Organic Anion Transporting Polypeptide Inhibition Dramatically Increases Plasma Exposure but not Pharmacodynamic Effect nor Inferred Hepatic Intracellular Exposure of Firsocostat.

Firsocostat (FIR: previously GS-0976), a highly sensitive OATP substrate, reduces hepatic de novo lipogenesis (DNL) by inhibiting acetyl-CoA carboxylases (ACC). Measuring the pharmacodynamic (PD) efficacy of FIR on DNL provides a unique opportunity to determine optimal dosing strategies for liver-targeted OATP substrates in settings of altered OATP function. A randomized, four-way crossover drug-drug interaction study was conducted. Hepatic DNL, a marker for ACC activity, was measured in 28 healthy volunteers after reference, single dose FIR 10 mg, FIR 10 mg plus the OATP inhibitor rifampin (RIF) 300 mg i.v., or RIF 300 mg i.v. (control for DNL effect of RIF), each separated by a 7-day washout. Samples were collected for pharmacokinetic (PK) and PD assessments through 24 hours after each treatment. Hepatic DNL and its inhibition by FIR were assessed. Twenty-four subjects completed the study. All adverse events were mild. RIF alone increased hepatic DNL area under the effect curve from time of administration up to the time of the last quantifiable concentration (AUEClast ; 35.7%). Despite a 5.2-fold increase in FIR plasma exposure (area under the concentration-time curve from zero to infinity (AUCinf )) when administered with RIF, FIR alone, and FIR + RIF had the same hepatic PD effect, 37.1% and 34.9% reduction in DNL AUEClast , respectively, compared with their respective controls. These findings indicate that large decreases in OATP activity do not alter hepatic intracellular exposure (as inferred by no change in PD) for drugs that are primarily eliminated hepatically and permeability rate-limited, such as FIR. These results support PK theory that has been difficult to test and provide practical guidance on administration of liver-targeted drugs in settings of reduced OATP function.

Safety and Efficacy of Ledipasvir-Sofosbuvir With or Without Ribavirin for Chronic Hepatitis C in Children Ages 6-11.

Currently, there are no interferon-free treatments available for hepatitis C virus (HCV)-infected patients younger than 12 years. We evaluated the safety and effectiveness of the all-oral regimen ledipasvir-sofosbuvir ± ribavirin in HCV-infected children aged 6 to <12 years. In an open-label study, patients aged 6 to <12 years received ledipasvir 45 mg-sofosbuvir 200 mg as two fixed-dose combination tablets 22.5/100 mg once daily, with or without ribavirin, for 12 or 24 weeks, depending on HCV genotype and cirrhosis status. The primary efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Twelve patients underwent intensive pharmacokinetic sampling to confirm the appropriateness of the ledipasvir and sofosbuvir dosages. Ninety-two patients were enrolled (88 genotype 1, 2 genotype 3, and 2 genotype 4), with a median age of 9 years (range, 6-11). Most were perinatally infected (97%) and treatment-naive (78%). Two were confirmed to have cirrhosis, while the degree of fibrosis was unknown in 55 patients. The overall SVR12 rate was 99% (91/92; 95% confidence interval, 94%-100%). The single patient not reaching SVR relapsed 4 weeks after completing 12 weeks of treatment. The most common adverse events were headache and pyrexia. One patient had three serious adverse events, which were considered to be not related to study treatment: tooth abscess, abdominal pain, and gastroenteritis. The area under the concentration-time curve and maximum concentration values for sofosbuvir, its primary metabolite GS-331007, and ledipasvir were within predefined pharmacokinetic equivalence boundaries (50%-200%) compared to values in adults in phase 2/3 of the ledipasvir and sofosbuvir studies. Conclusion: Ledipasvir-sofosbuvir was well tolerated and highly effective in children 6 to <12 years old with chronic HCV.

The Drug-Drug Interaction Potential of Antiviral Agents for the Treatment of Chronic Hepatitis C Infection.

Several safe and highly effective direct-acting antiviral (DAA) drugs for chronic hepatitis C virus (HCV) have been developed and greatly increase the number of therapeutic options available to successfully treat HCV infection. However, because treatment regimens contain at least two drugs (e.g., elbasvir and grazoprevir, glecaprevir and pibrentasvir, or sofosbuvir with daclatasvir, simeprevir, ledipasvir, or velpatasvir) and up to five drugs (ombitasvir/paritaprevir/ritonavir plus dasabuvir with or without ribavirin), the potential for drug-drug interactions (DDIs) becomes an important consideration for HCV-infected individuals with comorbidities that require concomitant medications, such as human immunodeficiency virus/HCV coinfection or immunosuppression after liver transplantation. This review details the pharmacokinetics and DDI potential of approved DAAs for the treatment of HCV infection.

A phase IIIb study of ledipasvir/sofosbuvir fixed-dose combination tablet in treatment-naïve and treatment-experienced Korean patients chronically infected with genotype 1 hepatitis C virus.

BACKGROUND: The standard-of-care regimen for chronic hepatitis C virus (HCV) infection in Korea, pegylated-interferon-alpha plus ribavirin, is poorly tolerated. Ledipasvir/sofosbuvir is a two-drug, fixed-dose combination tablet approved in the USA, European Union, and Japan for chronic genotype 1 HCV infection. METHODS: This single-arm, phase IIIb study (NCT02021656) investigated the efficacy and safety of ledipasvir/sofosbuvir fixed-dose combination tablet for 12 weeks in treatment-naïve and treatment-experienced Korean patients chronically infected with genotype 1 HCV with or without compensated cirrhosis. RESULTS: The proportion of patients with sustained virologic response 12 weeks after treatment discontinuation (SVR12) was 99 % (92/93), with rates of 100 % (46/46) and 98 % (46/47) in treatment-naïve and treatment-experienced patients, respectively. There were no on-treatment failures. One patient relapsed after the end of treatment. The most common treatment-emergent adverse events were headache (8 %, 7/93) and fatigue (6 %, 6/93). There were no grade 3 or 4 adverse events, seven grade 3 laboratory abnormalities, and one premature discontinuation of study treatment (due to nonserious mouth ulceration). None of the three reported serious adverse events were related to treatment. CONCLUSIONS: These data suggest that 12 weeks of ledipasvir/sofosbuvir is effective and well tolerated in treatment-naïve and treatment-experienced Korean patients with chronic genotype 1 HCV infection.

Ledipasvir/sofosbuvir fixed-dose combination tablet in Taiwanese patients with chronic genotype 1 hepatitis C virus.

BACKGROUND AND AIM: Pegylated-interferon-alpha plus ribavirin is the current standard-of-care regimen for treating chronic hepatitis C virus (HCV) infection in Taiwan; however, interferon-based regimens can be poorly tolerated. The interferon-free, two-drug, fixed-dose combination tablet ledipasvir/sofosbuvir is approved in Europe, the USA, and Japan for treating chronic genotype 1 HCV infection. Little is known about its efficacy/safety in Taiwanese patients. METHODS: In this multicenter, open-label, phase 3b (NCT02021656) study, 85 Taiwanese patients (n = 42, treatment-naïve; n = 43, treatment-experienced) with chronic genotype 1 HCV infection (±compensated cirrhosis) received 12 weeks of ledipasvir/sofosbuvir fixed-dose combination tablet. The primary efficacy end point was the proportion of patients with sustained virologic response 12 weeks after treatment discontinuation (SVR12). Safety and pharmacokinetic data were collected. RESULTS: The overall SVR12 rate was 98% (83/85), with 100% (42/42) and 95% (41/43) of treatment-naïve and treatment-experienced patients, respectively, achieving SVR12. There were no on-treatment virologic failures. One patient relapsed after treatment discontinuation; one patient withdrew consent on day 2. The most common treatment-emergent adverse event (AE) was headache (14%, 12/85). There was one grade 3 AE (small cell lung cancer unrelated to ledipasvir/sofosbuvir), no grade 4 AEs, and four grade 3-4 laboratory abnormalities. Only the patient with small cell lung cancer prematurely discontinued treatment. Two patients reported three serious AEs; none was considered related to ledipasvir/sofosbuvir. CONCLUSIONS: Data from this phase 3b study suggest that 12 weeks of once-daily treatment with the interferon-free, ribavirin-free regimen ledipasvir/sofosbuvir is effective and well-tolerated in Taiwanese patients with chronic genotype 1 HCV infection, irrespective of treatment history.

Few Drugs Display Flip-Flop Pharmacokinetics and These Are Primarily Associated with Classes 3 and 4 of the BDDCS.

This study was conducted to determine the number of drugs exhibiting flip-flop pharmacokinetics following oral (p.o.) dosing from immediate-release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. The literature was searched for drugs displaying flip-flop kinetics (i.e., absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (nine drugs), monkey (three drugs), horse (two drugs), and/or rabbit (two drugs). Nineteen of the 22 drugs exhibiting flip-flop kinetics were BDDCS Classes 3 and 4. One of the three exceptions, meclofenamic acid (Class 2), was identified in the horse; however, it would not exhibit flip-flop kinetics in humans where the p.o. dosing terminal half-life is 1.4 h. The second, carvedilol, can be explained based on solubility issues, but the third sapropterin dihydrochloride (nominally Class 1) requires further consideration. The few drugs displaying p.o. flip-flop kinetics in humans are predominantly BDDCS Classes 3 and 4. New molecular entities predicted to be BDDCS Classes 3 and 4 could be liable to exhibit flip-flop kinetics when the elimination half life is short and should be suspected to be substrates for intestinal transporters.

The oral toll-like receptor-7 agonist GS-9620 in patients with chronic hepatitis B virus infection.

BACKGROUND & AIMS: GS-9620 is an oral agonist of toll-like receptor 7, a pattern-recognition receptor whose activation results in innate and adaptive immune stimulation. We evaluated the safety, pharmacokinetics, and pharmacodynamics of GS-9620 in patients with chronic hepatitis B. METHODS: In two double-blind, phase 1b trials of identical design, 49 treatment-naïve and 51 virologically suppressed patients were randomized 5:1 to receive GS-9620 (at doses of 0.3mg, 1mg, 2mg, 4mg) or placebo as a single dose or as two doses seven days apart. Pharmacodynamic assessment included evaluation of peripheral mRNA expression of interferon-stimulated gene 15 (ISG15), serum interferon gamma-induced protein 10 and serum interferon (IFN)-alpha. RESULTS: Overall, 74% of patients were male and 75% were HBeAg negative at baseline. No subject discontinued treatment due to adverse events. Fifty-eight percent experienced ⩾1 adverse event, all of which were mild to moderate in severity. The most common adverse event was headache. No clinically significant changes in HBsAg or HBV DNA levels were observed. Overall, a transient dose-dependent induction of peripheral ISG15 gene expression was observed peaking within 48 hours of dosing followed by return to baseline levels within seven days. Higher GS-9620 dose, HBeAg positive status, and low HBsAg level at baseline were independently associated with greater probability of ISG15 response. Most patients (88%) did not show detectable levels of serum IFN-alpha at any time point. CONCLUSIONS: Oral GS-9620 was safe, well tolerated, and associated with induction of peripheral ISG15 production in the absence of significant systemic IFN-alpha levels or related symptoms.

Sofosbuvir plus ribavirin in Japanese patients with chronic genotype 2 HCV infection: an open-label, phase 3 trial.

Genotype 2 hepatitis C virus (HCV) accounts for up to 30% of chronic HCV infections in Japan. The standard of care for patients with genotype 2 HCV - peginterferon and ribavirin for 24 weeks - is poorly tolerated, especially among older patients and those with advanced liver disease. We conducted a phase 3, open-label study to assess the efficacy and safety of an all-oral combination of the NS5B polymerase inhibitor sofosbuvir and ribavirin in patients with chronic genotype 2 HCV infection in Japan. We enrolled 90 treatment-naïve and 63 previously treated patients at 20 sites in Japan. All patients received sofosbuvir 400 mg plus ribavirin (weight-based dosing) for 12 weeks. The primary endpoint was sustained virologic response at 12 weeks after therapy (SVR12). Of the 153 patients enrolled and treated, 60% had HCV genotype 2a, 11% had cirrhosis, and 22% were over the aged 65 or older. Overall, 148 patients (97%) achieved SVR12. Of the 90 treatment-naïve patients, 88 (98%) achieved SVR12, and of the 63 previously treated patients, 60 (95%) achieved SVR12. The rate of SVR12 was 94% in patients with cirrhosis and in those aged 65 and older. No patients discontinued study treatment due to adverse events. The most common adverse events were nasopharyngitis, anaemia and headache. Twelve weeks of sofosbuvir and ribavirin resulted in high rates of SVR12 in treatment-naïve and previously treated patients with chronic genotype 2 HCV infection. The treatment was safe and well tolerated by patients, including the elderly and those with cirrhosis.