine scaffolds, compounds K-5a2 and 25a, which demonstrate highly potent anti-HIV-1 activities and improved resistance profiles compared with etravirine and rilpivirine, respectively. Here, we have determined the crystal structures of HIV-1 wild-type (WT) RT and seven RT variants bearing prevalent drug-resistant mutations in complex with K-5a2 or 25a at ~2 Å resolution. These high-resolution structures illustrate the molecular details of the extensive hydrophobic interactions and the network of main chain hydrogen bonds formed between the NNRTIs and the RT inhibitor-binding pocket, and provide valuable insights into the favorable structural features that can be employed for designing NNRTIs that are broadly active against drug-resistant HIV-1 variants.

Doravirine versus ritonavir-boosted darunavir in antiretroviral-naive adults with HIV-1 (DRIVE-FORWARD): 48-week results of a randomised, double-blind, phase 3, non-inferiority trial

Doravirine is a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) with a pharmacokinetic profile supporting once-daily dosing, and potent in-vitro activity against the most common NNRTI-resistant HIV-1 variants. We compared doravirine with ritonavir-boosted darunavir, when both were given with two nucleoside reverse transcriptase inhibitors (NRTIs), in adults with previously untreated HIV-1 infection. In this randomised, controlled, double-blind, multicentre, non-inferiority trial, adults with HIV-1 infection were screened and enrolled at 125 clinical centres in 15 countries. Eligible participants (aged ≥18 years) were naive to antiretroviral therapy with plasma HIV-1 RNA of at least 1000 copies per mL at screening. Participants who had previously been treated for a viral infection other than HIV-1, those taking immunosuppressive drugs, and individuals with active acute hepatitis were excluded. Participants were randomly assigned (1:1) via an interactive voice and web response system to receive oral doravirine 100 mg or darunavir 800 mg plus ritonavir 100 mg once daily, with two investigator-selected NRTIs (tenofovir and emtricitabine or abacavir and lamivudine) for up to 96 weeks. Randomisation was stratified by HIV-1 RNA measurements at screening (≤100 000 vs >100 000 copies per mL) and the NRTI pair. Study participants, funding institution staff, investigators, and study site personnel were masked to treatment group assignment. The primary efficacy endpoint was the proportion of participants achieving HIV-1 RNA of less than 50 copies per mL at week 48 defined by the US Food and Drug Administration snapshot algorithm, with non-inferiority established if the lower bound of the two-sided 95% CI for the treatment difference (doravirine minus darunavir) was greater than -10 percentage points. All participants who received at least one dose of study drug were included in the primary efficacy and safety analyses. This trial is active, but not recruiting, and is registered with ClinicalTrials.gov, number NCT02275780. Between Dec 1, 2014, and Oct 20, 2015, 1027 participants were screened for eligibility, of whom 769 participants were randomly assigned to treatment (385 with doravirine and 384 with ritonavir-boosted darunavir). 56 participants discontinued treatment in the doravirine group compared with 71 in the darunavir group, mostly due to loss to follow-up. 383 participants who received doravirine and 383 who received darunavir were included in the primary efficacy analyses. At week 48, 321 (84%) participants in the doravirine group and 306 (80%) in the darunavir group achieved plasma HIV-1 RNA of less than 50 copies per mL (difference 3·9%, 95% CI -1·6 to 9·4), indicating non-inferiority of the doravirine regimen. The most common study drug-related adverse events were diarrhoea (21 [5%] of 383 participants in the doravirine group and 49 [13%] of 383 participants in the darunavir group), nausea (25 [7%] vs 29 [8%]), and headache (23 [6%] vs ten [3%]). 18 participants (six [2%] of 383 participants in the doravirine group vs 12 [3%] of 383 participants in the darunavir group) discontinued treatment due to adverse events, which were considered drug-related in four (1%) participants in the doravirine group and 8 (2%) participants in the darunavir group. Serious adverse events occurred in 19 (5%) of 383 participants in the doravirine group and 23 (6%) of 383 in the darunavir roup, and were considered study-drug related in one (<1%) participant of each group. In treatment-naive adults with HIV-1 infection, doravirine combined with two NRTIs might offer a valuable treatment option for adults with previously untreated HIV-1 infection. Merck & Co.

Identification of cytochrome P450s involved in the metabolism of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1) using human recombinant enzymes and rat liver microsomes in vitro

1. The aim of this study was to identify the hepatic metabolic enzymes, which involved in the biotransformation of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) in rat and human in vitro.2. The parent drug of W-1 was incubated with rat liver microsomes (RLMs) or recombinant CYPs (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5, respectively) in the presence or absence of nicotinamide adeninedinucleotide phosphate (NADPH)-regenerating system. The metabolites of W-1 were analyzed with liquid chromatography-ion trap-time of flight-mass spectrometry (LC-IT-TOF-MS).3. The parent drug of W-1 was metabolized in a NADPH-dependent manner in RLMs. The kinetic parameters of prototype W-1 including Km, Vmax, and CLint were 2.3 μM, 3.3 nmol/min/mg protein, and 1.4 mL/min/mg protein, respectively. Two metabolites M1 and M2 were observed in shorter retention times (2.988 and 3.188 min) with a higher molecular ion at m/z 463.0160 (both M1 and M2) than that of the W-1 parent drug (6.158 min with m/z 447.0218). The CYP selective inhibition and recombinant enzymes also showed that two hydroxyl metabolites M1 and M2 are mainly mediated by CYP2C19 and CYP3A4.4. The identification of CYPs involved in W-1 biotransformation is important to understand and minimize, if possible, the potential of drug–drug interactions.

Synthesis and biological evaluation of pyridazine derivatives as novel HIV-1 NNRTIs

In continuation of our efforts toward identification and optimization of novel non-nucleoside reverse transcriptase inhibitors (NNRTIs), we have employed a structure-based bioisosterism strategy, with which a new series of diarylpyridazine (DAPD) derivatives were synthesized and evaluated for their anti-HIV-1 (human immunodeficiency virus type 1) activity. Most of the title compounds displayed excellent anti-HIV-1 activity at submicromolar concentrations ranging from 34nM to 5.08μM. The most promising compound 8g inhibited HIV-1 IIIB in MT-4 cells at a low EC50 value (0.034μM), which was lower than the reference drug nevirapine and delavirdine. The structure activity relationships (SARs) were discussed and rationalized by docking simulations.

Divide‐and‐conquer‐based quantum chemical study for interaction between HIV‐1 reverse transcriptase and MK‐4965 inhibitor

AbstractMK‐4965, 3‐{5‐[(6‐Amino‐1H‐pyrazolo[3,4‐b]pyridine‐3‐yl)methoxy]‐2‐chlorophenoxy}‐5‐chloro‐benzonitrile, is a novel non‐nucleoside reverse transcriptase inhibitor (NNRTI) revealing high levels of potency against wild‐type (WT) the human immunodeficiency virus type‐1 (HIV‐1) and some important mutants. The divide‐and‐conquer (DC) based Hartree–Fock (HF) and second‐order Møller–Plesset perturbation theory (MP2) calculations were performed for the binding modes of MK‐4965 in the reverse transcriptase (RT) of the WT HIV‐1 and a mutant Y181C, 181 tyrosine mutated by cysteine. The binding pockets of MK‐4965 consisting of 19 residues are selected for the study. Numerical assessments confirmed the efficiency and accuracy of the DC‐MP2 method in comparison with the conventional MP2 one. Subsystem interaction energies obtained by the DC‐MP2 calculations clarified the key parts of the binding between MK‐4965 and HIV‐1: hydrogen bonding with 102 lysine, which is apart from mutated 181 residue. The present information can give a helpful guide for the future inhibitor design. © 2012 Wiley Periodicals, Inc.

Antiviral Activity andIn VitroMutation Development Pathways of MK-6186, a Novel Nonnucleoside Reverse Transcriptase Inhibitor

MK-6186 is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) which displays subnanomolar potency against wild-type (WT) virus and the two most prevalent NNRTI-resistant RT mutants (K103N and Y181C) in biochemical assays. In addition, it showed excellent antiviral potency against K103N and Y181C mutant viruses, with fold changes (FCs) of less than 2 and 5, respectively. When a panel of 12 common NNRTI-associated mutant viruses was tested with MK-6186, only 2 relatively rare mutants (Y188L and V106I/Y188L) were highly resistant, with FCs of >100, and the remaining viruses showed FCs of <10. Furthermore, a panel of 96 clinical virus isolates with NNRTI resistance mutations was evaluated for susceptibility to NNRTIs. The majority (70%) of viruses tested displayed resistance to efavirenz (EFV), with FCs of >10, whereas only 29% of the mutant viruses displayed greater than 10-fold resistance to MK-6186. To determine whether MK-6186 selects for novel resistance mutations, in vitro resistance selections were conducted with one isolate each from subtypes A, B, and C under low-multiplicity-of-infection (MOI) conditions. The results showed a unique mutation development pattern in which L234I was the first mutation to emerge in the majority of the experiments. In resistance selection under high-MOI conditions with subtype B virus, V106A was the dominant mutation detected in the breakthrough viruses. More importantly, mutant viruses selected by MK-6186 showed FCs of <10 against EFV or etravirine (ETR), and the mutant viruses containing mutations selected by EFV or ETR were sensitive to MK-6186 (FCs of <10).

Interaction Potential of Etravirine with Drug Transporters Assessed In Vitro

Etravirine is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) for the treatment of HIV-1 infections. ABC transporters potentially mediate clinically relevant drug-drug interactions. We assessed substrate characteristics and the inhibitory and inductive potential of etravirine on ABC transporters. Etravirine did not inhibit P-gp/ABCB1 and was not transported by the tested ABC transporters but was a potent inhibitor of BCRP/ABCG2. Etravirine induced several ABC transporters, especially BCRP/ABCG2. These data demonstrate that etravirine has the potential for drug-drug interactions by modulation of expression and function of several ABC transporters.

Differential impact of the HIV-1 non-nucleoside reverse transcriptase inhibitor mutations K103N and M230L on viral replication and enzyme function

We wished to study the resistance profile of etravirine, a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) active against common human immunodeficiency virus type-1 (HIV-1) drug-resistant strains. We compared the effects of K103N, the most prevalent NNRTI resistance mutation, and M230L on enzyme function, virus replication and extent of biochemical inhibition by etravirine, efavirenz and nevirapine. Growth kinetics analyses in cord blood mononuclear cells (CBMCs) demonstrated that K103N-containing virus replicated as well as wild-type (WT) virus and that the M230L-containing virus was severely impaired in replication ability in the absence of NNRTIs. K103N-containing viruses replicated well in the presence of efavirenz and nevirapine, while virus containing M230L displayed substantial replication in the presence of all NNRTIs tested. RNA-dependent DNA polymerase assays using a heterogeneous HIV-1 RNA template and purified recombinant WT or mutated reverse transcriptase enzymes revealed that the fold change (FC) for etravirine was 0.7 for K103N and 8 for M230L. K103N and M230L conferred high-level resistance to both efavirenz (FC=39 and 15.3, respectively) and nevirapine (FC=43.5 and 33), confirming that M230L confers cross-resistance to both drugs while K103N-containing viruses remain susceptible to etravirine. In enzymatic assays, the K103N mutation was associated with moderate reductions in the efficiency of 3' DNA end-directed RNA template cleavage, while comparable efficiency to WT enzyme was observed with regard to minus-strand strong stop DNA synthesis and polymerase processivity. These properties help to explain differences in the evolution and prevalence of these two NNRTI mutations.

Phase 2a Randomized Controlled Trial of Short-Term Activity, Safety, and Pharmacokinetics of a Novel Nonnucleoside Reverse Transcriptase Inhibitor, RDEA806, in HIV-1-Positive, Antiretroviral-Naïve Subjects

RDEA806 is a novel nonnucleoside reverse transcriptase inhibitor (NNRTI) with potent in vitro activity against wild-type and NNRTI-resistant HIV-1. A phase 2a randomized, double-blind, placebo-controlled, dose-escalating study evaluated the short-term antiviral activity, safety, and pharmacokinetics (PKs) of RDEA806 monotherapy in antiretroviral-naïve, HIV-1-infected subjects. The subjects were randomized to four cohorts comprising four dosage regimens and two formulations of RDEA806 or placebo in a 3:1 ratio within each cohort. The investigators were blinded to the results for each cohort. The subjects received RDEA806 or placebo for 7 days. The primary end point was the change in the HIV RNA load from the baseline to day 9 for each of the four RDEA806 dose regimens compared to that achieved with placebo. The RDEA806 PKs and the immune response to RDEA806 were evaluated along with the safety and tolerability of each dose. Of a total of 48 enrolled subjects, 36 subjects (9 in each cohort) were randomized to RDEA806 study drug, and 12 (3 in each cohort) took placebo. A statistically significant decrease in the viral load from the baseline to day 9 was observed for all RDEA806 treatment groups (P<0.001). On day 9, the mean changes in the HIV RNA load from that at the baseline were -1.95 log10 copies/ml (400 mg twice a day), -1.39 log10 copies/ml (600 mg once a day [q.d.]), -1.62 log10 copies/ml (800 mg q.d.), and -1.70 log1) copies/ml (1,000 mg q.d.). The pharmacokinetics were linear and dose proportional. Treatment with RDEA806 was well tolerated, and there were no discontinuations due to adverse events. In conclusion, all doses of RDEA806 were safe and well tolerated and exhibited robust antiretroviral activity in this short-term monotherapy study with antiretroviral-naïve HIV-infected subjects. RDEA806 is a potent and promising novel NNRTI.

Convenient preparation of 4-aryl-2-(heteroarylamino)pyrimidines and 4-anilino-2-(heteroarylamino)pyrimidines

Abstract 4-Aryl-2-anilinopyrimidines and 2,4-dianilinopyrimidines are privileged structures found in many drug-like molecules and biologically active compounds. A method for the quick assembly of novel 4-aryl- and 4-anilino-2-(heteroarylamino)pyrimidines via Buchwald–Hartwig N-arylations at elevated temperatures under sealed tube conditions is reported. This method’s convenience and practicality is demonstrated through the preparation of several novel non-nucleoside reverse transcriptase inhibitor (NNRTI) analogues.