Safety and Pharmacokinetics of Glecaprevir/Pibrentasvir in Adults With Chronic Genotype 1-6 Hepatitis C Virus Infections and Compensated Liver Disease

Background

Untreated, chronic hepatitis C virus (HCV) infection may lead to progressive liver damage, which can be mitigated by successful treatment. This integrated analysis reports the safety, efficacy, and pharmacokinetics (PK) of the ribavirin-free, direct-acting, antiviral, fixed-dose combination of glecaprevir/pibrentasvir (G/P) in patients with chronic HCV genotype 1–6 infections and compensated liver disease, including patients with chronic kidney disease stages 4 or 5 (CKD 4/5).

Methods

Data from 9 Phase II and III clinical trials, assessing the efficacy and safety of G/P treatment for 8–16 weeks, were included. The presence of cirrhosis was determined at screening using a liver biopsy, transient elastography, or serum biomarkers. The objectives were to evaluate safety, the rate of sustained virologic response at post-treatment week 12 (SVR₁₂), and steady-state PK by cirrhosis status.

Results

Among 2369 patients, 308 (13%) were Child-Pugh Class A, including 20 with CKD 4/5. Overall, <1% of patients experienced an adverse event (AE) that led to G/P discontinuation or G/P-related serious AEs (SAEs). The most common AEs were headache and fatigue, occurring at similar frequencies with and without cirrhosis. SAEs were more common in patients with CKD 4/5, but all were unrelated to G/P. There were no cases of drug-induced liver injury or clinically relevant hepatic decompensation. SVR₁₂ rates were 96.4% (297/308) with compensated cirrhosis and 97.5% (2010/2061) without cirrhosis. PK analysis demonstrated a 2.2-fold increase in glecaprevir exposure, but not pibrentasvir exposure, in patients with compensated cirrhosis.

Conclusions

G/P was safe and efficacious in patients with compensated liver disease, including those with CKD 4/5.

Clinical Trials Registration

NCT02243280, NCT02243293, NCT02604017, NCT02640482, NCT02640157, NCT02636595, NCT02642432, NCT02651194, and NCT02446717

Ombitasvir/paritaprevir/ritonavir and dasabuvir with or without sofosbuvir for patients with hepatitis C virus genotype 1 infection who failed a prior course of direct-acting antiviral therapy

INTRODUCTION

Despite high efficacy of current direct-acting antiviral agents (DAAs) in treating chronic hepatitis C virus (HCV) infection, a small portion of patients fail treatment. QUARTZ-I was a phase 2, open-label, multicenter, two-part study that assessed the safety and efficacy of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r) with dasabuvir (DSV) with or without the addition of sofosbuvir (SOF) and/or ribavirin (RBV) in DAA treatment-experienced adults with chronic HCV GT1 infection.

MATERIALS AND METHODS

Genotype 1 HCV-infected patients with or without compensated cirrhosis had prior treatment failure to any DAA (part 1) or ledipasvir/SOF (part 2). Patients received OBV/PTV/r + DSV ± SOF with or without RBV for 12 or 24 weeks. The primary endpoint of this study is the percentage of patients achieving sustained virologic response at post-treatment week 12 (SVR12).

RESULTS

In part 1 of the study, 95.5% (21/22) of patients achieved SVR12, and in part 2, the SVR12 rate was 85.7% (6/7). Most adverse events (AEs) were mild and moderate in severity. Two serious AEs occurred and were assessed as not being related to study drug, of which one resulted in study drug discontinuation. Two patients experienced grade 3 elevations of serum alanine aminotransferase, and no other grade ≥3 laboratory abnormalities were observed.

CONCLUSION

The multi-targeted regimen of OBV/PTV/r + DSV ± SOF with or without RBV was effective in the treatment of patients who failed previous DAA regimens including NS3/4A protease and NS5A and NS5B polymerase inhibitors. These results provide a promising outcome for patients that traditionally had limited treatment options.

Glecaprevir/pibrentasvir for the treatment of chronic hepatitis C virus infection

In recent years, management of chronic hepatitis C virus (HCV) infection has been revolutionized by the availability of oral direct-acting antivirals (DAAs), which have significantly better efficacy and safety profiles than interferon-containing regimens. Simple, short-duration DAA therapies will facilitate expansion of HCV treatment to nonspecialist providers, which will be vital to achieve the WHO target of eliminating chronic HCV as a major public health threat by 2030. Coformulated glecaprevir/pibrentasvir is the only 8-week, pan-genotypic, 2-DAA regimen recommended by international guidelines as a first-line regimen in treatment-naive, noncirrhotic HCV genotype 1-6 patients. This review provides a comprehensive summary of the pharmacodynamic and pharmacokinetic parameters, efficacy, safety and place in the HCV treatment paradigm for glecaprevir/pibrentasvir.

Efficacy and Safety of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir ± Ribavirin for HCV in Brazilian Adults with Advanced Fibrosis

INTRODUCTION AND AIM

Approximately 650,000 people in Brazil have chronic hepatitis C virus (HCV) infection. We evaluated the safety and efficacy of ombitasvir (OBV)/paritaprevir (PTV)/ritonavir (r) plus dasabuvir (DSV) with/without ribavirin (RBV) in an openlabel multicenter phase 3b trial in treatment-naive or interferon (IFN) treatment-experienced Brazilian patients with advanced hepatic fibrosis (METAVIR F3/4) and HCV genotype (GT) 1 infection.

MATERIAL AND METHODS

All patients received coformulated OBV/PTV/r daily + DSV twice daily (3-DAA). GT1a-infected patients received 3-DAA plus RBV for 12 weeks, except for prior pegIFN/RBV nonresponders with cirrhosis who were treated for 24 weeks. GT1b-infected patients received 3-DAA alone (F3) or in combination with RBV (F4) for 12 weeks. The primary endpoint was sustained virologic response (HCV RNA &lt; 15 IU/mL) at post-treatment Week 12 (SVR12).

RESULTS

The study enrolled 222 patients, 214 achieved an SVR12 (96.4%; 95% CI, 93.1-98.2%), one GT1a-infected patient experienced virologic breakthrough, six (5 GT1a) relapsed, and one was lost to follow-up. SVR12 was achieved in 111/ 112 (99.1%) GT1b-infected patients, including 42/43 (97.7%) noncirrhotic, and 69/69 (100%) cirrhotic patients; and in 103/110 (93.6%) GT1a-infected patients, including 44/46 (95.7%) noncirrhotic and 59/64 (92.2%) cirrhotic patients. Overall there was a low rate of serious adverse events (n = 6, 2.7%). One patient experienced a treatment-related serious adverse event and one patient discontinued treatment because of an adverse event.

DISCUSSION

The results confirm that the 3-DAA regimen with/without RBV is well tolerated and had a favorable safety profile and is efficacious in GT1-infected patients with advanced fibrosis (METAVIR F3/4).

Hepatitis C virus genetic diversity by geographic region within genotype 1-6 subtypes among patients treated with glecaprevir and pibrentasvir

Hepatitis C virus (HCV) is genetically diverse and includes 7 genotypes and 67 confirmed subtypes, and the global distribution of each HCV genotype (GT) varies by geographic region. In this report, we utilized a large dataset of NS3/4A and NS5A sequences isolated from 2348 HCV GT1-6-infected patients treated with the regimen containing glecaprevir/pibrentasvir (GLE/PIB) to assess genetic diversity within HCV subtypes by geographic region using phylogenetic analyses, and evaluated the prevalence of baseline amino acid polymorphisms in NS3 and NS5A by region/country and phylogenetic cluster. Among 2348 NS3/4A and NS5A sequences, phylogenetic analysis identified 6 genotypes and 44 subtypes, including 3 GT1, 8 GT2, 3 GT3, 13 GT4, 1 GT5, and 16 GT6 subtypes. Phylogenetic analysis of HCV subtype 1a confirmed the presence of two clades, which differed by geographic region distribution and NS3 Q80K prevalence. We detected phylogenetic clustering by country in HCV subtypes 1a, 1b, 2a, 2b, and 5a, suggesting that genetically distinct virus lineages are circulating in different countries. In addition, two clades were detected in HCV GT4a and GT6e, and NS5A amino acid polymorphisms were differentially distributed between the 2 clades in each subtype. The prevalence of NS3 and NS5A baseline polymorphisms varied substantially by genotype and subtype; therefore, we also determined the activity of GLE or PIB against replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples representing 6 genotypes and 21 subtypes overall. GLE and PIB retained activity against the majority of HCV replicons containing NS3/4A or NS5A from HCV GT1-6 clinical samples, with a median EC50 of 0.29 nM for GLE and 1.1 pM for PIB in a transient replicon assay. The data presented in this report expands the available data on HCV epidemiology, subtype diversity by geographic region, and NS3 and NS5A baseline polymorphism prevalence.

Pooled Resistance Analysis in Patients with Hepatitis C Virus Genotype 1 to 6 Infection Treated with Glecaprevir-Pibrentasvir in Phase 2 and 3 Clinical Trials

Over 2,200 patients infected with hepatitis C virus (HCV) genotypes (GT) 1 to 6, with or without cirrhosis, who were treatment naive or experienced to interferon, ribavirin, and/or sofosbuvir were treated with glecaprevir/pibrentasvir for 8, 12, or 16 weeks in eight registrational phase 2 and 3 clinical studies. High rates of sustained virologic response at 12 weeks postdosing (SVR12) were achieved with a <1% virologic failure (VF) rate. The prevalence of baseline polymorphisms (BPs) in NS3 at amino acid position 155 or 168 was low (<3%) in patients infected with GT1, GT2, GT3, GT4, and GT6, while 41.9% of the GT5-infected patients had NS3-D168E; BPs were not detected at position 156 in NS3. The prevalence of NS5A-BPs was high across genotypes, driven by common polymorphisms at amino acid position 30 or 31 in GT2, 58 in GT4, and 28 in GT6. The prevalence of NS5A T/Y93 polymorphisms was 5.5% in GT1, 4.9% in GT3, and 12.5% in GT6. Consistent with the activity of glecaprevir and pibrentasvir against most amino acid polymorphisms in vitro, BPs in NS3 and/or NS5A did not have an impact on treatment outcome for patients infected with GT1 to GT6, with the exception of treatment-experienced GT3-infected patients treated for 12 weeks, for whom a 16-week regimen of glecaprevir/pibrentasvir was required to achieve SVR12 rates of ≥95%. Among the 22 patients experiencing VF, treatment-emergent substitutions were detected in NS3 in 50% of patients and in NS5A in 82% of patients, frequently as a combination of substitutions that conferred resistance to glecaprevir and/or pibrentasvir. The glecaprevir/pibrentasvir regimen, when the recommended durations are used, allows for a pan-genotypic treatment option without the need for baseline resistance testing.

Characterization of demographics and NS5A genetic diversity for hepatitis C virus genotype 4-infected patients with or without cirrhosis treated with ombitasvir/paritaprevir/ritonavir

Hepatitis C virus (HCV) genotype 4 (GT4) is genetically diverse with 17 confirmed and 4 provisional subtypes. In this report, HCV GT4-infected patient samples from Phase 2/3 clinical studies were analysed to characterize global demographics and genetic diversity of GT4 infection among patients treated with ombitasvir (OBV, NS5A inhibitor) plus paritaprevir/r (NS3/4A inhibitor codosed with ritonavir). Among 17 subtypes isolated from GT4-infected patients in the PEARL-I and AGATE-I studies, subtype prevalence by country of enrolment and country of origin suggested that subtypes 4a and 4d were likely circulating in Europe, while heterogeneous GT4 subtypes and a portion of GT4a detected in European and North American countries were likely due to immigration of HCV-infected patients from Africa. The distributions of birth cohort and race were also significantly different across GT4 subtypes 4a, 4d, and non-4a/4d. In addition, phylogenetic analyses of NS5A sequences revealed clustering within subtype 4a which segregated by the patient-reported country of origin and the presence of the L30R/S polymorphism. HCV NS5A sequences derived from GT4a-infected patients who originated from Europe and the United States clustered separately from sequences derived from patients who originated from Egypt, suggesting that genetically distinct strains of subtype 4a may be circulating globally. Finally, NS5A baseline polymorphisms were frequently detected at amino acid positions of interest for the inhibitor-class and OBV retained activity against 37 of 39 NS5A GT4 clinical isolates, with no impact on treatment outcome in the PEARL-I and AGATE-I studies.

Resistance Analysis of a 3-Day Monotherapy Study with Glecaprevir or Pibrentasvir in Patients with Chronic Hepatitis C Virus Genotype 1 Infection

Glecaprevir (an NS3/4A protease inhibitor) and pibrentasvir (an NS5A inhibitor) are potent and pangenotypic hepatitis C virus (HCV) direct-acting antivirals. This report describes the baseline polymorphisms and treatment-emergent substitutions in NS3 or NS5A detected in samples from HCV genotype 1-infected patients receiving 3-day monotherapy of glecaprevir or pibrentasvir, respectively. None of the NS3 polymorphisms detected in the 47 baseline samples collected prior to glecaprevir monotherapy conferred reduced susceptibility to glecaprevir. The NS3 A156T substitution, which conferred resistance to glecaprevir but had low replication efficiency, emerged in one genotype 1a-infected patient among the 35 patients with available post-baseline sequence data. Baseline NS5A polymorphisms were detected in 12 of 40 patients prior to pibrentasvir monotherapy; most polymorphisms were single-position NS5A amino acid substitutions that did not confer resistance to pibrentasvir. Among the 19 patients with available post-baseline NS5A sequence data, 3 had treatment-emergent NS5A substitutions during pibrentasvir monotherapy. All treatment-emergent NS5A substitutions were linked multiple-position, almost exclusively double-position, substitutions that conferred resistance to pibrentasvir. Replicons engineered with these double-position substitutions had low replication efficiency. In conclusion, resistance-conferring substitutions emerged in a small number of genotype 1-infected patients during glecaprevir or pibrentasvir monotherapy; unlike other NS5A inhibitors, pibrentasvir did not select single-position NS5A substitutions during monotherapy.

Highlights of the Structure-Activity Relationships of Benzimidazole Linked Pyrrolidines Leading to the Discovery of the Hepatitis C Virus NS5A Inhibitor Pibrentasvir (ABT-530)

Curative interferon and ribavirin sparing treatments for hepatitis C virus (HCV)-infected patients require a combination of mechanistically orthogonal direct acting antivirals. A shared component of these treatments is usually an HCV NS5A inhibitor. First generation FDA approved treatments, including the component NS5A inhibitors, do not exhibit equivalent efficacy against HCV virus genotypes 1-6. In particular, these first generation NS5A inhibitors tend to select for viral drug resistance. Ombitasvir is a first generation HCV NS5A inhibitor included as a key component of Viekira Pak for the treatment of patients with HCV genotype 1 infection. Since the launch of next generation HCV treatments, functional cure for genotype 1-6 HCV infections has been achieved, as well as shortened treatment duration across a wider spectrum of genotypes. In this paper, we show how we have modified the anchor, linker, and end-cap architecture of our NS5A inhibitor design template to discover a next generation NS5A inhibitor pibrentasvir (ABT-530), which exhibits potent inhibition of the replication of wild-type genotype 1-6 HCV replicons, as well as improved activity against replicon variants demonstrating resistance against first generation NS5A inhibitors.

Efficacy and safety results of patients with HCV genotype 2 or 3 infection treated with ombitasvir/paritaprevir/ritonavir and sofosbuvir with or without ribavirin (QUARTZ II-III)

The efficacy and safety of an investigational combination of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r) plus sofosbuvir (SOF) ± ribavirin (RBV) in patients with HCV genotype 2 or 3 infection with or without cirrhosis was evaluated. Patients with HCV genotype 3 infection without cirrhosis were randomized to receive OBV/PTV/r + SOF ± RBV for 12 weeks; OBV/PTV/r + SOF + RBV was administered to genotype 3-infected patients with cirrhosis for 12 weeks and to genotype 2-infected patients without cirrhosis for either 6 or 8 weeks. Efficacy was assessed by sustained virologic response [HCV RNA <25 IU/mL] 12 weeks post-treatment (SVR12). Safety was assessed in all treated patients. In patients with genotype 3 infection with or without cirrhosis treated with 12 weeks of OBV/PTV/r + SOF ± RBV, the overall SVR12 rate was 98% (50/51), with no virologic failures. Patients with genotype 2 infection treated with OBV/PTV/r + SOF + RBV had SVR12 rates of 90% (9/10) and 44% (4/9) following 8- and 6-week treatment durations, respectively; failure to achieve SVR12 for these patients was due to relapse without baseline or treatment-emergent resistance-associated substitutions. Thus, the investigational combination of OBV/PTV/r with SOF ± RBV was well tolerated and achieved high SVR rates with no virologic failures in patients with genotype 3 infection. Combining direct-acting antivirals with complementary mechanisms of action and different viral targets may be an effective treatment strategy that may allow for shorter durations of therapy.

Integrated Resistance Analysis of CERTAIN-1 and CERTAIN-2 Studies in Hepatitis C Virus-Infected Patients Receiving Glecaprevir and Pibrentasvir in Japan

Glecaprevir and pibrentasvir are hepatitis C virus (HCV) pangenotypic inhibitors targeting NS3/4A protease and NS5A, respectively. This once-daily, fixed-dose combination regimen demonstrated high sustained virologic response 12 weeks postdosing (SVR12) rates in CERTAIN-1 and CERTAIN-2 studies in Japanese HCV-infected patients, with a low virologic failure rate (1.2%). There were no virologic failures among direct-acting antiviral (DAA)-treatment-naive genotype 1a (GT1a) (n = 4)-, GT1b (n = 128)-, and GT2 (n = 97)-infected noncirrhotic patients treated for 8 weeks or among GT1b (n = 38)- or GT2 (n = 20)-infected patients with compensated cirrhosis treated for 12 weeks. Two of 33 DAA-experienced and 2 of 12 GT3-infected patients treated for 12 weeks experienced virologic failure. Pooled resistance analysis, grouped by HCV subtype, treatment duration, prior treatment experience, and cirrhosis status, was conducted. Among DAA-naive GT1b-infected patients, the baseline prevalence of NS3-D168E was 1.2%, that of NS5A-L31M was 3.6%, and that of NS5A-Y93H was 17.6%. Baseline polymorphisms in NS3 or NS5A were less prevalent in GT2, with the exception of the common L/M31 polymorphism in NS5A. Among DAA-experienced GT1b-infected patients (30/32 daclatasvir plus asunaprevir-experienced patients), the baseline prevalence of NS3-D168E/T/V was 48.4%, that of NS5A-L31F/I/M/V was 81.3%, that of the NS5A P32deletion was 6.3%, and that of NS5A-Y93H was 59.4%. Common baseline polymorphisms in NS3 and/or NS5A had no impact on treatment outcomes in GT1- and GT2-infected patients; the impact on GT3-infected patients could not be assessed due to the enrollment of patients infected with diverse subtypes and the limited number of patients. The glecaprevir-pibrentasvir combination regimen allows a simplified treatment option without the need for HCV subtyping or baseline resistance testing for DAA-naive GT1- or GT2-infected patients. (The CERTAIN-1 and CERTAIN-2 studies have been registered at ClinicalTrials.gov under identifiers NCT02707952 and NCT02723084, respectively.).

Glecaprevir-Pibrentasvir for 8 or 12 Weeks in HCV Genotype 1 or 3 Infection

BACKGROUND

Glecaprevir and pibrentasvir are direct-acting antiviral agents with pangenotypic activity and a high barrier to resistance. We evaluated the efficacy and safety of 8-week and 12-week courses of treatment with 300 mg of glecaprevir plus 120 mg of pibrentasvir in patients without cirrhosis who had hepatitis C virus (HCV) genotype 1 or 3 infection.

METHODS

We conducted two phase 3, randomized, open-label, multicenter trials. Patients with genotype 1 infection were randomly assigned in a 1:1 ratio to receive once-daily glecaprevir-pibrentasvir for either 8 or 12 weeks. Patients with genotype 3 infection were randomly assigned in a 2:1 ratio to receive 12 weeks of treatment with either glecaprevir-pibrentasvir or sofosbuvir-daclatasvir. Additional patients with genotype 3 infection were subsequently enrolled and nonrandomly assigned to receive 8 weeks of treatment with glecaprevir-pibrentasvir. The primary end point was the rate of sustained virologic response 12 weeks after the end of treatment.

RESULTS

In total, 1208 patients were treated. The rate of sustained virologic response at 12 weeks among genotype 1-infected patients was 99.1% (95% confidence interval [CI], 98 to 100) in the 8-week group and 99.7% (95% CI, 99 to 100) in the 12-week group. Genotype 3-infected patients who were treated for 12 weeks had a rate of sustained virologic response at 12 weeks of 95% (95% CI, 93 to 98; 222 of 233 patients) with glecaprevir-pibrentasvir and 97% (95% CI, 93 to 99.9; 111 of 115) with sofosbuvir-daclatasvir; 8 weeks of treatment with glecaprevir-pibrentasvir yielded a rate of 95% (95% CI, 91 to 98; 149 of 157 patients). Adverse events led to discontinuation of treatment in no more than 1% of patients in any treatment group.

CONCLUSIONS

Once-daily treatment with glecaprevir-pibrentasvir for either 8 weeks or 12 weeks achieved high rates of sustained virologic response among patients with HCV genotype 1 or 3 infection who did not have cirrhosis. (Funded by AbbVie; ENDURANCE-1 and ENDURANCE-3 ClinicalTrials.gov numbers, NCT02604017 and NCT02640157 .).

In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS3/4A Protease Inhibitor Glecaprevir

Glecaprevir (formerly ABT-493) is a novel hepatitis C virus (HCV) NS3/4A protease inhibitor (PI) with pangenotypic activity. It inhibited the enzymatic activity of purified NS3/4A proteases from HCV genotypes 1 to 6 in vitro (half-maximal [50%] inhibitory concentration = 3.5 to 11.3 nM) and the replication of stable HCV subgenomic replicons containing proteases from genotypes 1 to 6 (50% effective concentration [EC50] = 0.21 to 4.6 nM). Glecaprevir had a median EC50 of 0.30 nM (range, 0.05 to 3.8 nM) for HCV replicons containing proteases from 40 samples from patients infected with HCV genotypes 1 to 5. Importantly, glecaprevir was active against the protease from genotype 3, the most-difficult-to-treat HCV genotype, in both enzymatic and replicon assays demonstrating comparable activity against the other HCV genotypes. In drug-resistant colony selection studies, glecaprevir generally selected substitutions at NS3 amino acid position A156 in replicons containing proteases from genotypes 1a, 1b, 2a, 2b, 3a, and 4a and substitutions at position D/Q168 in replicons containing proteases from genotypes 3a, 5a, and 6a. Although the substitutions A156T and A156V in NS3 of genotype 1 reduced susceptibility to glecaprevir, replicons with these substitutions demonstrated a low replication efficiency in vitro Glecaprevir is active against HCV with most of the common NS3 amino acid substitutions that are associated with reduced susceptibility to other currently approved HCV PIs, including those at positions 155 and 168. Combination of glecaprevir with HCV inhibitors with other mechanisms of action resulted in additive or synergistic antiviral activity. In summary, glecaprevir is a next-generation HCV PI with potent pangenotypic activity and a high barrier to the development of resistance.

Resistance characterization of hepatitis C virus genotype 2 from Japanese patients treated with ombitasvir and paritaprevir/ritonavir

Treatment of HCV genotype (GT) 2‐infected Japanese patients with paritaprevir (NS3/4A inhibitor boosted with ritonavir) and ombitasvir (NS5A inhibitor) without ribavirin for 12 weeks in the phase 2 study M12‐536, and with ribavirin for 16 weeks in phase 3 study GIFT II resulted in SVR rates of 72.2% to 91.5%. Overall, 11 out of 125 patients with GT2a and 37 out of 79 patients with GT2b infection experienced virologic failure. The prevalence of baseline polymorphisms in NS3 and NS5A and their the impact on treatment outcome, as well as the development of viral resistance in GT2‐infected patients experiencing virologic failure were evaluated by HCV NS3 and NS5A population and clonal sequence analyses. Baseline polymorphisms in NS3 that confer resistance to paritaprevir were rare in both GT2a‐ and GT2b‐infected patients, while baseline polymorphisms in NS5A that confer resistance to ombitasvir were detected in 11.2% and 14.1% of the GT2a‐ and GT2b‐infected patients, respectively. There was no significant impact of baseline polymorphisms on treatment outcome in Japanese patients. The most common treatment‐emergent substitutions at the time of virologic failure occurred at amino acid positions 168 in NS3 and 28 in NS5A in both GT2a‐ and GT2b‐infected patients. Although there was a higher rate of virologic failure in patients with GT2b infection, the resistance analyses presented in this report support the conclusion that testing for baseline resistance‐associated polymorphisms is not warranted for HCV GT2‐infected patients treated with a regimen of ombitasvir/paritaprevir/ritonavir + ribavirin for 16 weeks.

Safety and Efficacy of Ombitasvir, Paritaprevir With Ritonavir ± Dasabuvir With or Without Ribavirin in Patients With Human Immunodeficiency Virus-1 and Hepatitis C Virus Genotype 1 or Genotype 4 Coinfection: TURQUOISE-I Part 2

BACKGROUND

Ombitasvir, paritaprevir with ritonavir, and dasabuvir (OBV/PTV/r ± DSV) ±ribavirin (RBV) are approved to treat hepatitis C virus (HCV) genotype 1 and 4 infection. Here, we investigate the safety and efficacy of OBV/PTV/r + DSV ±RBV for HCV genotype 1, and OBV/PTV/r + RBV for HCV genotype 4, in human immunodeficiency virus (HIV)-1 coinfected patients with or without compensated cirrhosis.

METHODS

TURQUOISE-I, Part 2 is a phase 3 multicenter study. Patients with or without cirrhosis were HCV treatment-naive or -experienced, on an HIV-1 antiretroviral regimen containing atazanavir, raltegravir, dolutegravir, or darunavir (for genotype 4 only), and had plasma HIV-1 ribonucleic acid <40 copies/mL at screening. Patients received OBV/PTV/r ± DSV ±RBV for 12 or 24 weeks.

RESULTS

In total, 228 patients were treated according to guidelines. Sustained virologic response at posttreatment week 12 (SVR12) was achieved by 194 of 200 (97%) and 27 of 28 (96%) patients with HCV genotype 1 and genotype 4 infection, respectively. There were 2 virologic failures: 1 breakthrough and 1 relapse in a cirrhotic and a noncirrhotic patient with genotype 1b and 1a infection, respectively. One reinfection occurred at posttreatment week 12 in a genotype 1a-infected patient. Excluding nonvirologic failures, the SVR12 rates were 98% (genotype 1) and 100% (genotype 4). Adverse events were mostly mild in severity and did not lead to discontinuation. Laboratory abnormalities were rare.

CONCLUSIONS

The OBV/PTV/r ±DSV was well tolerated and yielded high SVR12 rates in patients with HCV genotype 1 or genotype 4/HIV-1 coinfection. The OBV/PTV/r ± DSV ±RBV is a potent HCV treatment option for patients with HIV-1 coinfection, regardless of treatment experience.

Discovery of fluorobenzimidazole HCV NS5A inhibitors

Research toward a next-generation HCV NS5A inhibitor has identified fluorobenzimidazole analogs that demonstrate potent, broad-genotype in vitro activity against HCV genotypes 1-6 replicons as well as HCV NS5A variants that are orders of magnitude less susceptible to inhibition by first-generation NS5A inhibitors in comparison to wild-type replicons. The fluorobenzimidazole inhibitors have improved pharmacokinetic properties in comparison to non-fluorinated benzimidazole analogs. Discovery of these inhibitors was facilitated by exploring SAR in a structurally simplified inhibitor series.

Ombitasvir, paritaprevir, and ritonavir plus ribavirin in adults with hepatitis C virus genotype 4 infection and cirrhosis (AGATE-I): a multicentre, phase 3, randomised open-label trial

BACKGROUND

Hepatitis C virus (HCV) genotype 4 infection is most commonly reported in sub-Saharan Africa and the Middle East; however, prevalence is increasing worldwide through immigration. HCV genotype 4 accounts for 20% of all infections, but clinical trial data for treatment remain limited. We assessed the combination of two direct-acting antivirals, ombitasvir (NS5A inhibitor) and paritaprevir (NS3/4A protease inhibitor; co-dosed with ritonavir) plus ribavirin in patients with HCV genotype 4 infection and compensated cirrhosis.

METHODS

In this multicentre, randomised, open-label phase 3 trial (AGATE-I), treatment-naive and interferon or pegylated interferon and ribavirin treatment-experienced patients with HCV genotype 4 infection and compensated cirrhosis were recruited from academic, public, and private hospitals in Austria, Belgium, Canada, France, Germany, Greece, Italy, and the USA. Key eligibility criteria were age 18 years or older, with chronic HCV infection assessed by the presence of anti-HCV antibodies or HCV RNA. Patients were randomly assigned (1:1) to receive 25 mg ombitasvir, 150 mg paritaprevir, and 100 mg ritonavir once daily, with weight-based ribavirin dosed twice daily for either 12 weeks or 16 weeks. Randomisation was stratified by HCV treatment history (treatment-experienced vs treatment-naive patients) and further stratified by type of non-response to previous HCV treatment (null responders, partial responders, or relapsers) for treatment-experienced patients. Treatments were assigned by an interactive response technology system with computer-generated randomisation lists prepared by personnel from the study's funding sponsor who were not involved with the conduct of the study or with data analysis. The primary outcome was the proportion of patients with a sustained virological response (HCV RNA <25 IU/mL) at post-treatment week 12 (SVR12) in the intention-to-treat population, with the lower 97·5% CI compared with a clinically relevant threshold (67%; based on SVR reported for pegylated interferon and ribavirin) to achieve superiority. The safety population included all patients who received at least one dose of study drug, and safety analyses were done by the treatment duration received (12 weeks or 16 weeks). Data presented are from the planned primary interim analysis of part one of the study when all patients enrolled in part one had reached post-treatment week 12 or prematurely discontinued from the study. This trial is registered with ClinicalTrials.gov, number NCT02265237, and part two of the trial is ongoing but closed to new participants.

FINDINGS

Between Nov 18, 2014, and May 19, 2015, we enrolled 120 eligible patients, with 59 patients assigned to receive 12 weeks of treatment and 61 patients assigned to receive 16 weeks of treatment with ombitasvir, paritaprevir, and ritonavir plus ribavirin. One patient in the 12-week group experienced virological breakthrough and one discontinued prematurely after the first day of treatment. One patient missed the post-treatment week 12 visit in the 16-week group. SVR12 was achieved in 57 (97%; 97·5% CI 86·7-99·2) of 59 patients in the 12-week group and 60 (98%; 89·6-99·8) of 61 in the 16-week group. Adverse events in more than 10% of all patients were asthenia (11 [18%] of 60 in the 12-week group; 19 [32%] of 60 in the 16-week group), fatigue (ten [17%] in the 12-week group; 20 [33%] in the 16-week group), headache (14 [23%] in the 12-week group; 14 [23%] in the 16-week group), anaemia (nine [15%] in the 12-week group; 12 [20%] in the 16-week group), pruritus (five [8%] in the 12-week group; 14 [23%] in the 16-week group), nausea (six [10%] in the 12-week group; eight [13%] in the 16-week group), and dizziness (four [7%] in the 12-week group; nine [15%] in the 16-week group).

INTERPRETATION

With SVR12 achieved in a high proportion of patients, no post-treatment relapses, and a similar adverse event profile for the 12-week and 16-week treatment groups, extending treatment with ombitasvir, paritaprevir, and ritonavir plus ribavirin beyond 12 weeks seems to have no additional benefit for patients with HCV genotype 4 infection and compensated cirrhosis and might not be necessary for this patient group.

FUNDING

AbbVie.

Hepatitis C virus drug resistance-associated substitutions: State of the art summary

Hepatitis C virus (HCV) drug development has resulted in treatment regimens composed of interferon-free, all-oral combinations of direct-acting antivirals. While the new regimens are potent and highly efficacious, the full clinical impact of HCV drug resistance, its implications for retreatment, and the potential role of baseline resistance testing remain critical research and clinical questions. In this report, we discuss the viral proteins targeted by HCV direct-acting antivirals and summarize clinically relevant resistance data for compounds that have been approved or are currently in phase 3 clinical trials.

CONCLUSION

This report provides a comprehensive, systematic review of all resistance information available from sponsors' trials as a tool to inform the HCV drug development field.

Efficacy and Safety of Ombitasvir, Paritaprevir, and Ritonavir in an Open-Label Study of Patients With Genotype 1b Chronic Hepatitis C Virus Infection With and Without Cirrhosis

BACKGROUND & AIMS

Interferon-free treatment options are rapidly evolving for patients with chronic hepatitis C virus (HCV) genotype 1b (GT1b) infection with cirrhosis and for nonresponders to prior pegylated interferon and ribavirin therapy. We performed a phase 2b, open-label trial of the combination of ombitasvir (a NS5A replication complex inhibitor), paritaprevir, and ritonavir (an NS3/4A protease inhibitor)-an interferon- and ribavirin-free regimen-in difficult-to-treat patients, including prior null responders and patients with cirrhosis.

METHODS

In an international study, 82 patients without cirrhosis (42 treatment-naive and 40 prior null responders) and 99 with cirrhosis (47 treatment-naive and 52 treatment-experienced with prior relapse or a null or partial response) with chronic HCV GT1b infection received ombitasvir (25 mg), paritaprevir (150 mg), and ritonavir (100 mg) once daily for 12 weeks (without cirrhosis) or 24 weeks (with cirrhosis). The primary efficacy endpoint was sustained virologic response 12 weeks after the end of treatment (SVR12).

RESULTS

In treatment-naive and null responder patients without cirrhosis, rates of SVR12 were 95.2% and 90.0%, respectively. In treatment-naive and treatment-experienced patients with cirrhosis, rates of SVR12 were 97.9% and 96.2%, respectively. No clinically meaningful differences in rates of SVR12 were observed between patients with or without cirrhosis. Virologic relapse occurred in 3 null responders without cirrhosis and 1 with cirrhosis; virologic breakthrough occurred in 1 null responder without cirrhosis. Common adverse events included headache, asthenia, pruritus, and diarrhea. One patient discontinued taking the drugs because of treatment-related adverse events.

CONCLUSIONS

An interferon- and ribavirin-free regimen of ombitasvir, paritaprevir, and ritonavir, achieved high rates of SVR12 in patients with HCV GT1b infection with and without cirrhosis. This regimen was well tolerated and was associated with low rates of treatment discontinuation. ClinicalTrials.gov no: NCT01685203.

Ombitasvir plus paritaprevir plus ritonavir with or without ribavirin in treatment-naive and treatment-experienced patients with genotype 4 chronic hepatitis C virus infection (PEARL-I): a randomised, open-label trial

BACKGROUND

Hepatitis C virus (HCV) genotype 4 accounts for about 13% of global HCV infections. Because interferon-containing treatments for genotype 4 infection have low efficacy and poor tolerability, an unmet need exists for effective all-oral regimens. We examined the efficacy and safety of an all-oral interferon-free regimen of ombitasvir, an NS5A inhibitor, and paritaprevir (ABT-450), an NS3/4A protease inhibitor dosed with ritonavir (ombitasvir plus paritaprevir plus ritonavir), given with or without ribavirin.

METHODS

In this multicentre ongoing phase 2b, randomised, open-label combination trial (PEARL-I), patients were recruited from academic, public, and private hospitals and clinics in France, Hungary, Italy, Poland, Romania, Spain, Turkey, and the USA. Eligible participants were aged 18-70 years with non-cirrhotic, chronic HCV genotype 4 infection (documented ≥6 months before screening) and plasma HCV RNA levels higher than 10,000 IU/mL. Previously untreated (treatment-naive) patients were randomly assigned (1:1) by computer-generated randomisation lists to receive once-daily ombitasvir (25 mg) plus paritaprevir (150 mg) plus ritonavir (100 mg) with or without weight-based ribavirin for 12 weeks. Previously treated (treatment-experienced) patients who had received pegylated interferon plus ribavirin all received the ribavirin-containing regimen. The primary endpoint was a sustained virological response (HCV RNA <25 IU/mL) 12 weeks after the end of treatment (SVR12). Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01685203.

FINDINGS

Between Aug 14, 2012, and Nov 19, 2013, 467 patients with HCV infection were screened, of whom 174 were infected with genotype 4. 135 patients were randomly assigned to treatment and received at least one dose of study medication; 86 patients were treatment-naive, of whom 44 received ombitasvir plus paritaprevir plus ritonavir and 42 received ombitasvir plus paritaprevir plus ritonavir with ribavirin, and 49 treatment-experienced patients received the ribavirin-containing regimen. In previously untreated patients, SVR12 rates were 100% (42/42 [95% CI 91·6-100]) in the ribavirin-containing regimen and 90·9% (40/44 [95% CI 78·3-97·5]) in the ribavirin-free regimen. No statistically significant differences in SVR12 rates were noted between the treatment-naive groups (mean difference -9·16% [95% CI -19·61 to 1·29]; p=0·086). All treatment-experienced patients achieved SVR12 (49/49; 100% [95% CI 92·7-100]). In the ribavirin-free group, two (5%) of 42 treatment-naive patients had virological relapse, and one (2%) of 44 had virological breakthrough; no virological failures were recorded in the ribavirin-containing regimen. The most common adverse event was headache (14 [29%] of 49 treatment-experienced patients and 14 [33%] of 42 treatment-naive patients). No adverse event-related discontinuations or dose interruptions of study medications, including ribavirin, were noted, and only four patients (4%) of 91 receiving ribavirin required dose modification for haemoglobin less than 100 g/L or anaemia.

INTERPRETATION

An interferon-free regimen of ombitasvir plus paritaprevir plus ritonavir with or without ribavirin achieved high sustained virological response rates at 12 weeks after the end of treatment and was generally well tolerated, with low rates of anaemia and treatment discontinuation in non-cirrhotic previously untreated and previously treated patients with HCV genotype 4 infection.

FUNDING

AbbVie.

Ombitasvir, paritaprevir co-dosed with ritonavir, dasabuvir, and ribavirin for hepatitis C in patients co-infected with HIV-1: a randomized trial

IMPORTANCE

Patients co-infected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) are at high risk for liver disease progression. However, interferon-based treatments for HCV infection have significant toxicities, limiting treatment uptake.

OBJECTIVE

To assess the all-oral 3 direct-acting antiviral (3D) regimen of ombitasvir, paritaprevir (co-dosed with ritonavir [paritaprevir/r]), dasabuvir, and ribavirin in HCV genotype 1-infected adults with HIV-1 co-infection, including patients with cirrhosis.

DESIGN, SETTING, AND PARTICIPANTS

TURQUOISE-I is a randomized, open-label study. Part 1a of this pilot study was conducted at 17 sites in the United States and Puerto Rico between September 2013 and August 2014 and included 63 patients with HCV genotype 1 and HIV-1 co-infection who were HCV treatment-naive or had history of prior treatment failure with peginterferon plus ribavirin therapy. The study allowed enrollment of patients, including those with cirrhosis, with a CD4+ count of 200/mm3 or greater or CD4+ percentage of 14% or more and plasma HIV-1 RNA suppressed while taking a stable atazanavir- or raltegravir-inclusive antiretroviral regimen.

INTERVENTIONS

Ombitasvir/paritaprevir/r, dasabuvir, and ribavirin for 12 or 24 weeks of treatment as randomized.

MAIN OUTCOMES AND MEASURES

The primary assessment was the proportion of patients with sustained virologic response (HCV RNA <25 IU/mL) at posttreatment week 12 (SVR12).

RESULTS

Among patients receiving 12 or 24 weeks of 3D and ribavirin, SVR12 was achieved by 29 of 31 (94%; 95% CI, 79%-98%) and 29 of 32 patients (91%; 95% CI, 76%-97%), respectively. Of the 5 patients who did not achieve SVR, 1 withdrew consent, 2 had confirmed virologic relapse or breakthrough, and 2 patients had clinical history and phylogenetic evidence consistent with HCV reinfection. The most common treatment-emergent adverse events were fatigue (48%), insomnia (19%), nausea (18%), and headache (16%). Adverse events were generally mild, with none reported as serious or leading to discontinuation. No patient had a confirmed HIV-1 breakthrough of 200 copies/mL or greater during treatment.

CONCLUSIONS AND RELEVANCE

In this open-label, randomized uncontrolled study, treatment with the all-oral, interferon-free 3D-plus-ribavirin regimen resulted in high SVR rates among patients co-infected with HCV genotype 1 and HIV-1 whether treated for 12 or 24 weeks. Further phase 3 studies of this regimen are warranted in patients with co-infection.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01939197.

An interferon-free antiviral regimen for HCV after liver transplantation

BACKGROUND

Hepatitis C virus (HCV) infection is the leading indication for liver transplantation worldwide, and interferon-containing regimens are associated with low response rates owing to treatment-limiting toxic effects in immunosuppressed liver-transplant recipients. We evaluated the interferon-free regimen of the NS5A inhibitor ombitasvir coformulated with the ritonavir-boosted protease inhibitor ABT-450 (ABT-450/r), the nonnucleoside NS5B polymerase inhibitor dasabuvir, and ribavirin in liver-transplant recipients with recurrent HCV genotype 1 infection.

METHODS

We enrolled 34 liver-transplant recipients with no fibrosis or mild fibrosis, who received ombitasvir-ABT-450/r (at a once-daily dose of 25 mg of ombitasvir, 150 mg of ABT-450, and 100 mg of ritonavir), dasabuvir (250 mg twice daily), and ribavirin for 24 weeks. Selection of the initial ribavirin dose and subsequent dose modifications for anemia were at the investigator's discretion. The primary efficacy end point was a sustained virologic response 12 weeks after the end of treatment.

RESULTS

Of the 34 study participants, 33 had a sustained virologic response at post-treatment weeks 12 and 24, for a rate of 97% (95% confidence interval, 85 to 100). The most common adverse events were fatigue, headache, and cough. Five patients (15%) required erythropoietin; no patient required blood transfusion. One patient discontinued the study drugs owing to adverse events after week 18 but had a sustained virologic response. Blood levels of calcineurin inhibitors were monitored, and dosages were modified to maintain therapeutic levels; no episode of graft rejection was observed during the study.

CONCLUSIONS

Treatment with the multitargeted regimen of ombitasvir-ABT-450/r and dasabuvir with ribavirin was associated with a low rate of serious adverse events and a high rate of sustained virologic response among liver-transplant recipients with recurrent HCV genotype 1 infection, a historically difficult-to-treat population. (Funded by AbbVie; CORAL-I ClinicalTrials.gov number, NCT01782495.).

Treatment of HCV with ABT-450/r-ombitasvir and dasabuvir with ribavirin

BACKGROUND

The interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r) and the NS5A inhibitor ombitasvir (also known as ABT-267) plus the nonnucleoside polymerase inhibitor dasabuvir (also known as ABT-333) and ribavirin has shown efficacy against the hepatitis C virus (HCV) in patients with HCV genotype 1 infection. In this phase 3 trial, we evaluated this regimen in previously untreated patients with HCV genotype 1 infection and no cirrhosis.

METHODS

In this multicenter, randomized, double-blind, placebo-controlled trial, we assigned previously untreated patients with HCV genotype 1 infection, in a 3:1 ratio, to an active regimen consisting of a single-tablet coformulation of ABT-450/r-ombitasvir (at a once-daily dose of 150 mg of ABT-450, 100 mg of ritonavir, and 25 mg of ombitasvir), and dasabuvir (250 mg twice daily) with ribavirin (in doses determined according to body weight) (group A) or matching placebos (group B). The patients received the study treatment during a 12-week double-blind period. The primary end point was sustained virologic response at 12 weeks after the end of treatment. The primary analysis compared the response rate in group A with the response rate (78%) in a historical control group of previously untreated patients without cirrhosis who received telaprevir with peginterferon and ribavirin. Adverse events occurring during the double-blind period were compared between group A and group B.

RESULTS

A total of 631 patients received at least one dose of the study drugs. The rate of sustained virologic response in group A was 96.2% (95% confidence interval, 94.5 to 97.9), which was superior to the historical control rate. Virologic failure during treatment and relapse after treatment occurred in 0.2% and 1.5%, respectively, of the patients in group A. The response rates in group A were 95.3% among patients with HCV genotype 1a infection and 98.0% among those with HCV genotype 1b infection. The rate of discontinuation due to adverse events was 0.6% in each study group. Nausea, pruritus, insomnia, diarrhea, and asthenia occurred in significantly more patients in group A than in group B (P<0.05 for all comparisons). Reductions in the hemoglobin level were all of grade 1 or 2; reductions of grade 1 and 2 occurred in 47.5% and 5.8%, respectively, of the patients in group A, whereas grade 1 reductions occurred in 2.5% of the patients in group B.

CONCLUSIONS

In previously untreated patients with HCV genotype 1 infection and no cirrhosis, a 12-week multitargeted regimen of ABT-450/r-ombitasvir and dasabuvir with ribavirin was highly effective and was associated with a low rate of treatment discontinuation. (Funded by AbbVie; SAPPHIRE-I ClinicalTrials.gov number, NCT01716585.).

Retreatment of HCV with ABT-450/r-ombitasvir and dasabuvir with ribavirin

BACKGROUND

In this phase 3 trial we evaluated the efficacy and safety of the interferon-free combination of ABT-450 with ritonavir (ABT-450/r), ombitasvir (also known as ABT-267), dasabuvir (also known as ABT-333), and ribavirin for the retreatment of HCV in patients who were previously treated with peginterferon-ribavirin.

METHODS

We enrolled patients with HCV genotype 1 infection and no cirrhosis who had previously been treated with peginterferon-ribavirin and had a relapse, a partial response, or a null response. Patients were randomly assigned in a 3:1 ratio to receive coformulated ABT-450/r-ombitasvir (at a once-daily dose of 150 mg of ABT-450, 100 mg of ritonavir, and 25 mg of ombitasvir) and dasabuvir (250 mg twice daily) with ribavirin (1000 or 1200 mg daily) or matching placebos during the 12-week double-blind period. The primary end point was the rate of sustained virologic response 12 weeks after the end of study treatment. The primary efficacy analysis compared this rate among patients assigned to the active regimen with a historical response rate (65%) among previously treated patients with HCV genotype 1 infection and no cirrhosis who had received retreatment with telaprevir and peginterferon-ribavirin.

RESULTS

A total of 394 patients received at least one study-drug dose. In the active-regimen group, 286 of 297 patients had a sustained virologic response at post-treatment week 12, for an overall rate of 96.3% (95% confidence interval, 94.2 to 98.4). This rate was noninferior and superior to the historical control rate. Rates were 95.3% among patients with a prior relapse (82 of 86 patients), 100% among patients with a prior partial response (65 of 65 patients), and 95.2% among patients with a prior null response (139 of 146 patients). Pruritus occurred more frequently with the active regimen (in 13.8% of patients) than with placebo (5.2%, P=0.03). Three patients in the active-regimen group (1.0%) discontinued the study drugs owing to adverse events. Hemoglobin values of grade 2 (8.0 to <10.0 g per deciliter) and grade 3 (6.5 to <8.0 g per deciliter) occurred in 4.7% and 0.3% of patients in the active-regimen group, respectively.

CONCLUSIONS

Rates of response to a 12-week interferon-free combination regimen were more than 95% among previously treated patients with HCV genotype 1 infection, including patients with a prior null response. (Funded by AbbVie; SAPPHIRE-II ClinicalTrials.gov number, NCT01715415.).

Phase 2b trial of interferon-free therapy for hepatitis C virus genotype 1

BACKGROUND

An interferon-free combination of the protease inhibitor ABT-450 with ritonavir (ABT-450/r), the nonnucleoside polymerase inhibitor ABT-333, and ribavirin showed efficacy against the hepatitis C virus (HCV) in a pilot study involving patients with HCV genotype 1 infection. The addition of another potent agent, the NS5A inhibitor ABT-267, may improve efficacy, especially in difficult-to-treat patients. This study was designed to evaluate multiple regimens of direct-acting antiviral agents and ribavirin in patients with HCV genotype 1 infection who had not received therapy previously or who had no response to prior therapy with pegylated interferon and ribavirin.

METHODS

In this phase 2b, open-label study with 14 treatment subgroups, 571 patients without cirrhosis who had not received treatment previously or who had not had a response to prior therapy were randomly assigned to a regimen of ABT-450/r, combined with ABT-267 or ABT-333 or both, for 8, 12, or 24 weeks and received at least one dose of therapy. All the subgroups but 1 also received ribavirin (dose determined according to body weight). The primary end point was sustained virologic response at 24 weeks after the end of treatment. The primary efficacy analysis compared rates between previously untreated patients who received three direct-acting antiviral agents and ribavirin for 8 weeks and those who received the same therapy for 12 weeks.

RESULTS

Among previously untreated patients who received three direct-acting antiviral agents (with the ABT-450/r dose administered as 150 mg of ABT-450 and 100 mg of ritonavir) plus ribavirin, the rate of sustained virologic response at 24 weeks after treatment was 88% among those who received the therapy for 8 weeks and 95% among those who received the therapy for 12 weeks (difference, -7 percentage points; 95% confidence interval, -19 to 5; P=0.24). The rates of sustained virologic response across all treatment subgroups ranged from 83 to 100%. The most frequent adverse events were fatigue, headache, nausea, and insomnia. Eight patients (1%) discontinued treatment owing to adverse events.

CONCLUSIONS

In this phase 2b study, all-oral regimens of antiviral agents and ribavirin were effective both in patients with HCV genotype 1 infection who had not received therapy previously and in those who had not had a response to prior therapy. (Funded by AbbVie; ClinicalTrials.gov number, NCT01464827.).

Discovery of ABT-267, a pan-genotypic inhibitor of HCV NS5A

We describe here N-phenylpyrrolidine-based inhibitors of HCV NS5A with excellent potency, metabolic stability, and pharmacokinetics. Compounds with 2S,5S stereochemistry at the pyrrolidine ring provided improved genotype 1 (GT1) potency compared to the 2R,5R analogues. Furthermore, the attachment of substituents at the 4-position of the central N-phenyl group resulted in compounds with improved potency. Substitution with tert-butyl, as in compound 38 (ABT-267), provided compounds with low-picomolar EC50 values and superior pharmacokinetics. It was discovered that compound 38 was a pan-genotypic HCV inhibitor, with an EC50 range of 1.7-19.3 pM against GT1a, -1b, -2a, -2b, -3a, -4a, and -5a and 366 pM against GT6a. Compound 38 decreased HCV RNA up to 3.10 log10 IU/mL during 3-day monotherapy in treatment-naive HCV GT1-infected subjects and is currently in phase 3 clinical trials in combination with an NS3 protease inhibitor with ritonavir (r) (ABT-450/r) and an NS5B non-nucleoside polymerase inhibitor (ABT-333), with and without ribavirin.

A phase 2a trial of 12-week interferon-free therapy with two direct-acting antivirals (ABT-450/r, ABT-072) and ribavirin in IL28B C/C patients with chronic hepatitis C genotype 1

BACKGROUND & AIMS

ABT-450 (combined with low-dose ritonavir, ABT-450/r) is a potent HCV NS3 protease inhibitor, and ABT-072 is a non-nucleoside NS5B polymerase inhibitor. The goal of this study was to evaluate the safety, tolerability, and efficacy of the peginterferon-free combination of ABT-450/r and ABT-072 with ribavirin in treatment-naïve patients with IL28B CC genotype, infected with HCV genotype 1.

METHODS

This was a phase 2a, multicenter, open-label, single-arm study in 11 treatment-naïve, non-cirrhotic HCV GT1-infected patients with IL28B rs12979860 genotype CC. Patients received ABT-450/r 150/100 mg once daily and ABT-072 400 mg once daily with weight-based ribavirin 1000-1200 mg/day dosed twice daily for 12 weeks.

RESULTS

Eight (73%) patients were male, 9 (82%) were Caucasian (including 3 who self-identified as Hispanic); mean baseline HCV RNA was 6.9 log₁₀ IU/ml (range 6.5-7.3 log₁₀ IU/ml). All 11 patients completed 12 weeks of treatment and maintained HCV RNA <25 IU/ml from weeks 4 through 12 of treatment. Ten patients (91%) achieved sustained virologic response 24 weeks post-treatment, with a second patient relapsing 36 weeks post-treatment. There were no deaths, serious or severe adverse events, or premature discontinuations. Adverse events were mostly mild and the most frequent were headache, fatigue, nausea, and dry skin.

CONCLUSIONS

A 12-week regimen of ABT-450/r and ABT-072 with ribavirin was well tolerated with 9/11 patients achieving sustained virologic response through 36 weeks of post-treatment observation. These findings suggest that peginterferon-free regimens may have the potential to cure a high proportion of HCV genotype 1-infected patients.

High potency improvements to weak aryl uracil HCV polymerase inhibitor leads

Described herein is the development of a potent non-nucleoside, small molecule inhibitor of genotype 1 HCV NS5B Polymerase. A 23 μM inhibitor that was active against HCV polymerase was further elaborated into a potent single-digit nanomolar inhibitor of HCV NS5B polymerase by additional manipulation of the R and R1 substituents. Subsequent modifications to improve physical properties were made in an attempt to achieve an acceptable pharmacokinetic profile.

Exploratory study of oral combination antiviral therapy for hepatitis C

BACKGROUND

There is a need for interferon-free treatment regimens for hepatitis C virus (HCV) infection. The goal of this study was to evaluate ABT-450, a potent HCV NS3 protease inhibitor, combined with low-dose ritonavir (ABT-450/r), in addition to ABT-333, a nonnucleoside NS5B polymerase inhibitor, and ribavirin, for the treatment of HCV infection.

METHODS

We conducted a 12-week, phase 2a, open-label study involving patients who had HCV genotype 1 infection without cirrhosis. All patients received ABT-333 (400 mg twice daily) and ribavirin (1000 to 1200 mg per day) and one of two daily doses of ABT-450/r. Groups 1 and 2 included previously untreated patients; group 1 received 250 mg of ABT-450 and 100 mg of ritonavir, and group 2 received 150 mg and 100 mg, respectively. Group 3, which included patients who had had a null or partial response to previous therapy with peginterferon and ribavirin, received daily doses of 150 mg of ABT-450 and 100 mg of ritonavir. The primary end point was an undetectable level of HCV RNA from week 4 through week 12 (extended rapid virologic response).

RESULTS

A total of 17 of the 19 patients in group 1 (89%) and 11 of the 14 in group 2 (79%) had an extended rapid virologic response; a sustained virologic response 12 weeks after the end of treatment was achieved in 95% and 93% of the patients, respectively. In group 3, 10 of 17 patients (59%) had an extended rapid virologic response, and 8 (47%) had a sustained virologic response 12 weeks after therapy; 6 patients had virologic breakthrough, and 3 had a relapse. Adverse events included abnormalities in liver-function tests, fatigue, nausea, headache, dizziness, insomnia, pruritus, rash, and vomiting.

CONCLUSIONS

This preliminary study suggests that 12 weeks of therapy with a combination of a protease inhibitor, a nonnucleoside polymerase inhibitor, and ribavirin may be effective for treatment of HCV genotype 1 infection. (Funded by Abbott; ClinicalTrials.gov number, NCT01306617.).

Appearance of a single amino acid insertion at position 33 in HIV type 1 protease under a lopinavir-containing regimen, associated with reduced protease inhibitor susceptibility

HIV drug resistance is a multifactorial phenomenon and constitutes a major concern as it results in therapy failure. The aim of this study was to assess the impact of an amino acid insertion identified at position 33 of the protease gene, derived from samples from three patients under lopinavir therapy, on viral fitness and protease inhibitor (PI) resistance. Successive samples were available from one of the patients for genotypic and phenotypic testing in order to investigate the role of this insertion. The patient had been pretreated with various antiretroviral drugs and showed poor virological response from the point of the acquisition of the mutation onward. The insertion was acquired in the context of a number of other PI mutations and was stable following acquisition. Phenotypic testing revealed reduced susceptibility to various PIs and a reduction of the replicative capacity (RC) of the virus. In the presence of the insertion alone, a decrease of the RC was observed, which seemed to be compensated by the presence of other mutations. The L33ins might have a potential role in PI resistance pathways but further investigation in a larger number of clinical samples is required in order to elucidate this resistance mechanism.

Development of a cell-based assay for high-throughput screening of inhibitors against HCV genotypes 1a and 1b in a single well

The Hepatitis C (HCV) replicon system is a useful tool for the high-volume screening of inhibitors of HCV replication. In this report, a cell-based assay has been described, which monitors the inhibition of HCV genotypes 1a and 1b as well as cytotoxicity, from a single well of a 96-well plate. A mixture of two stable replicon cell lines was used: one containing a 1a-H77 replicon expressing a firefly luciferase reporter, and the other one containing a 1b-N replicon with a secreted alkaline phosphatase reporter, thus allowing us to monitor replication of two HCV genotypes in the same well. Cytotoxicity was measured using the Resazurin cytotoxicity assay. The assay was validated with known HCV inhibitors and showed that the antiviral activity and cytotoxicity of compounds were reproducibly measured under screening conditions. It was also showed that the assay's signal-to-noise ratio and Z' coefficient were suitable for high-throughput screening. A panel of HCV inhibitors showed a good correlation between EC(50) and TD(50) values for 1a and 1b replicon activity and cytotoxicity measured using either a single replicon format or mixed replicon format. Thus, the use of this mixed replicon format provides an economical method for simultaneous measurement of compound activity against two HCV genotypes as well as cytotoxicity, thereby reducing cost of reagents and labor as well as improving throughput.

A replicon-based shuttle vector system for assessing the phenotype of HCV NS5B polymerase genes isolated from patient populations

Hepatitis C virus (HCV) replicon-based shuttle vectors that permit phenotypes of NS5B polymerase genes from a large number of patient isolates to be rapidly assessed when transiently expressed in cultured cells were designed. When used to test responses to an inhibitor of HCV RNA-dependent RNA polymerase, IC(50) values for inhibition covered a several hundred-fold range among 47 patient samples tested. This observation highlights the variability that can be found by testing isolates derived from HCV-infected subjects. Partial suppression with a polymerase inhibitor of the most sensitive species permitted detection of minor quasispecies that were 7-200-fold more resistant than the bulk population in approximately half of the samples. Sequence analysis showed a wide range of amino acid changes not detected by conventional selection methods using laboratory-derived strains. This approach provides a means to assess variation in antiviral efficacy, and to predict possible responses in a clinical setting.

Identification of host genes involved in hepatitis C virus replication by small interfering RNA technology

Hepatitis C virus (HCV) replication is highly dependent on host cell factors. Identification of these host factors not only facilitates understanding of the biology of HCV infection but also enables the discovery of novel targets for anti-HCV therapy. To identify host genes important for HCV RNA replication, we screened a library of small interfering RNA (siRNA) that targets approximately 4,000 human genes in Huh7-derived EN5-3 cells harboring an HCV subgenomic replicon with the nonstructural region NS3-NS5B from the 1b-N strain. Nine cellular genes that potentially regulate HCV replication were identified in this screen. Silencing of these genes resulted in inhibition of HCV replication by more than 60% and exhibited minimal toxicity. Knockdown of host gene expression by these siRNAs was confirmed at the RNA level and, in some instances, at the protein level. The level of siRNA silencing of these host genes correlated well with inhibition of HCV. These genes included those that encoded a G-protein coupled receptor (TBXA2R), a membrane protein (LTbeta), an adapter protein (TRAF2), 2 transcription factors (RelA and NFkappaB2), 2 protein kinases (MKK7 and SNARK), and 2 closely related transporter proteins (SLC12A4 and SLC12A5). Of interest, some of these genes are members of the tumor necrosis factor/lymphotoxin signaling pathway.

CONCLUSION

Findings of this study may provide important information for understanding HCV replication. In addition, these cellular genes may constitute a novel set of targets for HCV antiviral therapy.

Identification and characterization of mutations conferring resistance to an HCV RNA-dependent RNA polymerase inhibitor in vitro

Compound A-837093, a non-nucleoside HCV RNA-dependent RNA polymerase inhibitor, displayed nanomolar potencies against HCV genotypes 1a and 1b replicons. It also exhibited an excellent metabolic profile and achieved high plasma and liver concentrations in animals. In order to characterize the development of resistance to this anti-HCV agent, HCV subgenomic 1b strain N replicon cells were cultured in the presence of A-837093 with G418. Mutations S368A, Y448H, G554D, Y555C, and D559G in the NS5B polymerase gene were identified that led to substantial decreases in the susceptibilities of 1b genotype replicons to the inhibitor A-837093. However, the resistant mutants remained susceptible to HCV protease inhibitor BILN-2061 and alpha interferon as well as to a different class of non-nucleoside HCV polymerase inhibitor. In addition, each single resistant mutation identified significantly reduced the replication capacity of mutant compared to wild-type replicon. These findings provide a strategic guide for the future development of non-nucleoside inhibitors of HCV NS5B polymerase.

Replication efficiency of chimeric replicon containing NS5A-5B genes derived from HCV-infected patient sera

A transient subgenomic replicon-based shuttle vector system has been developed to investigate how genetic heterogeneity affects HCV replication efficiency. Individual NS5A or NS5B genes or cassettes containing both NS5A and NS5B genes were amplified from "quasispecies" pools derived from HCV genotype 1a or 1b patient sera using RT-PCR and cloned into their respective shuttle vectors. All shuttle vectors containing NS5A or NS5A-5B genes were constructed with the S2204I "adaptive" mutation because replicons lacking the S2204I mutation replicated poorly. Gene sequences of the quasispecies pools within either genotype 1a or 1b patient samples ranged from 94 to 95% in identity. The replication capacity of 1b shuttle vectors containing patient-derived NS5A or NS5B genes averaged 67 and 75%, respectively, relative to the laboratory-optimized 1b replicon. In contrast, the replication efficiencies of both 1a and 1b shuttle vectors containing patient-derived NS5A-5B gene cassettes averaged around 2% relative to the respective laboratory-optimized replicon. All patient-derived replicons were tested in a transient assay for their sensitivity to either interferon-alpha (IFN-alpha) or to the polymerase inhibitor A-782759. Despite the differences in replication efficiency, IC(50) values measured for most of the patient-derived replicons were equivalent to the respective values measured in the control laboratory strain replicons. These results demonstrate that patient sequence heterogeneity affects replication efficiency whenever patient-derived NS5A-5B genes are inserted into the laboratory-optimized replicon. The findings also demonstrate the utility of the shuttle vector system to test patient-derived gene sequences for sensitivity to IFN-alpha and to small molecule inhibitors.

Mutations conferring resistance to a hepatitis C virus (HCV) RNA-dependent RNA polymerase inhibitor alone or in combination with an HCV serine protease inhibitor in vitro

Compounds A-782759 (an N-1-aza-4-hydroxyquinolone benzothiadiazine) and BILN-2061 are specific anti-hepatitis C virus (HCV) agents that inhibit the RNA-dependent RNA polymerase and the NS3 serine protease, respectively. Both compounds display potent activity against HCV replicons in tissue culture. In order to characterize the development of resistance to these anti-HCV agents, HCV subgenomic 1b-N replicon cells were cultured with A-782759 alone or in combination with BILN-2061 at concentrations 10 times above their corresponding 50% inhibitory concentrations in the presence of neomycin. Single substitutions in the NS5B polymerase gene (H95Q, N411S, M414L, M414T, or Y448H) resulted in substantial decreases in susceptibility to A-782759. Similarly, replicons containing mutations in the NS5B polymerase gene (M414L or M414T), together with single mutations in the NS3 protease gene (A156V or D168V), conferred high levels of resistance to both A-782759 and BILN-2061. However, the A-782759-resistant mutants remained susceptible to nucleoside and two other classes of nonnucleoside NS5B polymerase inhibitors, as well as interferon. In addition, we found that the frequency of replicons resistant to both compounds was significantly lower than the frequency of resistance to the single compound. Furthermore, the dually resistant mutants displayed significantly reduced replication capacities compared to the wild-type replicon. These findings provide strategic guidance for the future treatment of HCV infection.

Determination of hepatitis E virus seroprevalence by using recombinant fusion proteins and synthetic peptides

Recombinant antigens from hepatitis E virus (HEV) open-reading frames 2 and 3 were expressed in Escherichia coli as cytidine monophosphate-2-keto-3-deoxyoctulosonic acid synthetase (CKS) fusion proteins, purified, and used to develop an EIA for the detection of antibodies. Serologic results were compared with those of previous assays by testing 102 samples from an HEV outbreak in Somalia. This CKS/HEV EIA detected anti-HEV in all 97 sera found reactive previously and in an additional 2 samples, which were shown to be true HEV-positive samples by supplemental peptide and Western blot tests. The CKS/HEV EIA and supplemental assays were then used to determine seroprevalence of HEV worldwide. HEV seroprevalence ranged from 1% to 25%, with higher rates found in Middle Eastern countries. Also, 7%-14% of acute cases of non-A, -B, or -C hepatitis were HEV-positive. Thus, this CKS/HEV EIA appears useful for detecting anti-HEV in various populations.

cDNA, deduced polypeptide structure and chromosomal assignment of human pulmonary surfactant proteolipid, SPL(pVal)

In hyaline membrane disease of premature infants, lack of surfactant leads to pulmonary atelectasis and respiratory distress. Hydrophobic surfactant proteins of Mr = 5,000-14,000 have been isolated from mammalian surfactants which enhance the rate of spreading and the surface tension lowering properties of phospholipids during dynamic compression. We have characterized the amino-terminal amino acid sequence of pulmonary proteolipids from ether/ethanol extracts of bovine, canine, and human surfactant. Two distinct peptides were identified and termed SPL(pVal) and SPL(Phe). An oligonucleotide probe based on the valine-rich amino-terminal amino acid sequence of SPL(pVal) was utilized to isolate cDNA and genomic DNA encoding the human protein, termed surfactant proteolipid SPL(pVal) on the basis of its unique polyvaline domain. The primary structure of a precursor protein of 20,870 daltons, containing the SPL(pVal) peptide, was deduced from the nucleotide sequence of the cDNAs. Hybrid-arrested translation and immunoprecipitation of labeled translation products of human mRNA demonstrated an Mr = 22,000 precursor protein, the active hydrophobic peptide being produced by proteolytic processing to Mr = 5,000-6,000. Two classes of cDNAs encoding SPL(pVal) were identified. mRNA of approximately 900 bases was identified on Northern analysis of fetal and adult RNA. Human SPL(pVal) mRNA was more abundant in the adult than in fetal lung. The SPL(pVal) gene locus was assigned to chromosome 8.

cDNA and deduced amino acid sequence of human pulmonary surfactant-associated proteolipid SPL(Phe)

Hydrophobic surfactant-associated protein of Mr 6000-14,000 was isolated from ether/ethanol or chloroform/methanol extracts of mammalian pulmonary surfactant. Automated Edman degradation in a gas-phase sequencer showed the major N-terminus of the human low molecular weight protein to be Phe-Pro-Ile-Pro-Leu-Pro-Tyr-Cys-Trp-Leu-Cys-Arg-Ala-Leu-. Because of the N-terminal phenylalanine, the surfactant protein was designated SPL(Phe). Antiserum generated against hydrophobic surfactant protein(s) from bovine pulmonary surfactant recognized protein of Mr 6000-14,000 in immunoblot analysis and was used to screen a lambda gt11 expression library constructed from adult human lung poly(A)+ RNA. This resulted in identification of a 1.4-kilobase cDNA clone that was shown to encode the N-terminus of the surfactant polypeptide SPL(Phe) (Phe-Pro-Ile-Pro-Leu-Pro-) within an open reading frame for a larger protein. Expression of a fused beta-galactosidase-SPL(Phe) gene in Escherichia coli yielded an immunoreactive Mr 34,000 fusion peptide. Hybrid-arrested translation with this cDNA and immunoprecipitation of [35S]methionine-labeled in vitro translation products of human poly(A)+ RNA with a surfactant polyclonal antibody resulted in identification of a Mr 40,000 precursor protein. Blot hybridization analysis of electrophoretically fractionated RNA from human lung detected a 2.0-kilobase RNA that was more abundant in adult lung than in fetal lung. The larger RNA and translation product indicates that SPL(Phe) is derived by proteolysis of a large polypeptide precursor. The amino acid sequence of the predicted protein, beginning Phe-Pro-Ile-Pro-Leu-Pro-Try-, comprises a hydrophobic peptide that is a major protein component of surfactant lipid extracts used successfully to treat hyaline membrane disease in newborn infants. These proteins, and specifically SPL(Phe), may therefore be useful for synthesis of replacement surfactants for treatment of hyaline membrane disease in newborn infants or of other surfactant-deficient states.