Introduction and Objectives: In clinical trials, patients with hepatitis C virus (HCV) genotype (GT)1a infection and baseline resistance-associated substitutions (RASs) at amino acid positions 28, 30, 31, or 93 receiving elbasvir/grazoprevir for 12 weeks achieved lower rates of sustained virologic response (SVR) than those without baseline RASs. SVR rates in patients with RASs were improved when elbasvir/grazoprevir treatment duration was extended from 12 to 16 weeks and administered concomitantly with ribavirin.Materials and Methods: This was a retrospective, observational analysis using electronic health record abstraction. Patients with HCV GT1a infection and RASs at positions 28, 30, 31, or 93 who were prescribed 16 weeks of elbasvir/grazoprevir and >= 1 prescription for ribavirin were included. SVR was defined as HCV RNA below the lower limit of quantification >= 70 days after end of treatment.Results: The primary analysis included patients with baseline RASs at positions 30, 31, or 93 (n = 76); a sec-ondary analysis included patients with RASs at positions 28, 30, 31, or 93 (n = 93). SVR was achieved by 77.6% (59/76) of patients in the primary analysis and 80.6% (75/93) of those in the secondary analysis. Of the 18 (19.4%) patients in the secondary cohort who failed to achieve SVR, 8 relapsed (4 with treatment -emer-gent NS5A substitutions) and 10 did not have viral sequencing to distinguish relapse from reinfection.Conclusions: This analysis highlights the opportunities in leveraging real-world data to further understand treatment outcomes in smaller, discrete subgroups of patients with HCV infection who cannot be thoroughly evaluated in clinical trials.(c) 2023 Merck Sharp & Dohme LLC., a subsidiary Merck & Co., Inc., Rahway, NJ, USA and The Author(s). Pub-lished by Elsevier Spain. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Standard-of-care HIV pre-exposure prophylaxis (PrEP) is highly efficacious, but uptake of and persistence on a daily oral pill is low in many settings. Evaluation of alternate PrEP products will require innovation to avoid the unpractically large sample sizes in noninferiority trials. We propose estimating HIV incidence in people not on PrEP as an external counterfactual to which on-PrEP incidence in trial subjects can be compared. HIV recent infection testing algorithms (RITAs), such as the limiting antigen avidity assay plus viral load used on specimens from untreated HIV positive people identified during screening, is one possible approach. Its feasibility is partly dependent on the sample size needed to ensure adequate power, which is impacted by RITA performance, the number of recent infections identified, the expected efficacy of the intervention, and other factors. Screening sample sizes to support detection of an 80% reduction in incidence for 3 key populations are more modest, and comparable to the number of participants in recent phase III PrEP trials. Sample sizes would be significantly larger in populations with lower incidence, where the false recency rate is higher or if PrEP efficacy is expected to be lower. Our proposed counterfactual approach appears to be feasible, offers high statistical power, and is nearly contemporaneous with the on-PrEP population. It will be important to monitor the performance of this approach during new product development for HIV prevention. If successful, it could be a model for preventive HIV vaccines and prevention of other infectious diseases.

BACKGROUND:Islatravir (MK-8591) is a nucleoside reverse transcriptase translocation inhibitor in development for treatment and prevention of HIV-1. We present efficacy and safety data for islatravir and doravirine (DOR) through 96 weeks of the phase 2b trial (NCT03272347).METHODS:In this randomized, double-blind, dose-ranging trial, participants initially received islatravir (0.25, 0.75, or 2.25 mg) with doravirine (100 mg) and lamivudine (3TC, 300 mg) or a fixed-dose combination of doravirine, 3TC, and tenofovir disoproxil fumarate (DOR/3TC/TDF) daily. Beginning at week 24, participants receiving islatravir stopped 3TC if HIV-1 RNA from the prior visit was <50 copies per milliliter and continued taking the assigned islatravir dose (still blinded) with doravirine. All islatravir groups transitioned to open-label use of 0.75 mg between weeks 60 and 84. Efficacy end points at week 96 included the proportion of participants maintaining HIV-1 RNA of <50 copies per milliliter (FDA Snapshot). Safety was assessed by adverse event (AE) reporting.RESULTS:One hundred twenty-one treatment-naive participants received the study drugs and were included in the analyses. Through week 96, HIV-1 RNA<50 copies per milliliter was maintained in 86.2% (25/29), 90.0% (27/30), and 67.7% (21/31) of participants in the 0.25-, 0.75-, and 2.25-mg islatravir groups, respectively, 81.1% (73/90) of the combined islatravir group, and 80.6% (25/31) of the DOR/3TC/TDF group. One participant in the 2.25-mg islatravir group had Protocol-Defined Virologic Failure after week 48. Drug-related AE rates were higher for DOR/3TC/TDF participants (22.6%) compared with islatravir (combined 7.8%). Two participants (2.2%) receiving islatravir with doravirine and one (3.2%) receiving DOR/3TC/TDF discontinued because of an AE.CONCLUSIONS:Treatment regimens containing islatravir and doravirine maintained viral suppression through week 96 and were well tolerated regardless of dose.

BACKGROUND:Hepatitis C virus (HCV) reinfection after successful treatment may reduce the benefits of cure among people who inject drugs. OBJECTIVE:To evaluate the rate of HCV reinfection for 3 years after successful treatment among people receiving opioid agonist therapy (OAT). DESIGN:A 3-year, long-term, extension study of persons enrolled in the CO-STAR (Hepatitis C Patients on Opioid Substitution Therapy Antiviral Response) study (ClinicalTrials.gov: NCT02105688). SETTING:55 clinical trial sites in 13 countries. PATIENTS:Aged 18 years and older with chronic HCV infection with genotypes 1, 4, or 6 receiving stable OAT. INTERVENTION:No treatments were administered. MEASUREMENTS:Serum samples were assessed for HCV reinfection. Urine drug screening was performed. RESULTS:Among 296 participants who received treatment, 286 were evaluable for reinfection and 199 were enrolled in the long-term extension study. The rate of HCV reinfection was 1.7 [95% CI, 0.8 to 3.0] per 100 person-years; 604 person-years of follow-up). A higher rate of reinfection was seen among people with recent injecting drug use (1.9 [95% CI, 0.5 to 4.8] per 100 person-years; 212 person-years). Ongoing drug use and injecting drug use were reported by 59% and 21% of participants, respectively, at the 6-month follow-up visit and remained stable during 3 years of follow-up. LIMITATIONS:Participants were required to be 80% adherent to OAT at baseline and may represent a population with higher stability and lower risk for HCV reinfection. Rate of reinfection may be underestimated because all participants did not continue in the long-term extension study; whether participants who discontinued were at higher risk for reinfection is unknown. CONCLUSION:Reinfection with HCV was low but was highest in the first 24 weeks after treatment completion and among people with ongoing injecting drug use and needle-syringe sharing. PRIMARY FUNDING SOURCE:Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.

Background: Islatravir (MK-8591) is a deoxyadenosine analog in development for the treatment and prevention of HIV-1 infection. An islatravir-eluting implant could provide an additional option for pre-exposure prophylaxis (PrEP). Setting: Previous data support a threshold islatravir triphosphate concentration for PrEP of 0.05 pmol/106 cells in peripheral blood mononuclear cells. Prototype islatravir-eluting implants were previously studied to establish general tolerability and pharmacokinetics (PKs) of islatravir relative to the threshold level. Methods: In this randomized, double-blind, placebo-controlled, phase 1 trial, a next-generation radiopaque islatravir-eluting implant (48 mg, 52 mg, or 56 mg) or placebo implant was placed for a duration of 12 weeks in participants at low risk of HIV infection. Safety and tolerability, as well as PK for islatravir parent and islatravir triphosphate from plasma and peripheral blood mononuclear cells, were assessed throughout placement and 8 weeks after removal. Results: In total, 36 participants (8 active and 4 placebo per dose arm) were enrolled and completed this study. Implants were generally well tolerated, with no discontinuations due to an adverse event, and no clear dose-dependence in implant-related adverse events. No clinically meaningful relationships were observed for changes in laboratory values, vital signs, or electrocardiogram assessments. Mean islatravir triphosphate levels at day 85 (0.101–0.561 pmol/106 cells) were above the PK threshold for all dose levels. Conclusion: Islatravir administered using a subdermal implant has the potential to be an effective and well-tolerated method for administering PrEP to individuals at risk of acquiring HIV-1.

Background Islatravir is a nucleoside reverse transcriptase translocation inhibitor in development for the treatment and prevention of HIV-1 infection. We aimed to assess the efficacy and safety of islatravir-based regimens for the treatment of HIV-1. Methods We did a phase 2b, randomised, double-blind, comparator-controlled, dose-ranging trial at 24 clinics or hospitals in four countries (Chile, France, the UK, and the USA). Treatment-naive adults (>= 18 years) with plasma HIV-1 RNA concentrations of at least 1000 copies per mL, CD4 T-cell counts of at least 200 cells per mL, and a calculated creatinine clearance of at least 50 mL/min (all within 60 days before study treatment) were eligible for inclusion. Participants were randomly assigned (1:1:1:1) with a block size of four via an interactive voice and web response system to receive oral treatment with one of three doses of islatravir (0.25 mg, 0.75 mg, or 2.25 mg) plus doravirine (100 mg) and lamivudine (300 mg) or to doravirine (100 mg) plus lamivudine (300 mg) plus tenofovir disoproxil fumarate (TDF; 300 mg) once daily with placebo (part 1). Treatment groups were stratified according to screening HIV-1 RNA concentration (<= 100 000 copies per mL or >100 000 copies per mL). After at least 24 weeks of treatment, participants taking islatravir who achieved an HIV-1 RNA concentration lower than 50 copies per mL switched to a two-drug regimen of islatravir and doravirine (part 2). All participants and study investigators were masked to treatment in part 1; in part 2, the islatravir dose was masked to all participants and investigators, but the other drugs were given open label. The primary efficacy outcomes were the proportions of participants with an HIV-1 RNA concentration lower than 50 copies per mL at weeks 24 and 48 (US Food and Drug Administration snapshot approach). The primary safety outcomes were the number of participants experiencing adverse events and the number of participants discontinuing study drug owing to adverse events. All participants who received at least one dose of any study drug were included in the analyses. This trial is ongoing, but closed to enrolment of new participants; herein, we report study findings through 48 weeks of treatment. This trial is registered with ClinicalTrials.gov, NCT03272347. Findings Between Nov 27, 2017, and April 25, 2019, 121 participants (mean age 31 years [SD 10.9], 112 [93%] male, 92 [76%] white, 27 [22%] with HIV-1 RNA concentration >100 000 copies per mL) were randomly assigned: 29 to the 0.25 mg, 30 to the 0.75 mg, and 31 to the 2.25 mg islatravir groups, and 31 to the doravirine, lamivudine, and TDF group. At week 24, 26 (90%) of 29 participants in the 0.25 mg islatravir group, 30 (100%) of 30 in the 0.75 mg islatravir group, and 27 (87%) of 31 in the 2.25 mg islatravir group achieved HIV-1 RNA concentrations lower than 50 copies per mL compared with 27 (87%) of 31 in the doravirine plus lamivudine plus TDF group (difference 2.8%, 95% CI -14.9 to 20.4, for the 0.25 mg islatravir group; 12.9%, -1.6 to 27.5, for the 0.75 mg islatravir group; and 0.3%, -17.9 to 18.5, for the 2.25 mg islatravir group). At week 48, these data were 26 (90%) of 29 in the 0.25 mg islatravir group, 27 (90%) of 30 in the 0.75 mg islatravir group, and 24 (77%) of 31 in the 2.25 mg islatravir group compared with 26 (84%) of 31 in the doravirine plus lamivudine plus TDF group (difference 6.1%, 95% CI -12.4 to 24.4, for the 0.25 mg islatravir group; 6.2%, -12.2 to 24.6, for the 0.75 mg islatravir group; and -6.1%, -27.1 to 14.8, for the 2.75 mg islatravir group). 66 (73%) of participants in the islatravir groups combined and 24 (77%) of those in the doravirine plus lamivudine plus TDF group reported at least one adverse event. Two participants in the 2.25 mg islatravir group and one participant in the doravirine plus lamivudine plus TDF group discontinued owing to an adverse event. No deaths were reported up to week 48. Interpretation Treatment regimens containing islatravir and doravirine showed antiviral efficacy and were well tolerated regardless of dose. Doravirine in combination with islatravir has the potential to be a potent two-drug regimen that warrants further clinical development.

Background: In the United States, the number of new cases of hepatitis C virus infection has risen in recent years, driven largely by transmission among young white adults in their 20s and 30s. Herein, we report an integrated analysis of participants with hepatitis C virus infection aged ≤35 years from 12 phase II/III clinical trials of elbasvir/grazoprevir.Methods: Treatment-naive and -experienced adults with hepatitis C virus genotype 1 or 4 infection received elbasvir (50 mg/day)/grazoprevir (100 mg/day) for 12 weeks without ribavirin. Analyses were stratified according to participant age (≤35 years vs >35 years). The primary endpoint was sustained virologic response (hepatitis C virus RNA < lower limit of quantitation at 12 weeks after completion of therapy).Results: Sustained virologic response was achieved by 98.9% (271/274) of participants aged ≤35 years and by 96.9% (2093/2160) aged >35 years. Three participants aged ≤35 years with genotype 1b infection relapsed. Eight participants with genotype 1a infection and baseline non-structural protein 5 A resistance-associated substitutions achieved sustained virologic response. Similarly, all 85 participants aged ≤35 years with genotype 1a infection and no baseline non-structural protein 5 A resistance-associated substitutions achieved sustained virologic response. Safety was favorable, with the incidence of drug-related adverse events similar in younger and older participants (30.1% vs 30.6%). One participant (0.4%) aged ≤35 years and 15 participants (0.7%) aged >35 years discontinued treatment owing to adverse events.Conclusions: Elbasvir/grazoprevir for 12 weeks was safe and highly effective in participants aged ≤35 years with hepatitis C virus genotype 1 or 4 infection.

PURPOSE:Hepatitis C virus (HCV) infection is a major healthcare concern in Russia, where almost 5 million individuals are viremic. Elbasvir/grazoprevir is a fixed-dose combination therapy for the treatment of HCV genotype 1 and genotype 4 infection. The present analysis aimed to assess the safety and efficacy of elbasvir/grazoprevir in individuals with HCV infection enrolled at Russian study sites in the C-CORAL study.PATIENTS AND METHODS:C-CORAL (Protocol PN-5172-067; NCT02251990) was a Phase 3, placebo-controlled, double-blind study conducted throughout Asia and Russia. Treatment-naive participants with chronic HCV infection were randomly assigned to receive immediate or deferred treatment with elbasvir 50 mg/grazoprevir 100 mg once daily for 12 weeks. Participants in the immediate-treatment group received elbasvir/grazoprevir for 12 weeks, and those in the deferred-treatment group received placebo for 12 weeks, followed by open-label elbasvir/grazoprevir for 12 weeks. The primary endpoint was sustained virologic response at 12 weeks after completion of therapy (SVR12).RESULTS:One hundred and nineteen Russian participants were randomized (immediate-treatment group, n=88; deferred-treatment group, n=31). Most participants were white (99%) with HCV genotype 1b infection (97%) and mild-to-moderate (F0-F2) fibrosis (70%). SVR12 was achieved by 98.9% participants in the immediate-treatment group and by 100% of those receiving deferred elbasvir/grazoprevir in the deferred-treatment group. One participant relapsed with nonstructural protein 5A (NS5A) L28M and Y93H resistance-associated substitutions at baseline and at time of failure. Drug-related adverse events were reported by 19% of participants receiving elbasvir/grazoprevir in the immediate-treatment group and by 16% of those receiving placebo in the deferred-treatment group. No serious adverse event or deaths occurred, and no participant discontinued treatment owing to an adverse event.CONCLUSION:Elbasvir/grazoprevir for 12 weeks was highly effective in treatment-naive Russian individuals with HCV genotype 1b infection.

Cannabinoid receptor 1 (CB1) is a key drug target for a number of diseases, including metabolic syndromes and neuropathic pain. Most of the typical cannabinoid ligands provoke psychotropic side effects that impair their therapeutic utility. As of today, it is not yet clearly known which structural features of cannabinoid ligands determine a preference toward specific signaling pathways. Distinct bioassays are typically used to elucidate signaling preferences. However, these are often based on different cell lines and use different principles and/or read-outs, which makes straightforward assessment of "ligand bias" difficult. Within this context, this study is the first to investigate ligand bias among synthetic cannabinoid receptor agonists (SCRAs) in as closely analogous conditions as possible, by applying a new functional complementation-based assay panel to assess the recruitment of Gai protein or beta-arrestin2 to CB1. In a panel of 21 SCRAs, chosen to cover a broad diversity in chemical structures, distinct, although often subtle, preferences toward specific signaling pathways were observed. Relative to CP55940, here considered as a "balanced" reference agonist, most of the selected SCRAs (e.g., 5F-APINACA, CUMYL-PEGACLONE, among others) displayed preferred signaling through the beta-arrestin2 pathway, whereas MMB-CHMICA could serve as a potential "balanced" agonist. Interestingly, EG-018 was the only SCRA showing a significant (10-fold) preference toward G protein over beta-arrestin2 recruitment. While it is currently unclear what this exactly means in terms of abuse potential and/or toxicity, the approach proposed here may allow construction of a knowledge base that in the end may allow better insight into the structure-"functional" activity relationship of these compounds. This may aid the development of new therapeutics with less unwanted psychoactive effects.

Various oral interferon- and ribavirin-free regimens are becoming available to treat chronic hepatitis C virus (HCV) infection. This phase 3 trial evaluates the effectiveness and tolerability of a ...

Konstantin Zhdanov Vasily Isakov 2 Eduard Burnevich Svetlana Kizhlo Igor Bakulin 5 Vadim Pokrovsky Liwen Liang Peggy Hwang Rohit Talwani Barbara A Haber 7 Michael N Robertson 1Military Medical Academy n.a. S.M. Kirov, St. Petersburg, Russia; 2Department of Gastroenterology & Hepatology, Federal Research Centre of Nutrition, Biotechnology and Food Safety, Moscow, Russia; 3I.M. Sechenov First Moscow State Medical University, Moscow, Russia; 4City Center for AIDS and Infectious Diseases Treatment and Prophylaxis, St. Petersburg, Russia; 5I.I. Mechnikov North-Western State Medical University of the Ministry of Health of the Russian Federation, St. Petersburg, Russia; 6Department of AIDS, Central Research Institute of Epidemiology, Moscow, Russia; 7Merck & Co., Inc., Kenilworth, NJ, USA Purpose: Hepatitis C virus (HCV) infection is a major healthcare concern in Russia, where almost 5 million individuals are viremic. Elbasvir/grazoprevir is a fixed-dose combination therapy for the treatment of HCV genotype 1 and genotype 4 infection. The present analysis aimed to assess the safety and efficacy of elbasvir/grazoprevir in individuals with HCV infection enrolled at Russian study sites in the C-CORAL study. Patients and Methods: C-CORAL (Protocol PN-5172-067; NCT02251990) was a Phase 3, placebo-controlled, double-blind study conducted throughout Asia and Russia. Treatment-naive participants with chronic HCV infection were randomly assigned to receive immediate or deferred treatment with elbasvir 50 mg/grazoprevir 100 mg once daily for 12 weeks. Participants in the immediate-treatment group received elbasvir/grazoprevir for 12 weeks, and those in the deferred-treatment group received placebo for 12 weeks, followed by open-label elbasvir/grazoprevir for 12 weeks. The primary endpoint was sustained virologic response at 12 weeks after completion of therapy (SVR12). Results: One hundred and nineteen Russian participants were randomized (immediatetreatment group, n=88; deferred-treatment group, n=31). Most participants were white (99%) with HCV genotype 1b infection (97%) and mild-to-moderate (F0–F2) fibrosis (70%). SVR12 was achieved by 98.9% participants in the immediate-treatment group and by 100% of those receiving deferred elbasvir/grazoprevir in the deferred-treatment group. One participant relapsed with nonstructural protein 5A (NS5A) L28M and Y93H resistanceassociated substitutions at baseline and at time of failure. Drug-related adverse events were reported by 19% of participants receiving elbasvir/grazoprevir in the immediate-treatment group and by 16% of those receiving placebo in the deferred-treatment group. No serious adverse event or deaths occurred, and no participant discontinued treatment owing to an adverse event. Conclusion: Elbasvir/grazoprevir for 12 weeks was highly effective in treatment-naive Russian individuals with HCV genotype 1b infection.