ABSTRACT
Lenacapavir (LEN), a long-acting injectable, is the first approved human immunodeficiency virus type 1 capsid inhibitor and one of a few FDA-approved drugs that exhibit atropisomerism. LEN exists as a mixture of two class 2 atropisomers that interconvert at a fast rate (t1/2 <2 hours) with a ratio that is stable over time and unaffected by enzymes or binding to proteins in plasma. LEN exhibits low systemic clearance (CL) in nonclinical species and humans; however, in all species the observed CL was higher than the in vitro predicted CL. The volume of distribution was moderate in nonclinical species and consistent with the tissue distribution observed by whole body autoradiography in rats. LEN does not distribute to brain, consistent with being a P-glycoprotein (P-gp) substrate. Mechanistic drug disposition studies with [14C]LEN in IV-dosed BDC rats and dogs showed a substantial amount of unchanged LEN (31 - 60% of dose) excreted in feces, indicating that intestinal excretion (IE) was a major clearance pathway for LEN in both species. Coadministration of oral elacridar, a P-gp inhibitor, in rats decreased CL and IE of LEN. Renal excretion was <1% of dose in both species. In plasma, almost all radioactivity was unchanged LEN. Low levels of metabolites in excreta included LEN-conjugates with glutathione, pentose, and glucuronic acid, which were consistent with metabolites formed in vitro in Hµrel® hepatocyte cocultures and those observed in human. Our studies highlight the importance of IE for efflux substrates that are highly metabolically stable compounds with slow elimination rates. Significance Statement LEN is a long-acting injectable that exists as conformationally stable atropisomers. Due to an atropisomeric interconversion rate that significantly exceeds the in vivo elimination rate, the atropisomer ratio of LEN remains constant in circulation. The disposition of LEN highlights that intestinal excretion has a substantial part in the elimination of compounds that are metabolically highly stable and efflux transporter substrates.
ABSTRACT
Chronic hepatitis B (CHB) virus infection afflicts hundreds of millions of people and causes nearly one million deaths annually. The high levels of circulating viral surface antigen (HBsAg) that characterize CHB may lead to T-cell exhaustion, resulting in an impaired antiviral immune response in the host. Agents that suppress HBsAg could help invigorate immunity toward infected hepatocytes and facilitate a functional cure. A series of dihydropyridoisoquinolizinone (DHQ) inhibitors of human poly(A) polymerases PAPD5/7 were reported to suppress HBsAg in vitro. An example from this class, RG7834, briefly entered the clinic. We set out to identify a potent, orally bioavailable, and safe PAPD5/7 inhibitor as a potential component of a functional cure regimen. Our efforts led to the identification of a dihydropyridophthalazinone (DPP) core with improved pharmacokinetic properties. A conformational restriction strategy and optimization of core substitution led to GS-8873, which was projected to provide deep HBsAg suppression with once-daily dosing.
ABSTRACT
BACKGROUND: The ExteNET trial demonstrated improved invasive disease-free survival (iDFS) with neratinib, an irreversible pan-HER tyrosine kinase inhibitor, versus placebo in patients with human epidermal growth factor receptor 2-positive (HER2+)/hormone receptor-positive (HR+) early-stage breast cancer (eBC). PATIENTS AND METHODS: ExteNET was a multicenter, randomized, double-blind, phase III trial of 2840 patients with HER2+ eBC after neoadjuvant/adjuvant trastuzumab-based therapy. Patients were stratified by HR status and randomly assigned 1-year oral neratinib 240 mg/day or placebo. The primary endpoint was iDFS. Descriptive analyses were performed in patients with HR+ eBC who initiated treatment ≤ 1 year (HR+/≤ 1-year) and > 1 year (HR+/> 1-year) post-trastuzumab. RESULTS: HR+/≤ 1-year and HR+/> 1-year populations comprised 1334 (neratinib, n = 670; placebo, n = 664) and 297 (neratinib, n = 146; placebo, n = 151) patients, respectively. Absolute iDFS benefits at 5 years were 5.1% in HR+/≤ 1-year (hazard ratio, 0.58; 95% confidence interval [CI], 0.41-0.82) and 1.3% in HR+/>1-year (hazard ratio, 0.74; 95% CI, 0.29-1.84). In HR+/≤ 1-year, neratinib was associated with a numerical improvement in overall survival (OS) at 8 years (absolute benefit, 2.1%; hazard ratio, 0.79; 95% CI, 0.55-1.13). Of 354 patients in the HR+/≤ 1-year group who received neoadjuvant therapy, 295 had residual disease, and results showed absolute benefits of 7.4% at 5-year iDFS (hazard ratio, 0.60; 95% CI, 0.33-1.07) and 9.1% at 8-year OS (hazard ratio, 0.47; 95% CI, 0.23-0.92). There were fewer central nervous system events with neratinib. Adverse events were similar to those previously reported. CONCLUSION: Neratinib significantly improved iDFS in the HER2+/HR+/≤ 1-year population, and a similar trend was observed in patients with residual disease following neoadjuvant treatment. Numerical improvements in central nervous system events and OS were consistent with iDFS benefits and suggest long-term benefit for neratinib in this population.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Breast Neoplasms/drug therapy , Quinolines/therapeutic use , Receptor, ErbB-2/metabolism , Adult , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Disease-Free Survival , Dose-Response Relationship, Drug , Double-Blind Method , Female , Follow-Up Studies , Humans , Middle Aged , Neoplasm Staging , Treatment OutcomeABSTRACT
Oral antiretroviral agents provide life-saving treatments for millions of people living with HIV, and can prevent new infections via pre-exposure prophylaxis1-5. However, some people living with HIV who are heavily treatment-experienced have limited or no treatment options, owing to multidrug resistance6. In addition, suboptimal adherence to oral daily regimens can negatively affect the outcome of treatment-which contributes to virologic failure, resistance generation and viral transmission-as well as of pre-exposure prophylaxis, leading to new infections1,2,4,7-9. Long-acting agents from new antiretroviral classes can provide much-needed treatment options for people living with HIV who are heavily treatment-experienced, and additionally can improve adherence10. Here we describe GS-6207, a small molecule that disrupts the functions of HIV capsid protein and is amenable to long-acting therapy owing to its high potency, low in vivo systemic clearance and slow release kinetics from the subcutaneous injection site. Drawing on X-ray crystallographic information, we designed GS-6207 to bind tightly at a conserved interface between capsid protein monomers, where it interferes with capsid-protein-mediated interactions between proteins that are essential for multiple phases of the viral replication cycle. GS-6207 exhibits antiviral activity at picomolar concentrations against all subtypes of HIV-1 that we tested, and shows high synergy and no cross-resistance with approved antiretroviral drugs. In phase-1 clinical studies, monotherapy with a single subcutaneous dose of GS-6207 (450 mg) resulted in a mean log10-transformed reduction of plasma viral load of 2.2 after 9 days, and showed sustained plasma exposure at antivirally active concentrations for more than 6 months. These results provide clinical validation for therapies that target the functions of HIV capsid protein, and demonstrate the potential of GS-6207 as a long-acting agent to treat or prevent infection with HIV.
Subject(s)
Anti-HIV Agents/pharmacology , Anti-HIV Agents/therapeutic use , Capsid Proteins/antagonists & inhibitors , HIV-1/drug effects , Adolescent , Adult , Anti-HIV Agents/chemistry , Capsid Proteins/genetics , Capsid Proteins/metabolism , Cell Line , Cells, Cultured , Drug Resistance, Viral/genetics , Female , HIV-1/growth & development , Humans , Male , Middle Aged , Models, Molecular , Virus Replication/drug effects , Young AdultABSTRACT
People living with HIV (PLWH) have expressed concern about the life-long burden and stigma associated with taking pills daily and can experience medication fatigue that might lead to suboptimal treatment adherence and the emergence of drug-resistant viral variants, thereby limiting future treatment options1-3. As such, there is strong interest in long-acting antiretroviral (ARV) agents that can be administered less frequently4. Herein, we report GS-CA1, a new archetypal small-molecule HIV capsid inhibitor with exceptional potency against HIV-2 and all major HIV-1 types, including viral variants resistant to the ARVs currently in clinical use. Mechanism-of-action studies indicate that GS-CA1 binds directly to the HIV-1 capsid and interferes with capsid-mediated nuclear import of viral DNA, HIV particle production and ordered capsid assembly. GS-CA1 selects in vitro for unfit GS-CA1-resistant capsid variants that remain fully susceptible to other classes of ARVs. Its high metabolic stability and low solubility enabled sustained drug release in mice following a single subcutaneous dosing. GS-CA1 showed high antiviral efficacy as a long-acting injectable monotherapy in a humanized mouse model of HIV-1 infection, outperforming long-acting rilpivirine. Collectively, these results demonstrate the potential of ultrapotent capsid inhibitors as new long-acting agents for the treatment of HIV-1 infection.
Subject(s)
Anti-HIV Agents/pharmacology , Capsid Proteins/antagonists & inhibitors , HIV Infections/drug therapy , HIV-1/drug effects , Indazoles/pharmacology , Pyridines/pharmacology , Small Molecule Libraries/pharmacology , Animals , Anti-HIV Agents/therapeutic use , Capsid/drug effects , Capsid/metabolism , Capsid Proteins/genetics , DNA, Viral/drug effects , Delayed-Action Preparations , Drug Resistance, Viral/drug effects , HIV Infections/genetics , HIV Infections/virology , HIV-1/genetics , HIV-1/pathogenicity , HIV-2/drug effects , HIV-2/pathogenicity , Humans , Indazoles/therapeutic use , Medication Adherence , Mice , Pyridines/therapeutic useABSTRACT
Direct-acting antiviral inhibitors have revolutionized the treatment of hepatitis C virus (HCV) infected patients. Herein is described the discovery of velpatasvir (VEL, GS-5816), a potent pan-genotypic HCV NS5A inhibitor that is a component of the only approved pan-genotypic single-tablet regimens (STRs) for the cure of HCV infection. VEL combined with sofosbuvir (SOF) is Epclusa®, an STR with 98% cure-rates for genotype 1-6 HCV infected patients. Addition of the pan-genotypic HCV NS3/4A protease inhibitor voxilaprevir to SOF/VEL is the STR Vosevi®, which affords 97% cure-rates for genotype 1-6 HCV patients who have previously failed another treatment regimen.
Subject(s)
Antiviral Agents/pharmacology , Carbamates/pharmacology , Drug Discovery , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/pharmacology , Protease Inhibitors/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Carbamates/chemical synthesis , Carbamates/chemistry , Dose-Response Relationship, Drug , Drug Combinations , Genotype , Hepacivirus/genetics , Heterocyclic Compounds, 4 or More Rings/chemical synthesis , Heterocyclic Compounds, 4 or More Rings/chemistry , Humans , Macrocyclic Compounds/chemistry , Microbial Sensitivity Tests , Molecular Structure , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Sofosbuvir/chemistry , Structure-Activity Relationship , Sulfonamides/chemistry , Tablets/chemistry , Tablets/pharmacology , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolismABSTRACT
Treatment of hepatitis C virus (HCV) infection has been historically challenging due the high viral genetic complexity wherein there are eight distinct genotypes and at least 86 viral subtypes. While HCV NS3/4A protease inhibitors are an established treatment option for genotype 1 infection, limited coverage of genotypes 2 and/or 3 combined with serum alanine transaminase (ALT) elevations for some compounds has limited the broad utility of this therapeutic class. Our discovery efforts were focused on identifying an NS3/4A protease inhibitor with pan-genotypic antiviral activity, improved coverage of resistance associated substitutions, and a decreased risk of hepatotoxicity. Towards this goal, distinct interactions with the conserved catalytic triad of the NS3/4A protease were identified that improved genotype 3 antiviral activity. We further discovered that protein adduct formation strongly correlated with clinical ALT elevation for this therapeutic class. Improving metabolic stability and decreasing protein adduct formation through structural modifications ultimately resulted in voxilaprevir. Voxilaprevir, in combination with sofosbuvir and velpatasvir, has demonstrated pan-genotypic antiviral clinical activity. Furthermore, hepatotoxicity was not observed in Phase 3 clinical trials with voxilaprevir, consistent with our design strategy. Vosevi® (sofosbuvir, velpatasvir, and voxilaprevir) is now an approved pan-genotypic treatment option for the most difficult-to-cure individuals who have previously failed direct acting antiviral therapy.
Subject(s)
Antiviral Agents/pharmacology , Carbamates/chemistry , Drug Discovery , Hepacivirus/drug effects , Heterocyclic Compounds, 4 or More Rings/chemistry , Macrocyclic Compounds/chemistry , Macrocyclic Compounds/pharmacology , Protease Inhibitors/pharmacology , Sofosbuvir/chemistry , Sulfonamides/chemistry , Sulfonamides/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Aminoisobutyric Acids , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Cyclopropanes , Dose-Response Relationship, Drug , Drug Combinations , Hepacivirus/genetics , Humans , Lactams, Macrocyclic , Leucine/analogs & derivatives , Macrocyclic Compounds/chemical synthesis , Microbial Sensitivity Tests , Molecular Structure , Proline/analogs & derivatives , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Quinoxalines , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolismABSTRACT
BACKGROUND: ExteNET showed that 1 year of neratinib, an irreversible pan-HER tyrosine kinase inhibitor, significantly improves 2-year invasive disease-free survival after trastuzumab-based adjuvant therapy in women with HER2-positive breast cancer. We report updated efficacy outcomes from a protocol-defined 5-year follow-up sensitivity analysis and long-term toxicity findings. METHODS: In this ongoing randomised, double-blind, placebo-controlled, phase 3 trial, eligible women aged 18 years or older (≥20 years in Japan) with stage 1-3c (modified to stage 2-3c in February, 2010) operable breast cancer, who had completed neoadjuvant and adjuvant chemotherapy plus trastuzumab with no evidence of disease recurrence or metastatic disease at study entry. Patients who were eligible patients were randomly assigned (1:1) via permuted blocks stratified according to hormone receptor status (hormone receptor-positive vs hormone receptor-negative), nodal status (0 vs 1-3 vs or ≥4 positive nodes), and trastuzumab adjuvant regimen (given sequentially vs concurrently with chemotherapy), then implemented centrally via an interactive voice and web-response system, to receive 1 year of oral neratinib 240 mg/day or matching placebo. Treatment was given continuously for 1 year, unless disease recurrence or new breast cancer, intolerable adverse events, or consent withdrawal occurred. Patients, investigators, and trial funder were masked to treatment allocation. The predefined endpoint of the 5-year analysis was invasive disease-free survival, analysed by intention to treat. ExteNET is registered with ClinicalTrials.gov, number NCT00878709, and is closed to new participants. FINDINGS: Between July 9, 2009, and Oct 24, 2011, 2840 eligible women with early HER2-positive breast cancer were recruited from community-based and academic institutions in 40 countries and randomly assigned to receive neratinib (n=1420) or placebo (n=1420). After a median follow-up of 5·2 years (IQR 2·1-5·3), patients in the neratinib group had significantly fewer invasive disease-free survival events than those in the placebo group (116 vs 163 events; stratified hazard ratio 0·73, 95% CI 0·57-0·92, p=0·0083). The 5-year invasive disease-free survival was 90·2% (95% CI 88·3-91·8) in the neratinib group and 87·7% (85·7-89·4) in the placebo group. Without diarrhoea prophylaxis, the most common grade 3-4 adverse events in the neratinib group, compared with the placebo group, were diarrhoea (561 [40%] grade 3 and one [<1%] grade 4 with neratinib vs 23 [2%] grade 3 with placebo), vomiting (grade 3: 47 [3%] vs five [<1%]), and nausea (grade 3: 26 [2%] vs two [<1%]). Treatment-emergent serious adverse events occurred in 103 (7%) women in the neratinib group and 85 (6%) women in the placebo group. No evidence of increased risk of long-term toxicity or long-term adverse consequences of neratinib-associated diarrhoea were identified with neratinib compared with placebo. INTERPRETATION: At the 5-year follow-up, 1 year of extended adjuvant therapy with neratinib, administered after chemotherapy and trastuzumab, significantly reduced the proportion of clinically relevant breast cancer relapses-ie, those that might lead to death, such as distant and locoregional relapses outside the preserved breast-without increasing the risk of long-term toxicity. An analysis of overall survival is planned after 248 events. FUNDING: Wyeth, Pfizer, and Puma Biotechnology.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Breast Neoplasms/drug therapy , Quinolines/administration & dosage , Receptor, ErbB-2/metabolism , Trastuzumab/administration & dosage , Administration, Oral , Adult , Antibodies, Monoclonal, Humanized/adverse effects , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Breast Neoplasms/mortality , Breast Neoplasms/pathology , Breast Neoplasms/surgery , Chemotherapy, Adjuvant , Disease-Free Survival , Dose-Response Relationship, Drug , Double-Blind Method , Drug Administration Schedule , Female , Follow-Up Studies , Humans , Japan , Kaplan-Meier Estimate , Mastectomy/methods , Middle Aged , Neoplasm Invasiveness/pathology , Neoplasm Staging , Proportional Hazards Models , Quinolines/adverse effects , Risk Assessment , Survival Analysis , Time Factors , Trastuzumab/adverse effects , Treatment OutcomeABSTRACT
Preclinical characterization of velpatasvir (VEL; GS-5816), an inhibitor of the hepatitis C virus (HCV) NS5A protein, demonstrated that it has favorable in vitro and in vivo properties, including potent antiviral activity against hepatitis C virus genotype 1 to 6 replicons, good metabolic stability, low systemic clearance, and adequate bioavailability and physicochemical properties, to warrant clinical evaluation. The phase 1 (first-in-human) study evaluated the safety, tolerability, and pharmacokinetics of VEL in healthy human subjects following administration of single and multiple (n = 7) once-daily ascending doses and of VEL in the presence and absence of food. Following administration of single and multiple doses, VEL was safe and well tolerated when administered at up to 450 mg and when administered with food. The pharmacokinetic behavior of VEL observed in humans was generally in agreement with that seen during preclinical characterization. Following administration of multiple doses, VEL trough concentrations were significantly greater than the protein-adjusted half-maximal (50%) effective concentration of VEL against HCV genotype 1 to 6 replicons at all evaluated doses greater than 5 mg. The pharmacokinetics of VEL were not significantly affected by administration with food. Collectively, the results of this study support the further clinical investigation of VEL administered once daily as part of a regimen with other pangenotypic direct-acting antivirals for the treatment of HCV infection.
Subject(s)
Antiviral Agents/therapeutic use , Carbamates/pharmacokinetics , Carbamates/therapeutic use , Hepacivirus/drug effects , Hepatitis C/drug therapy , Heterocyclic Compounds, 4 or More Rings/pharmacokinetics , Heterocyclic Compounds, 4 or More Rings/therapeutic use , Viral Nonstructural Proteins/antagonists & inhibitors , Adult , Animals , Antiviral Agents/adverse effects , Carbamates/adverse effects , Dogs , Female , Healthy Volunteers , Hepatitis C/virology , Heterocyclic Compounds, 4 or More Rings/adverse effects , Humans , Macaca fascicularis , Male , Microsomes, Liver/metabolism , Middle Aged , Rats , Rats, Sprague-Dawley , Virus Replication/drug effects , Young AdultABSTRACT
Velpatasvir (VEL, GS-5816) is a novel pan-genotypic hepatitis C virus (HCV) nonstructural protein 5A (NS5A) inhibitor with activity against genotype 1 (GT1) to GT6 HCV replicons. In a phase 1b 3-day monotherapy study, patients treated with a 150-mg dose of GS-5816 had a mean maximal HCV RNA decline of ≥3.3 log10 IU/ml in GT1a, -1b, -2, -3, and -4. This report characterizes virologic resistance to VEL in these patients. NS5A resistance-associated substitutions (RASs) were detected by deep sequencing (1% cutoff) pretreatment in 22/70 patients, i.e., 10/35 (29%) patients with GT1a, 1/8 (13%) with GT1b, 4/8 (50.0%) with GT2, 5/17 (29.4%) with GT3, and 2/2 (100.0%) with GT4. In GT1a and GT3 patients, pretreatment RASs were associated with a slightly reduced HCV RNA response compared to that of patients without pretreatment RASs; among patients with GT1b, GT2, and GT4, no significant difference in response was observed in those with or without pretreatment RASs. Following treatment, the pattern of emergent RASs was more complex for GT1a than for the other genotypes. In GT1a, substitutions emerged at positions M28, Q30, L31, P32, H58, E92, and Y93, with the most prevalent substitutions at positions Y93, M28, and L31. RASs were observed at two positions in GT1b and GT2 (Y93 and L31), three positions in GT3 (Y93, L31, and E92), and four positions in GT4 (L28, M31, P32L, and Y93). RASs that were present pretreatment persisted through the 48-week follow-up period; however, RASs emerging during treatment were more likely to decline both in prevalence and in frequency within the viral population during follow-up. (This study has been registered at ClinicalTrials.gov under registration no. NCT01740791.).
Subject(s)
Antiviral Agents/therapeutic use , Carbamates/therapeutic use , Drug Resistance, Viral/genetics , Hepatitis C, Chronic/drug therapy , Heterocyclic Compounds, 4 or More Rings/therapeutic use , RNA, Viral/genetics , Viral Nonstructural Proteins/genetics , Amino Acid Substitution , Double-Blind Method , Drug Administration Schedule , Gene Expression , Genotype , Hepacivirus/drug effects , Hepacivirus/genetics , Hepacivirus/growth & development , Hepatitis C, Chronic/virology , Humans , Mutation , RNA, Viral/antagonists & inhibitors , Viral Nonstructural Proteins/antagonists & inhibitorsABSTRACT
UNLABELLED: A clinical laboratory evaluation of an intrinsic fluorescence spectroscopy (IFS)-based identification system paired to a BacT/Alert Virtuo microbial detection system (bioMérieux, Inc., Durham, NC) was performed to assess the potential for fully automated identification of positive blood cultures. The prototype IFS system incorporates a novel method combining a simple microbial purification procedure with rapid in situ identification via spectroscopy. Results were available within 15 min of a bottle signaling positive and required no manual intervention. Among cultures positive for organisms contained within the database and producing acceptable spectra, 75 of 88 (85.2%) and 79 of 88 (89.8%) were correctly identified to the species and genus level, respectively. These results are similar to the performance of existing rapid methods. IMPORTANCE: A fully automated research platform was developed to identify microbial growth from positive blood cultures in <15 min. Because of the automated format, results can be generated during all shifts, with or without staffing, which in turn could promote more timely administration of target antimicrobial therapy.
Subject(s)
Automation/methods , Bacteremia/microbiology , Bacteria/isolation & purification , Blood Culture/methods , Spectrometry, Fluorescence/methods , Automation/instrumentation , Bacteremia/diagnosis , Bacteria/classification , Bacteria/growth & development , Blood Culture/instrumentation , HumansABSTRACT
Ledipasvir (LDV; GS-5885), a component of Harvoni (a fixed-dose combination of LDV with sofosbuvir [SOF]), is approved to treat chronic hepatitis C virus (HCV) infection. Here, we report key preclinical antiviral properties of LDV, including in vitro potency, in vitro resistance profile, and activity in combination with other anti-HCV agents. LDV has picomolar antiviral activity against genotype 1a and genotype 1b replicons with 50% effective concentration (EC50) values of 0.031 nM and 0.004 nM, respectively. LDV is also active against HCV genotypes 4a, 4d, 5a, and 6a with EC50 values of 0.11 to 1.1 nM. LDV has relatively less in vitro antiviral activity against genotypes 2a, 2b, 3a, and 6e, with EC50 values of 16 to 530 nM. In vitro resistance selection with LDV identified the single Y93H and Q30E resistance-associated variants (RAVs) in the NS5A gene; these RAVs were also observed in patients after a 3-day monotherapy treatment. In vitro antiviral combination studies indicate that LDV has additive to moderately synergistic antiviral activity when combined with other classes of HCV direct-acting antiviral (DAA) agents, including NS3/4A protease inhibitors and the nucleotide NS5B polymerase inhibitor SOF. Furthermore, LDV is active against known NS3 protease and NS5B polymerase inhibitor RAVs with EC50 values equivalent to those for the wild type.
Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , Fluorenes/pharmacology , Hepacivirus/drug effects , Hepatitis C, Chronic/drug therapy , Viral Nonstructural Proteins/antagonists & inhibitors , Carrier Proteins/antagonists & inhibitors , Cell Line, Tumor , Drug Combinations , Drug Resistance, Viral/genetics , Drug Synergism , Genotype , HeLa Cells , Hepacivirus/genetics , Humans , Intracellular Signaling Peptides and Proteins , Microbial Sensitivity Tests , Sofosbuvir/pharmacologyABSTRACT
Ledipasvir, a direct acting antiviral agent (DAA) targeting the Hepatitis C Virus NS5A protein, exhibits picomolar activity in replicon cells. While its mechanism of action is unclear, mutations that confer resistance to ledipasvir in HCV replicon cells are located in NS5A, suggesting that NS5A is the direct target of ledipasvir. To date co-precipitation and cross-linking experiments in replicon or NS5A transfected cells have not conclusively shown a direct, specific interaction between NS5A and ledipasvir. Using recombinant, full length NS5A, we show that ledipasvir binds directly, with high affinity and specificity, to NS5A. Ledipasvir binding to recombinant NS5A is saturable with a dissociation constant in the low nanomolar range. A mutant form of NS5A (Y93H) that confers resistance to ledipasvir shows diminished binding to ledipasvir. The current study shows that ledipasvir inhibits NS5A through direct binding and that resistance to ledipasvir is the result of a reduction in binding affinity to NS5A mutants.
Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , Drug Resistance, Viral/genetics , Fluorenes/pharmacology , Hepacivirus/drug effects , Mutation , Viral Nonstructural Proteins/genetics , Amino Acid Sequence , Antiviral Agents/chemistry , Benzimidazoles/chemistry , Cell Line, Tumor , Fluorenes/chemistry , Hepacivirus/genetics , Hepacivirus/metabolism , Hepatocytes/drug effects , Hepatocytes/pathology , Hepatocytes/virology , Humans , Kinetics , Molecular Sequence Data , Protein Binding , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Replicon , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism , Virus ReplicationABSTRACT
A new class of highly potent NS5A inhibitors with an unsymmetric benzimidazole-difluorofluorene-imidazole core and distal [2.2.1]azabicyclic ring system was discovered. Optimization of antiviral potency and pharmacokinetics led to the identification of 39 (ledipasvir, GS-5885). Compound 39 (GT1a replicon EC50 = 31 pM) has an extended plasma half-life of 37-45 h in healthy volunteers and produces a rapid >3 log viral load reduction in monotherapy at oral doses of 3 mg or greater with once-daily dosing in genotype 1a HCV-infected patients. 39 has been shown to be safe and efficacious, with SVR12 rates up to 100% when used in combination with direct-acting antivirals having complementary mechanisms.
Subject(s)
Antiviral Agents/therapeutic use , Benzimidazoles/therapeutic use , Fluorenes/therapeutic use , Hepatitis C/drug therapy , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Animals , Antiviral Agents/administration & dosage , Antiviral Agents/pharmacokinetics , Base Sequence , Benzimidazoles/pharmacokinetics , Benzimidazoles/pharmacology , DNA Primers , Double-Blind Method , Fluorenes/pharmacokinetics , Fluorenes/pharmacology , Half-Life , Humans , Macaca fascicularis , Male , Placebos , Rats , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
UNLABELLED: A positive blood culture is a critical result that requires prompt identification of the causative agent. This article describes a simple method to identify microorganisms from positive blood culture broth within the time taken to perform a Gram stain (<20 min). The method is based on intrinsic fluorescence spectroscopy (IFS) of whole cells and required development of a selective lysis buffer, aqueous density cushion, optical microcentrifuge tube, and reference database. A total of 1,121 monomicrobial-positive broth samples from 751 strains were analyzed to build a database representing 37 of the most commonly encountered species in bloodstream infections or present as contaminants. A multistage algorithm correctly classified 99.6% of unknown samples to the Gram level, 99.3% to the family level, and 96.5% to the species level. There were no incorrect results given at the Gram or family classification levels, while 0.8% of results were discordant at the species level. In 8/9 incorrect species results, the misidentified isolate was assigned to a species of the same genus. This unique combination of selective lysis, density centrifugation, and IFS can rapidly identify the most common microbial species present in positive blood cultures. Faster identification of the etiologic agent may benefit the clinical management of sepsis. Further evaluation is now warranted to determine the performance of the method using clinical blood culture specimens. IMPORTANCE: Physicians often require the identity of the infective agent in order to make life-saving adjustments to empirical therapy or to switch to less expensive and/or more targeted antimicrobials. However, standard identification procedures take up to 2 days after a blood culture is signaled positive, and even most rapid molecular techniques take several hours to provide a result. Other techniques are faster (e.g., matrix-assisted laser desorption ionization-time of flight [MALDI-TOF] mass spectrometry) but require time-consuming manual processing steps and expensive equipment. There remains a clear need for a simple, inexpensive method to rapidly identify microorganisms directly from positive blood cultures. The promising new method described in this research article can identify microorganisms in minutes by optical spectroscopy, thus permitting the lab to simultaneously report the presence of a positive blood culture and the organism's identity.
Subject(s)
Bacteremia/diagnosis , Bacteria/isolation & purification , Blood/microbiology , Fungemia/diagnosis , Fungi/isolation & purification , Microbiological Techniques/methods , Spectrometry, Fluorescence/methods , Bacteremia/microbiology , Bacteria/chemistry , Bacteria/classification , Fungemia/microbiology , Fungi/chemistry , Fungi/classification , Humans , Sensitivity and Specificity , Specimen Handling/methodsABSTRACT
PURPOSE: Evidence suggests that expressing emotions related to cancer and receiving interpersonal support can promote psychological and physical health in women diagnosed with breast cancer. However, adaptive expression of feelings and communication with one's social network can pose challenges for patients with cancer. We report on a randomized controlled trial of an intervention, Project Connect Online, for patients with breast cancer to create personal Web sites to chronicle their experience and communicate with their social network. PATIENTS AND METHODS: Women (N = 88) diagnosed with breast cancer (any stage, any interval since diagnosis) were randomly assigned to participate in a 3-hour workshop for hands-on creation of personal Web sites with a follow-up call to facilitate Web site use, or to a waiting-list control. Assessed before randomization and 6 months after the intervention, dependent variables included depressive symptoms, positive and negative mood, cancer-related intrusive thoughts, and perceived cancer-related benefits in life appreciation and strengthened relationships. RESULTS: Relative to control participants, women randomly assigned to Project Connect Online evidenced significant benefit 6 months later on depressive symptoms, positive mood, and life appreciation, but not negative mood, perceived strengthened relationships, or intrusive thoughts. Treatment status moderated the intervention effects, such that women currently undergoing medical treatment for cancer benefitted significantly more from the intervention on depressive symptoms and positive mood than did women not receiving treatment. CONCLUSION: Findings suggest the promise of an intervention to facilitate the ability of women diagnosed with breast cancer to chronicle their experience and communicate with their social network via the Internet.
Subject(s)
Breast Neoplasms/psychology , Communication , Internet , Adult , Aged , Female , Humans , Middle Aged , Social Support , Treatment OutcomeABSTRACT
Tegobuvir (TGV) is a novel non-nucleoside inhibitor (NNI) of HCV RNA replication with demonstrated antiviral activity in patients with genotype 1 chronic HCV infection. The mechanism of action of TGV has not been clearly defined despite the identification of resistance mutations mapping to the NS5B polymerase region. TGV does not inhibit NS5B enzymatic activity in biochemical assays in vitro, suggesting a more complex antiviral mechanism with cellular components. Here, we demonstrate that TGV exerts anti-HCV activity utilizing a unique chemical activation and subsequent direct interaction with the NS5B protein. Treatment of HCV subgenomic replicon cells with TGV results in a modified form of NS5B with a distinctly altered mobility on a SDS-PAGE gel. Further analysis reveals that the aberrantly migrating NS5B species contains the inhibitor molecule. Formation of this complex does not require the presence of any other HCV proteins. The intensity of the aberrantly migrating NS5B species is strongly dependent on cellular glutathione levels as well as CYP 1A activity. Furthermore analysis of NS5B protein purified from a heterologous expression system treated with TGV by mass spectrometry suggests that TGV undergoes a CYP- mediated intracellular activation step and the resulting metabolite, after forming a glutathione conjugate, directly and specifically interacts with NS5B. Taken together, these data demonstrate that upon metabolic activation TGV is a specific, covalent inhibitor of the HCV NS5B polymerase and is mechanistically distinct from other classes of the non-nucleoside inhibitors (NNI) of the viral polymerase.
Subject(s)
Antiviral Agents/pharmacology , Hepacivirus/drug effects , Purines/pharmacology , Pyridazines/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Base Sequence , Blotting, Western , Cell Line , DNA Primers , Humans , Mass Spectrometry , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
BACKGROUND & AIMS: GS-5885 is an inhibitor of the hepatitis C virus (HCV) NS5A protein and exhibits potent suppression of genotype 1 HCV replicons. The safety, tolerability, pharmacokinetics, antiviral activity, and resistance profile of once-daily GS-5885 doses of 1-90 mg were evaluated in patients with chronic genotype 1 HCV. METHODS: Genotype 1 HCV-infected patients were randomized to 3 days of once-daily (QD) dosing with placebo (n=12) or GS-5885 1 mg (n=10), 3 mg (n=10), 10 mg (n=20), 30 mg (n=10), or 90 mg (n=10). Plasma samples for pharmacokinetics, HCV RNA, and NS5A sequencing were collected through day 14. RESULTS: GS-5885 was well tolerated and resulted in median maximal reductions in HCV RNA ranging from 2.3 log(10) IU/ml (1 mg QD) to 3.3 log(10) IU/ml (10 mg QD in genotype 1b and 30 mg QD). E(max) modeling indicated GS-5885 30 mg was associated with>95% of maximal antiviral response to HCV genotype 1a. HCV RNA reductions were generally more sustained among patients with genotype 1b vs. 1a. Three of 60 patients had a reduced response and harbored NS5A-resistant virus at baseline. NS5A sequencing identified residues 30 and 31 in genotype 1a, and 93 in genotype 1b as the predominant sites of mutation following GS-5885 dosing. Plasma pharmacokinetics was consistent with QD dosing. CONCLUSIONS: During 3 days of monotherapy, low doses of GS-5885 demonstrated significant antiviral activity in genotype 1a and 1b HCV-infected patients. GS-5885 is currently being evaluated in combination with direct antiviral regimens with and without peginterferon.