Limitations of daclatasvir/asunaprevir plus beclabuvir treatment in cases of NS5A inhibitor treatment failure.

Combined daclatasvir (DCV)/asunaprevir (ASV) plus beclabuvir (BCV) treatment shows a high virological response for genotype 1b chronic hepatitis C patients. However, its efficacy for patients for whom previous direct-acting antiviral (DAA) therapy failed is not known. We analysed the efficacy of DCV/ASV/BCV treatment for HCV-infected mice and chronic hepatitis patients. Human hepatocyte chimaeric mice were injected with serum samples obtained from either a DAA-naïve patient or a DCV/ASV treatment failure and were then treated with DCV/ASV alone or in combination with BCV for 4 weeks. DCV/ASV treatment successfully eliminated the virus in DAA-naïve-patient HCV-infected mice. DCV/ASV treatment failure HCV-infected mice developed viral breakthrough during DCV/ASV treatment, with the emergence of NS5A-L31V/Y93H HCV resistance-associated variants (RAVs) being observed by direct sequencing. DCV/ASV/BCV treatment inhibited viral breakthrough in NS5A-L31V/Y93H-mutated HCV-infected mice, but HCV relapsed with the emergence of NS5B-P495S variants after the cessation of the treatment. The efficacy of the triple therapy was also analysed in HCV-infected patients; one DAA-naïve patient and four prior DAA treatment failures were treated with 12 weeks of DCV/ASV/BCV therapy. Sustained virological response was achieved in a DAA-naïve patient and one of the DCV/ASV treatment failures through DCV/ASV/BCV therapy; however, HCV relapse occurred in the other patients with prior DCV/ASV and/or sofosbuvir/ledipasvir treatment failures. DCV/ASV/BCV therapy seems to have limited efficacy for patients with NS5A RAVs for whom prior DAA treatment has failed.

Short-duration treatment for chronic hepatitis C virus with daclatasvir, asunaprevir, beclabuvir and sofosbuvir (FOURward study).

BACKGROUND & AIMS: The phase 2, FOURward study (NCT02175966) investigated short-duration therapy (4/6 weeks) with four direct-acting antivirals (DAAs) with distinct mechanisms of action in patients infected with hepatitis C virus (HCV) genotype-1. METHODS: Non-cirrhotic patients were randomized 1:1 to DCV-TRIO (fixed-dose daclatasvir 30 mg, asunaprevir 200 mg and beclabuvir 75 mg) twice-daily + sofosbuvir 400 mg once-daily for 4 or 6 weeks. The primary endpoint was sustained virological response at post-treatment Week 12 (SVR12). Patients without SVR12 were offered retreatment based on the DAA resistance profile at failure; patients with resistance to ≤1 DCV-TRIO component received DCV-TRIO + RBV for 12 weeks. RESULTS: Twenty-eight patients with HCV genotype-1 were enrolled; 79% had genotype-1a infection and median baseline HCV-RNA levels were high (9 × 106  IU/mL). Most patients had undetectable HCV-RNA at end of treatment (96% [n=27/28]); however, relapse occurred in 77% (n=10/13) and 43% (n=6/14) treated for 4 and 6 weeks, leading to SVR12 rates of 29% (n=4/14) and 57% (n=8/14) respectively. SVR12 was higher in patients with lower baseline HCV-RNA (<2 million IU/mL, 71% [n=5/7]; ≥2 million IU/mL, 33% [n=7/21]). None of the 16 non-SVR12 patients had NS3 or NS5B resistance-associated substitutions (RAS) detected at failure. All 15 patients retreated with DCV-TRIO + RBV for 12 weeks achieved SVR12. All regimens were well tolerated. CONCLUSIONS: Short-duration treatment with four DAAs with distinct mechanisms of action was insufficient for most patients with genotype-1 infection and high baseline viraemia. Non-SVR12 was not associated with emergence of NS3 or NS5B RAS and retreatment with DCV-TRIO + RBV for 12 weeks led to SVR in all patients.

Interferon-free, direct-acting antiviral therapy for chronic hepatitis C.

The treatment environment for chronic hepatitis C has undergone a revolution, particularly in genotype 1. Gone are interferon-based therapy and its associated tolerability challenges, inadequate response rates and numerous baseline factors that affect response to therapy. New and emerging treatment regimens employ all-oral combinations of direct-acting antiviral agents, and results of clinical trials suggest that these regimens routinely achieve cure rates >90%, even in patients who failed prior interferon-based triple therapy. In 2015, three all-oral FDA-approved regiments will be available for genotype 1 (sofosbuvir /ledipasvir, sofosbuvir/simeprevir, and paritaprevir/r/ombitasvir/dasabuvir). Furthermore, new treatment combinations appear to be more tolerable and require shorter duration of therapy. We provide an overview of the classes of direct-acting antiviral agents (DAAs), the clinical factors affecting their integration into combination therapies and recent findings from trials of such combination therapies in patients with genotype 1 HCV infection.

The Role of CYPs and Transporters in the Biotransformation and Transport of the Anti-hepatitis C Antiviral Agents Asunaprevir, Daclatasvir, and Beclabuvir: Impact of Liver Disease, Race and Drug-drug Interactions on Safety and Efficacy.

Asunaprevir, daclatasvir, and beclabuvir are direct-acting antiviral agents used in the treatment of patients infected with hepatitis C genotype 1b. This article reviews the biotransformation and disposition of these drugs in relation to the safety and efficacy of therapy. CYP3A4 and 3A5 catalyze the oxidative biotransformation of the drugs, while P-glycoprotein mediates their efflux from tissues. Asunaprevir is also a substrate for the influx transporters OATP1B1 and OATP2B1 and the efflux transporter MRP2, while beclabuvir is also a substrate for the efflux transporter BCRP. Liver disease decreases the expression of CYPs and transporters that mediate drug metabolism and disposition. Serum asunaprevir concentrations, but not those of daclatasvir or beclabuvir, are increased in patients with severe liver disease, which may produce toxicity. Pharmacogenomic variation in CYPs and transporters also has the potential to disrupt therapy with asunaprevir, daclatasvir and beclabuvir; some variants are more prevalent in certain racial groups. Pharmacokinetic drug-drug interactions, especially where asunaprevir, daclatasvir, and beclabuvir are victim drugs, are mediated by coadministered rifampicin, ketoconazole and ritonavir, and are attributable to inhibition and/or induction of CYPs and transporters. Conversely, there is also evidence that asunaprevir, daclatasvir and beclabuvir are perpetrators of drug interactions with coadministered rosuvastatin and dextromethorphan. Together, liver disease, pharmacogenomic variation and drug-drug interactions may disrupt therapy with asunaprevir, daclatasvir and beclabuvir due to the impaired function of important CYPs and transporters.

Features of resistance-associated substitutions after failure of multiple direct-acting antiviral regimens for hepatitis C.

BACKGROUND & AIMS: We aimed to clarify the features of resistance-associated substitutions (RASs) after failure of multiple interferon (IFN)-free regimens in HCV genotype 1b infections. METHODS: A total of 1,193 patients with HCV for whom direct-acting antiviral (DAA) treatment had failed were enrolled from 67 institutions in Japan. The RASs in non-structural protein (NS)3, NS5A, and NS5B were determined by population sequencing. RESULTS: Failure of 1, 2, and 3 regimens was observed in 1,101; 80; and 12 patients, respectively. Among patients with failure of 1 regimen, Y56H and D168V in NS3 were more frequently detected after failure of paritaprevir, whereas D168E was more frequently detected after failure of regimens including asunaprevir. R30H and L31-RAS in NS5A were frequently detected after failure of regimens including daclatasvir. The prevalence of Y93-RAS was high irrespective of the regimen. S282T RAS in NS5B was detected in 3.9% of ledipasvir/sofosbuvir failures. The prevalence of D168-RAS increased significantly according to the number of failed regimens (p <0.01), which was similar to that seen with L31-RAS and Y93-RAS. The prevalence of patients with RASs in either NS3 or NS5A, or in both, increased significantly with increasing numbers of failed regimens. The P32del, which is unique to patients for whom DAA had failed, was linked to the absence of Y93H, the presence of L31F, and previous exposure to IFN plus protease inhibitor regimens. CONCLUSIONS: Failure of multiple DAA regimens can lead to the generation of multiple RASs in the NS3 and NS5A regions of the HCV 1b genome. These mutations contribute to viral resistance to multiple treatment regimens and, therefore, should be considered during decision making for treatment of chronic HCV. LAY SUMMARY: Resistance-associated substitutions (RAS) in the genome of the hepatitis C virus are 1 of the major causes for failed treatment. We investigated RASs after failure of various treatments for chronic hepatitis C, and found that more complicated RASs accumulated in the viral genome with successive failed treatments. The highly resistant P32del RAS at NS5A region was uniquely found in patients for whom DAA treatments had failed, and was linked to the presence and absence of specific RASs.

Real-world virological efficacy and safety of daclatasvir/asunaprevir/beclabuvir in patients with chronic hepatitis C virus genotype 1 infection in Japan.

BACKGROUND: The virological efficacy and safety of the direct-acting antiviral (DAA) regimen consisting of daclatasvir, asunaprevir, and beclabuvir (DCV/ASV/BCV) for patients chronically infected with hepatitis C virus (HCV) genotype 1 have not been previously evaluated in Japanese real-world settings. METHODS: In a Japanese nationwide multicenter study, the rate of sustained virologic response (SVR) and safety were analyzed in 91 patients who started the DCV/ASV/BCV regimen between November 2016 and July 2017. SVR rates were compared based on baseline patient characteristics. RESULTS: More than 60% of patients had a history of failure to achieve SVR with interferon (IFN)-free DAA therapy. Overall, 50 of 91 patients (54.9%) achieved SVR. Multivariate analysis identified a history of failure with IFN-free DAA therapy and pretreatment HCV RNA levels as factors significantly associated with treatment failure. Whereas the SVR rate in patients without a history of IFN-free DAA therapy was 91.7% (33 of 36 patients), it was only 30.9% (17 of 55 patients) among patients with a history of IFN-free DAA therapy. The rate of discontinuation due to an adverse event was 4.4%. CONCLUSIONS: Many patients treated with the DCV/ASV/BCV regimen have a history of a failure to achieve SVR with previous IFN-free DAA therapy. SVR rate was not as high as that in pre-approval clinical trial of this regimen in IFN-free DAA-naïve patients. In addition, most patients with a history of failure with IFN-free DAA therapy, particularly the DCV/ASV regimen, showed resistance to this regimen.

Population Pharmacokinetic Analysis of Daclatasvir, Asunaprevir, and Beclabuvir Combination in HCV-Infected Subjects.

A fixed-dose combination of daclatasvir (pangenotypic NS5A inhibitor), asunaprevir (NS3/4A protease inhibitor), and beclabuvir (nonnucleoside NS5B inhibitor) was approved for hepatitis C virus treatment in Japan. The objectives of the analyses were to develop the daclatasvir, asunaprevir, and beclabuvir population pharmacokinetic models for the combination regimen. First, an original population pharmacokinetic model was developed using the data in non-Japanese hepatitis C virus-infected subjects. The model was subsequently updated after a phase 3 study in Japanese hepatitis C virus-infected subjects was available. A total of 11,382, 11,300, and 10,728 pharmacokinetic records from 1,228 subjects were included for daclatasvir, asunaprevir, and beclabuvir in the updated model, respectively. Daclatasvir and beclabuvir pharmacokinetics (PK) were described by a 1-compartment model with linear elimination and asunaprevir PK was described by 2-compartment model with linear elimination. Cirrhosis, baseline, and time-varying ALT were significant covariates on asunaprevir apparent oral clearance. Asian subjects had greater asunaprevir and beclabuvir exposures than white subjects. The effects of all covariates on daclatasvir PK were modest and not considered clinically significant. With the exception of race on asunaprevir and beclabuvir PK, no other parameters for daclatasvir, asunaprevir and beclabuvir population PK models were meaningfully impacted during the refinement with Japanese subjects.

Exposure-Response Analysis for Efficacy of Daclatasvir, Asunaprevir, and Beclabuvir Combinations in HCV-Infected Patients.

The combination regimen of daclatasvir, asunaprevir, and beclabuvir (3DAA regimen) was developed as a fixed-dose combination for the treatment of hepatitis C virus (HCV) infection in Japan. The objectives of this analysis were to characterize the relationship between drug exposure and sustained virologic response at posttreatment week 12 (SVR12) in HCV-infected subjects and to evaluate the impact of demographic covariates and clinical factors on the exposure-response (E-R) relationship. The E-R efficacy analysis was performed with data from phase 2 and phase 3 studies in HCV-infected subjects treated with the 3DAA regimen. The relationship between the probability of achieving SVR12 and exposure to daclatasvir, asunaprevir, and beclabuvir was described using a logistic regression model and included assessments of the potential covariate effects. The impacts of the covariates on the rate of SVR12 and interactions of covariates with the individual drug effects were tested. The final model for SVR12 included effects of non-genotype-1a status, resistance-associated NS5A-Q30 substitution in genotype-1a subjects, and baseline RNA level on the intercept, and effect of prior peg-interferon failure on the beclabuvir slope. Sex, race, age, weight, fibrosis score, alanine transaminase, and cirrhosis status had no statistically significant impact on the rate of SVR12. The individual E-R relationships with each drug, were relatively flat, and the effects of exposure were not significant. With the exception of the NS5A-Q30 substitution in genotype-1a subjects, statistically significant covariate effects had little impact on SVR12 rates. Overall, the E-R model was developed that captured the high SVR12 rates and the effect of covariates for the 3DAA regimen in HCV-infected patients.

Safety Exposure-Response Analysis for Daclatasvir, Asunaprevir, and Beclabuvir Combinations in HCV-Infected Subjects.

The combination regimen of daclatasvir, asunaprevir, and beclabuvir has been developed for the treatment of hepatitis C virus infection. The objectives of this analysis were to characterize the relationship between the exposures of the daclatasvir, asunaprevir, and beclabuvir regimen and liver-related laboratory elevations (Grade 3 or 4 alanine aminotransferase [ALT] and total bilirubin [Tbili]), and to evaluate the impact of selected covariates on the exposure-response relationships. The exposure-response analysis was performed with data from 1 phase 2 and 3 phase 3 studies in hepatitis C virus-infected subjects. The probability of liver-related laboratory elevations were modeled using linear logistic regression. Selected covariates were tested using a forward-addition and backward-elimination approach. The final model for ALT elevation included Asian race, body weight in non-Asian subjects, and asunaprevir exposure. The final model for Tbili elevation included Asian race, fibrosis score (F0-F3 or F4) and asupanprevir exposure. Asian subjects had greater the Grade 3 or 4 ALT and Tbili elevation rates than non-Asians. The Grade 3 or 4 ALT elevation rate increased with decreasing body weight in non-Asian subjects. Subjects with F4 fibrosis score had a higher rate of Grade 3 or 4 Tbili elevation compared to subjects with F0 to F3 fibrosis score. Higher asunaprevir exposure was associated with increases in Grade 3 or 4 ALT and Tbili elevation rates; however, the impact on the ALT elevation was not clinically relevant and the effect on Tbili elevation was smaller than the other significant covariates.

Oxidative degradation pathways of beclabuvir hydrochloride mediated by hydrogen peroxide and UV/Vis light.

Beclabuvir hydrochloride (BCV) is a marketed product for the treatment of hepatitis C viral infection. It contains functional groups such as indole, tertiary amine and amides. Forced degradation studies of BCV revealed different degradation profiles under photo and hydrogen peroxide oxidative conditions. Under the photo-oxidative degradation conditions, the tertiary amine on the piperazine ring was oxidized to form the degradants as the hydroxyl and des-methyl analogs of beclabuvir. However, under the oxidative condition using hydrogen peroxide, the indole ring was oxidized to form a typical kynuric degradant and two unexpected cyclohexyl rearranged diastereomeric degradants. The plausible mechanisms for the photo and hydrogen peroxide mediated oxidative degradation of beclabuvir hydrochloride are proposed.

Potent viral suppression and improvements in alpha-fetoprotein and measures of fibrosis in Japanese patients receiving a daclatasvir/asunaprevir/beclabuvir fixed-dose combination for the treatment of HCV genotype-1 infection.

BACKGROUND: In the UNITY-3 study, 96% sustained virologic response (SVR12) rate was observed in Japanese patients with hepatitis C virus (HCV) genotype (GT)-1 infection treated for 12 weeks with fixed-dose daclatasvir, asunaprevir, and beclabuvir (DCV-TRIO). As HCV clearance may improve liver outcomes, we assessed hepatic fibrosis and alpha-fetoprotein (AFP), a hepatocellular carcinoma risk marker, pre- and post-treatment in UNITY-3. METHODS: Treatment-naive or interferon-experienced UNITY-3 patients with HCV GT-1 who received twice-daily DCV-TRIO were assessed for fibrosis [FibroTest; FibroScan; fibrosis-4 index (FIB-4), aspartate-aminotransferase-to-platelet-ratio index] and AFP at baseline and Weeks 4 (FIB-4 only), 12 or 24 post-treatment. RESULTS: Of 217 patients, 99% had GT-1b infection, 46% were aged > 65 years, 21% had compensated cirrhosis, and 26% baseline HCV-RNA > 107 IU/mL. All GT-1b patients treated ≥ 4 weeks achieved SVR12 with (n = 54) or without (n = 144) baseline NS5A polymorphisms associated with DCV resistance (positions 28/30/31/93). Statistically significant post-treatment reductions from baseline were observed for all fibrosis measures and AFP, with numerically greater reductions in cirrhotic patients. FibroTest category improved in 44%, remained stable in 50%, and worsened in 6% of patients; 98% with baseline AFP < 6 µg/L remained < 6 µg/L and 51% with baseline AFP ≥ 6 µg/L were < 6 µg/L post-treatment. CONCLUSIONS: DCV-TRIO administered for 12 weeks to Japanese patients with primarily GT-1b infection achieved a high SVR12 rate and resulted in improved measures of hepatic fibrosis and serum AFP that may reduce the risk of future liver disease progression and hepatocellular carcinoma, particularly in those with compensated cirrhosis.

Pharmacokinetic and pharmacodynamic evaluation of daclatasvir, asunaprevir plus beclabuvir as a fixed-dose co-formulation for the treatment of hepatitis C.

INTRODUCTION: Many reports have evaluated the clinical efficacy and safety of the fixed-dose all-oral combination of daclatasvir, asunaprevir, and beclabuvir (DCV-TRIO), which was approved in Japan in December 2016 for the treatment of hepatitis C genotype (GT)-1 infection. Areas covered: This article reviews the pharmacodynamic and pharmacokinetic properties of the DCV-TRIO combination. The topics covered include data regarding the drug's absorption, distribution, metabolism, excretion, and antiviral activity strategies. Its therapeutic efficacy and safety in GT-1 infection from phase 2/3 clinical trials are also discussed. Expert opinion: The ideal regimen for the treatment of Hepatitis C virus infection should be potent, pangenotypic, Ribavirin-free, safe, co-formulated, and affordable. Considering these characteristics, DCV-TRIO is neither pangenotypic nor potent enough against GT-1a, regardless of the presence or absence of cirrhosis. Other potential limitations of this regimen are its dosification (twice-daily), and the fact that since it includes a protease inhibitor, it is contraindicated in decompensated cirrhosis. For these reasons, it has only been approved in Japan, where more than 70% of the patients are infected with GT-1b. However, this co-formulation might still have a place in the treatment of non-cirrhotic patients infected with GT-1b provided that massive access to treatment is facilitated.

Daclatasvir, asunaprevir and beclabuvir fixed-dose combination for patients with genotype 1 chronic hepatitis C.

Hepatitis C is killing 350,000 persons per year worldwide, 60% of the cases being patients with genotype 1 (GT-1). The fixed-dose tablet combination of daclatasvir (30 mg)/asunaprevir (200 mg)/beclabuvir (75 mg), DCV-TRIO, is one of the latest drugs in the pipeline of interferon-free direct-acting antiviral hepatitis C virus (HCV) therapies. DCV-TRIO increases the genetic barrier to resistance by acting at the same time against three hepatitis C key viral proteins. Results from the UNITY 1, 2, 3 and 4 phase III clinical trials showed that DCV-TRIO exhibited high sustained virologic responses at 12 weeks (between 92% and 100% for HCV GT-1 treatment-naive patients). Furthermore, DCV-TRIO was well tolerated in all studies with reported adverse events (AEs) with an incidence of at least 10% mostly being headache, diarrhea, fatigue and nausea and few AE-related discontinuations. Further research should focus on more real-life data on DCV-TRIO and on developing a pill regimen that works on other HCV genotypes with high genetic barriers and that is available at a reduced cost.

Asunaprevir for hepatitis C: a safety evaluation.

INTRODUCTION: The introduction of direct-acting antiviral (DAA) agents has revolutionized the treatment of hepatitis C virus (HCV) chronic infection. Non-structural 3 protease inhibitors are currently the most numerous class of DAAs on the market. AREAS COVERED: This review mainly focuses on the tolerability and safety profile of asunaprevir (ASV)-containing DAA regimens. ASV is a second-wave protease inhibitor currently in Phase III clinical development in most countries and already available in Japan. EXPERT OPINION: ASV shows potent antiviral effect and clinical efficacy on HCV genotypes 1 and 4. The all-oral combination daclatasvir/ASV reached high eradication rates in HCV genotype 1b and 4 infection, and a lower efficacy in genotype 1a infection. ASV presents a low potential for drug-drug interaction and a good tolerability as part of multiple, including all-oral, regimens. ASV is associated with a transient and usually mild increase in aminotransferase levels in a low percentage of cases. Due to the impaired pharmacokinetic profile observed in advanced liver disease, ASV use in patients with moderate or severe hepatic impairment is not allowed. In conclusion, ASV represents a powerful weapon against HCV infection and has to be considered an optimal option as a component of genotype tailored interferon-free combinations.

Multiplexed LC-MS/MS method for the simultaneous quantitation of three novel hepatitis C antivirals, daclatasvir, asunaprevir, and beclabuvir in human plasma.

Dual or triple combination regimens of novel hepatitis C direct-acting antivirals (DAA, daclatasvir, asunaprevir, or beclabuvir) provide high sustained virological response rates and reduced frequency of resistance compared to clinical monotherapy. To support pharmacokinetic (PK) assessments in clinical studies, a multiplexed liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitation of daclatasvir, asunaprevir, beclabuvir (BMS-791325) and its active metabolite (BMS-794712) in human plasma was developed and validated. Human plasma samples were extracted with methyl-t-butyl ether followed by an LC-MS/MS analysis, which was conducted in a multiple reaction monitoring (MRM) mode. The lower limits of quantitation (LLOQ) were 1 ng/mL for daclatasvir, asunaprevir, and BMS-794712, and 2 ng/mL for beclabuvir. Intra-run precision (≤4.5% CV), inter-run precision (≤2.9% CV), and accuracy (±5.3% deviation) based on different concentration levels (low, geometric mean, mid and high) of the quality control samples (QCs) provided evidence of the methods accuracy and precision. Selectivity and matrix effect on LC-MS/MS detection, stability in plasma, and potential interference of coadministered drugs (ribavirin and interferon) were all evaluated and the results were acceptable. Method reproducibility was demonstrated by the reanalysis of a portion of study samples. The cross-validation results for QCs demonstrated the equivalency between this method and two single-analyte methods which were previously validated for quantitation of daclatasvir in human plasma. This approach of using a multiplexed LC-MS/MS method for the simultaneous quantitation of three DAAs is time- and cost-effective, and can maintain good data quality in sample analysis.