Safety and efficacy of glecaprevir/pibrentasvir in patients with chronic hepatitis C genotypes 1-6 receiving opioid substitution therapy.

BACKGROUND: International guidelines recommend treatment of hepatitis C virus (HCV) infection in people who inject drugs (PWID), including those on opioid substitution therapy (OST). The pangenotypic combination of glecaprevir and pibrentasvir has shown high sustained virologic response at post-treatment Week 12 (SVR12) in clinical trials. Herein, we evaluate the safety and efficacy of glecaprevir/pibrentasvir in patients receiving OST. METHODS: Pooled data from patients with HCV genotypes 1-6 who were treated with glecaprevir/pibrentasvir for 8, 12, or 16 weeks in eight Phase 2 and 3 trials were categorized by use of OST. Treatment completion, treatment adherence, SVR12, adverse events (AEs), and laboratory abnormalities were evaluated for patients receiving and not receiving OST. RESULTS: Among 2256 patients, 157 (7%) were receiving OST. Compared with patients not receiving OST, OST patients were younger (mean age, 46.8 vs 52.8 years), male (69% vs 54%), white (93% vs 80%), HCV treatment-naïve (86% vs 72%), had HCV genotype 3 (60% vs 26%), and had a history of depression or bipolar disorder (43% vs 19%). Most patients completed (OST: 98% [n/N = 154/157]; non-OST: 99% [n/N = 2070/2099]) and were adherent (received ≥90% of study drug doses) to glecaprevir/pibrentasvir treatment (OST: 98% [n/N = 121/123]; non-OST: 99% [n/N = 1884/1905] among patients with available data). In the intention-to-treat population, SVR12 rates in OST and non-OST patients were 96.2% (n/N = 151/157; 95% CI 93.2-99.2) and 97.9% (n/N = 2055/2099; 95% CI 97.3-98.5), respectively. For OST patients, reasons for nonresponse included virologic relapse (<1%; n = 1), premature study drug discontinuation (<1%; n = 1), and loss to follow-up (3%; n = 4). AEs occurring in ≥10% of OST patients were headache, fatigue, and nausea. Drug-related serious AEs, AEs leading to study drug discontinuation, and Grade 3 or higher laboratory abnormalities were infrequent in both groups (<1%). No HCV reinfections occurred through post-treatment Week 12. CONCLUSION: Glecaprevir/pibrentasvir is highly efficacious and well tolerated in HCV-infected patients receiving OST.

Dynamic changes in innate immune responses during direct-acting antiviral therapy for HCV infection.

The role of the endogenous interferon (IFN) system has been well characterized during IFN-based therapy for chronic hepatitis C virus (HCV) infection; less is known for direct-acting antivirals (DAAs). In this phase 3b open-label study, we assessed changes in IFN-stimulated genes (ISGs) in non-cirrhotic treatment-naïve or pegIFN/RBV-experienced HCV-GT1a-infected patients receiving paritaprevir/ritonavir/ombitasvir + dasabuvir + ribavirin (PrOD + R) for 12 weeks. ISG expression was quantified from peripheral blood mononuclear cells at baseline, treatment weeks (TW)2, TW4, TW8, end of treatment (EOT) and at post-treatment week 12. Paired sera were used to assess IFN-α/IFN-related chemokines/cytokines. Twenty-five patients were enrolled. Overall sustained virologic response (SVR)12 was 92% (no virologic failure [VF]) and 100% for those completing the study protocol. Two patients were excluded from the ISG analysis due to lack of post-treatment samples. The majority of ISGs were downregulated at TW2-TW4 (nadir TW4); however, a relative increase was observed at TW8-EOT, although levels were lower than baseline. This downregulation was accompanied by increases in IFN-α/IFN-related chemokines, a finding not observed with TH 1/2-related cytokines. Following SVR, ISG expression returned to TW2 levels. In conclusion, PrOD + R for 12 weeks was well-tolerated with no VF. Our data demonstrate dynamic alterations in innate immune profiles during highly potent IFN-free DAA therapy. The downregulation of ISG post-therapy suggests reversal of the "exhausted" ISG phenotype following SVR, and the rise in ISGs and IFN-α/IFN-responsive chemokines late during therapy suggests resetting of IFN responsiveness that may be relevant in determining duration of or immunological sequelae from DAA therapy, including HBV reactivation.

Reduced ITPase activity and favorable IL28B genetic variant protect against ribavirin-induced anemia in interferon-free regimens.

BACKGROUND: Genetic variants of inosine triphosphatase (ITPA) that confer reduced ITPase activity are associated with protection against ribavirin(RBV)-induced hemolytic anemia in peginterferon(IFN)/RBV-based treatment of hepatitis C virus (HCV). Patients with reduced ITPase activity showed improved treatment efficacy when treated with IFN/RBV. In addition, a genetic polymorphism near the IL28B gene is associated with an improved response to IFN/RBV treatment. RBV has been an important component of IFN-containing regimens, and is currently recommended in combination with several IFN-free regimens for treatment of harder to cure HCV infections. AIM: To evaluate whether genetic variations that reduce ITPase activity impact RBV-induced anemia in IFN-free/RBV regimens. METHODS: In this study, genetic analyses were conducted in the PEARL-IV trial to investigate the effect of activity-reducing ITPA variants as well as IL28B polymorphism on anemia, platelet (PLT) counts, and virologic response in HCV genotype1a-infected patients treated with the direct-acting antiviral (DAA) regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir±RBV. RESULTS: Reduction in ITPase activity and homozygosity for the IL28Brs12979860 CC genotype protected against RBV-induced anemia. In patients receiving RBV, reduced ITPase activity was associated with reduced plasma RBV concentration and higher PLT counts. ITPase activity had no impact on response to DAA treatment, viral kinetics, or baseline IP-10 levels. CONCLUSIONS: Our study demonstrates that genetics of ITPA and IL28B may help identify patients protected from RBV-induced anemia when treated with IFN-free regimens. Our work demonstrates for the first time that IL28B genetics may also have an impact on RBV-induced anemia. This may be of particular significance in patients with difficult-to-cure HCV infections, such as patients with decompensated cirrhosis where RBV-containing regimens likely will continue to be recommended.

Glecaprevir/Pibrentasvir Treatment in Liver or Kidney Transplant Patients With Hepatitis C Virus Infection.

Well-tolerated, ribavirin-free, pangenotypic hepatitis C virus (HCV) treatments for transplant recipients remain a high priority. Once-daily glecaprevir/pibrentasvir demonstrates high rates of sustained virologic response at 12 weeks posttreatment (SVR12) across all major HCV genotypes (GTs). This trial evaluated the safety and efficacy of glecaprevir/pibrentasvir for patients with chronic HCV GT1-6 infection who had received a liver or kidney transplant. MAGELLAN-2 was a phase 3, open-label trial conducted in patients who were ≥3 months posttransplant. Patients without cirrhosis who were HCV treatment-naive (GT1-6) or treatment-experienced (GT1, 2, 4-6; with interferon-based therapy with or without sofosbuvir, or sofosbuvir plus ribavirin) received glecaprevir/pibrentasvir (300/120 mg) once daily for 12 weeks. The primary endpoint compared the percentage of patients receiving glecaprevir/pibrentasvir with SVR12 to a historic SVR12 rate based on the standard of care. Safety of glecaprevir/pibrentasvir was assessed. In total, 80 liver transplant and 20 kidney transplant patients participated in the trial. Most patients had no or minimal fibrosis (80% had fibrosis scores F0-F1) and were infected with HCV GT1 (57%) or GT3 (24%). The overall SVR12 was 98% (n/N = 98/100; 95% confidence interval, 95.3%-100%), which exceeded the prespecified historic standard-of-care SVR12 threshold of 94%. One patient experienced virologic failure. One patient discontinued because of an adverse event considered to be unrelated to treatment; this patient achieved SVR12. Adverse events were mostly mild in severity, and laboratory abnormalities were infrequent. CONCLUSION: Once-daily glecaprevir/pibrentasvir for 12 weeks is a well-tolerated and efficacious, ribavirin-free treatment for patients with chronic HCV GT1-6 infection who have received a liver or kidney transplant. (ClinicalTrials.gov NCT02692703.) (Hepatology 2018; 00:000-000).

Synthesis and Biological Characterization of Aryl Uracil Inhibitors of Hepatitis C Virus NS5B Polymerase: Discovery of ABT-072, a trans-Stilbene Analog with Good Oral Bioavailability.

ABT-072 is a non-nucleoside HCV NS5B polymerase inhibitor that was discovered as part of a program to identify new direct-acting antivirals (DAAs) for the treatment of HCV infection. This compound was identified during a medicinal chemistry effort to improve on an original lead, inhibitor 1, which we described in a previous publication. Replacement of the amide linkage in 1 with a trans-olefin resulted in improved compound permeability and solubility and provided much better pharmacokinetic properties in preclinical species. Replacement of the dihydrouracil in 1 with an N-linked uracil provided better potency in the genotype 1 replicon assay. Results from phase 1 clinical studies supported once-daily oral dosing with ABT-072 in HCV infected patients. A phase 2 clinical study that combined ABT-072 with the HCV protease inhibitor ABT-450 provided a sustained virologic response at 24 weeks after dosing (SVR24) in 10 of 11 patients who received treatment.

Hepatic Pharmacokinetics and Pharmacodynamics With Ombitasvir/Paritaprevir/Ritonavir Plus Dasabuvir Treatment and Variable Ribavirin Dosage.

Background: It is unknown whether ribavirin (RBV) coadministration modifies the early rate of decline of hepatitis C virus (HCV) RNA in the liver versus plasma compartments, specifically. Methods: This partially randomized, open-label, phase 2 study enrolled treatment-naive, noncirrhotic patients with HCV genotype 1a. Patients were randomized 1:1 into Arms A and B, and then enrolled in Arm C. Patients received ombitasvir/paritaprevir/ritonavir plus dasabuvir for 12 weeks with either: no RBV for the first 2 weeks followed by weight-based dosing thereafter (Arm A), weight-based RBV for all 12 weeks (Arm B), or low-dose RBV (600 mg) once daily for all 12 weeks. Fine needle aspiration (FNA) was used to determine HCV RNA decline within liver. Results: Baseline HCV RNA was higher and declined more rapidly in plasma than liver; however, RBV dosing did not impact either median plasma or liver HCV RNA decline during the first 2 weeks of treatment. Liver-to-plasma drug concentrations were variable over time. The most common adverse event was pain associated with FNA. Conclusions: Coadministration of RBV had minimal visible impact on the plasma or liver kinetics of HCV RNA decline during the first 2 weeks of treatment, regardless of RBV dosing.

Ombitasvir, paritaprevir, and ritonavir plus dasabuvir for 8 weeks in previously untreated patients with hepatitis C virus genotype 1b infection without cirrhosis (GARNET): a single-arm, open-label, phase 3b trial.

BACKGROUND: Clinical studies have shown high rates of sustained virological response (hepatitis C virus [HCV] RNA <15 IU/mL) at post-treatment week 12 (SVR12) in patients with genotype 1b infection with and without cirrhosis who received coformulated ombitasvir, paritaprevir, and ritonavir, plus dasabuvir, without ribavirin, for 12 weeks. In this study, we aimed to assess 8-week treatment with ombitasvir, paritaprevir, and ritonavir, plus dasabuvir, without ribavirin in patients infected with HCV genotype 1b without cirrhosis. METHODS: We did a multicentre, open-label, single-arm, phase 3b study (GARNET) in 20 hospitals or clinics in Australia, Canada, France, Germany, Israel, Italy, Spain, and the UK, to assess the safety and efficacy of an 8-week treatment duration of once-daily oral ombitasvir 25 mg, paritaprevir 150 mg, and ritonavir 100 mg, plus twice-daily oral dasabuvir 250 mg in previously untreated patients with chronic HCV genotype 1b infection without cirrhosis (as assessed by liver biopsy, transient elastography, or serum markers). Eligible patients were aged at least 18 years, with more than 1000 IU/mL HCV RNA, and a laboratory result at screening indicating infection with HCV genotype 1b subtype only. Patients were excluded if they had evidence of HCV genotype or subtype other than genotype 1b, if they tested positive for hepatitis B surface antigen or anti-HIV antibody at screening, or if they had previously been treated for HCV. The primary endpoint was the proportion of patients with SVR12; the primary endpoint and safety were assessed in all patients who received at least one dose of study drugs. This trial is registered with ClinicalTrials.gov, number NCT02582632. FINDINGS: Patients were screened between Nov 24, 2015, and March 1, 2016, and 166 patients were enrolled. 163 (98%) of 166 enrolled patients had HCV genotype 1b infection, and three (2%) of 166 had other genotypes or subtypes (genotype 1a, genotype 1d, and genotype 6). All enrolled patients received at least one dose of study drugs. 162 (98% [95% CI 95·3-99·9]) of 166 patients achieved SVR12. One patient discontinued treatment on day 45 due to adverse events. Most adverse events were mild in severity, and the most common adverse events were headache (35 [21%] of 166) and fatigue (28 [17%] of 166). Two (1%) of 166 patients had serious adverse events; neither were considered related to study drug treatment. INTERPRETATION: Treatment with ombitasvir, paritaprevir, and ritonavir, plus dasabuvir, without ribavirin, for 8 weeks was efficacious and well tolerated. 8-week treatment options for previously untreated patients with HCV genotype 1b infection without cirrhosis are limited; shortening the treatment duration might reduce the burden associated with medical visits and procedures, thereby improving access to care and enabling the treatment of more patients. FUNDING: AbbVie.

Paritaprevir and Ritonavir Liver Concentrations in Rats as Assessed by Different Liver Sampling Techniques.

The liver is crucial to pharmacology, yet substantial knowledge gaps exist in the understanding of its basic pharmacologic processes. An improved understanding for humans requires reliable and reproducible liver sampling methods. We compared liver concentrations of paritaprevir and ritonavir in rats by using samples collected by fine-needle aspiration (FNA), core needle biopsy (CNB), and surgical resection. Thirteen Sprague-Dawley rats were evaluated, nine of which received paritaprevir/ritonavir at 30/20 mg/kg of body weight by oral gavage daily for 4 or 5 days. Drug concentrations were measured using liquid chromatography-tandem mass spectrometry on samples collected via FNA (21G needle) with 1, 3, or 5 passes (FNA1, FNA3, and FNA5); via CNB (16G needle); and via surgical resection. Drug concentrations in plasma were also assessed. Analyses included noncompartmental pharmacokinetic analysis and use of Bland-Altman techniques. All liver tissue samples had higher paritaprevir and ritonavir concentrations than those in plasma. Resected samples, considered the benchmark measure, resulted in estimations of the highest values for the pharmacokinetic parameters of exposure (maximum concentration of drug in serum [Cmax] and area under the concentration-time curve from 0 to 24 h [AUC0-24]) for paritaprevir and ritonavir. Bland-Altman analyses showed that the best agreement occurred between tissue resection and CNB, with 15% bias, followed by FNA3 and FNA5, with 18% bias, and FNA1 and FNA3, with a 22% bias for paritaprevir. Paritaprevir and ritonavir are highly concentrated in rat liver. Further research is needed to validate FNA sampling for humans, with the possible derivation and application of correction factors for drug concentration measurements.

Drug-Drug Interactions Between the Anti-Hepatitis C Virus 3D Regimen of Ombitasvir, Paritaprevir/Ritonavir, and Dasabuvir and Eight Commonly Used Medications in Healthy Volunteers.

BACKGROUND AND AIMS: The three direct-acting antiviral regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir (3D regimen) is approved for treatment of hepatitis C virus (HCV) genotype 1 infection. Drug-drug interaction (DDI) studies of the 3D regimen and commonly used medications were conducted in healthy volunteers to provide information on coadministering these medications with or without dose adjustments. METHODS: Three phase I studies evaluated DDIs between the 3D regimen (ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily + dasabuvir 250 mg twice daily) and hydrocodone bitartrate/acetaminophen (5/300 mg), metformin hydrochloride (500 mg), diazepam (2 mg), cyclobenzaprine hydrochloride (5 mg), carisoprodol (250 mg), or sulfamethoxazole/trimethoprim (SMZ/TMP) (800/160 mg twice daily), all administered orally. DDI magnitude was determined using geometric mean ratios and 90 % confidence intervals for the maximum plasma concentration (C max) and area under the plasma concentration-time curve (AUC). RESULTS: Changes in exposures (C max and AUC geometric mean ratios) of acetaminophen, metformin, sulfamethoxazole, trimethoprim, and diazepam were ≤25 % upon coadministration with the 3D regimen. The C max and AUC of nordiazepam, an active metabolite of diazepam, increased by 10 % and decreased by 44 %, respectively. Exposures of cyclobenzaprine and carisoprodol decreased by ≤40 and ≤46 %, respectively, whereas exposures of hydrocodone increased up to 90 %. Ombitasvir, paritaprevir, ritonavir, and dasabuvir exposures changed by ≤25 %, except for a 37 % decrease in paritaprevir C max with metformin and a 33 % increase in dasabuvir AUC with SMZ/TMP. CONCLUSIONS: Acetaminophen, metformin, sulfamethoxazole, and trimethoprim can be coadministered with the 3D regimen without dose adjustment. Higher doses may be needed for diazepam, cyclobenzaprine, and carisoprodol based on clinical monitoring. A 50 % lower dose and/or clinical monitoring should be considered for hydrocodone. No dose adjustment is necessary for the 3D regimen.

A food effect study and dose proportionality study to assess the pharmacokinetics and safety of bardoxolone methyl in healthy volunteers.

This study investigated the effect of food on the plasma pharmacokinetics of bardoxolone methyl, an antioxidant inflammation modulator, at a 20 mg dose, and the dose proportionality of bardoxolone methyl pharmacokinetics from 20 to 80 mg. It was a single-dose study conducted at a single center in 32 healthy volunteers aged 18-45 years using an amorphous spray-dried dispersion formulation of bardoxolone methyl. In Part A, 16 subjects received single 20 mg doses of bardoxolone methyl under fasting and non-fasting conditions. In Part B, 16 subjects received a single 60 or 80 mg dose of bardoxolone methyl and a matching placebo dose under fasting conditions. Blood samples for pharmacokinetic analysis were taken over 120 hours following dose administration. Single dose administration of 20, 60, and 80 mg bardoxolone methyl was safe and well-tolerated in healthy volunteers. Total bardoxolone methyl exposure was unchanged in the presence of food. However, doses of bardoxolone methyl above 20 mg appear to have a saturated dissolution or absorption process and are associated with less than proportional increases in drug exposure.

Opioid tolerance development: a pharmacokinetic/pharmacodynamic perspective.

The opioids are commonly used to treat acute and severe pain. Long-term opioid administration eventually reaches a dose ceiling that is attributable to the rapid onset of analgesic tolerance coupled with the slow development of tolerance to the untoward side effects of respiratory depression, nausea and decreased gastrointestinal motility. The need for effective-long term analgesia remains. In order to develop new therapeutics and novel strategies for use of current analgesics, the processes that mediate tolerance must be understood. This review highlights potential pharmacokinetic (changes in metabolite production, metabolizing enzyme expression, and transporter function) and pharmacodynamic (receptor type, location and functionality; alterations in signaling pathways and cross-tolerance) aspects of opioid tolerance development, and presents several pharmacodynamic modeling strategies that have been used to characterize time-dependent attenuation of opioid analgesia.