Gerhard Steinmann

An NS3 protease inhibitor with antiviral effects in humans infected with hepatitis C virus

Hepatitis C virus (HCV) infection is a serious cause of chronic liver disease worldwide with more than 170 million infected individuals at risk of developing significant morbidity and mortality. Current interferon-based therapies are suboptimal especially in patients infected with HCV genotype 1, and they are poorly tolerated, highlighting the unmet medical need for new therapeutics. The HCV-encoded NS3 protease is essential for viral replication and has long been considered an attractive target for therapeutic intervention in HCV-infected patients. Here we identify a class of specific and potent NS3 protease inhibitors and report the evaluation of BILN 2061, a small molecule inhibitor biologically available through oral ingestion and the first of its class in human trials. Administration of BILN 2061 to patients infected with HCV genotype 1 for 2 days resulted in an impressive reduction of HCV RNA plasma levels, and established proof-of-concept in humans for an HCV NS3 protease inhibitor. Our results further illustrate the potential of the viral-enzyme-targeted drug discovery approach for the development of new HCV therapeutics.

Antiviral efficacy of NS3‐serine protease inhibitor BILN‐2061 in patients with chronic genotype 2 and 3 hepatitis C

BILN‐2061, a specific and potent peptidomimetic inhibitor of the HCV NS3 protease, has recently been shown to markedly lower serum hepatitis C virus (HCV)‐RNA levels in patients chronically infected with HCV genotype 1 in three 2‐day proof of principle studies. The aim of the current study was to assess the antiviral efficacy of BILN‐2061 in patients with genotypes 2 and 3 HCV infection. The antiviral efficacy, pharmacokinetics, and tolerability of 500 mg twice‐daily BILN‐2061 given as monotherapy for 2 days in 10 patients chronically infected with non–genotype 1 HCV (genotype 2: n = 3; genotype 3: n =7) and minimal liver fibrosis (Ishak score 0‐2) were assessed in a placebo‐controlled (placebo n = 2), double‐blind pilot study. HCV‐RNA levels decreased by ≥1 log10 copies/mL in 4 of 8 patients treated with BILN‐2061. One patient showed a weak response of <1 log10 copies/mL. Three of 8 treated patients showed no response. There was no correlation between baseline viral concentration or genotype and response. BILN‐2061 exhibited good systemic exposure after oral administration and was well tolerated. In conclusion, the antiviral efficacy of the HCV serine protease inhibitor BILN‐2061 is less pronounced and more variable in patients with HCV genotype 2 or 3 infection compared with previous results in patients with HCV genotype 1. A lower affinity of BILN‐2061 for the NS3 protease of genotypes 2 and 3 HCV is most likely a major contributor to these findings. (HEPATOLOGY 2005.)

Potency, safety, and pharmacokinetics of the NS3/4A protease inhibitor BI201335 in patients with chronic HCV genotype-1 infection

BACKGROUND & AIMS BI201335 is a highly specific and potent HCV protease inhibitor. This multiple rising dose trial evaluated antiviral activity and safety in chronic HCV genotype-1 patients. METHODS Thirty-four treatment-naïve patients were randomized to monotherapy with placebo or BI201335 at 20-240 mg once-daily for 14 days, followed by combination with pegylated interferon alfa/ribavirin (PegIFN/RBV) through Day 28. Nineteen treatment-experienced patients received 48-240 mg BI201335 once-daily with PegIFN/RBV for 28 days. HCV-RNA was measured with Roche COBAS TaqMan. RESULTS In treatment-naïve patients, median maximal viral load (VL) reductions during 14-day monotherapy were -3.0, -3.6, -3.7, and -4.2 log(10) for the 20, 48, 120, and 240 mg groups. VL breakthroughs (≥1 log(10) from nadir) were seen in most patients on monotherapy and were caused by NS3/4A variants (R155K, D168V) conferring in vitro resistance to BI201335. Adding PegIFN/RBV at Days 15-28 led to continuous viral load reductions in most patients. In treatment-experienced patients, treatment with BI201335 and PegIFN/RBV achieved VL<25 IU/ml at Day 28 in 3/6, 4/7, and 5/6 patients in the 48, 120, and 240 mg dose groups. VL breakthroughs were observed during triple combination in only 3/19 patients. BI201335 was generally well tolerated. Mild rash or photosensitivity was detected in four patients. Mild unconjugated hyperbilirubinemia was the only dose-dependent laboratory abnormality of BI201335. BI201335 elimination half-life supports once-daily dosing. CONCLUSIONS BI201335 combined with PegIFN/RBV was well tolerated and induced strong antiviral responses. These results support further development of BI201335 in HCV genotype-1 patients.

Faldaprevir combined with pegylated interferon alfa-2a and ribavirin in treatment-naïve patients with chronic genotype1 HCV: SILEN-C1 trial†‡

Faldaprevir (BI 201335) is a potent, hepatitis C virus (HCV) NS3/4A protease inhibitor with pharmacokinetic properties supportive of once‐daily (QD) dosing. Four hundred and twenty‐nine HCV genotype (GT)‐1 treatment‐naïve patients without cirrhosis were randomized 1:1:2:2 to receive 24 weeks of pegylated interferon alfa‐2a and ribavirin (PegIFN/RBV) in combination with placebo, faldaprevir 120 mg QD with 3 days of PegIFN/RBV lead‐in (LI), 240 mg QD with LI, or 240 mg QD without LI, followed by an additional 24 weeks of PegIFN/RBV. Patients in the 240 mg QD groups achieving maintained rapid virologic response (mRVR; viral load [VL] <25 IU/mL at week 4 and undetectable at weeks 8‐20) were rerandomized to cease all treatment at week 24 or continue receiving PegIFN/RBV up to week 48. VL was measured by Roche TaqMan. Sustained virologic response (SVR) rates were 56%, 72%, 72%, and 84% in the placebo, faldaprevir 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD groups. Ninety‐two percent of mRVR patients treated with faldaprevir 240 mg QD achieved SVR, irrespective of PegIFN/RBV treatment duration. Eighty‐two percent of GT‐1a patients who received faldaprevir 240 mg QD achieved SVR versus 47% with placebo. Mild gastrointestinal disorders, jaundice resulting from isolated unconjugated hyperbilirubinemia, and rash or photosensitivity were more common in the active groups than with placebo. Discontinuations resulting from adverse events occurred in 4%, 11%, and 5% of patients treated with 120 mg QD/LI, 240 mg QD/LI, and 240 mg QD of faldaprevir versus 1% with placebo. Conclusion: Faldaprevir QD with PegIFN/RBV achieved consistently high SVR rates with acceptable tolerability and safety at all dose levels. The 120 and 240 mg QD doses are currently undergoing phase 3 evaluation. (HEPATOLOGY 2013;57:2143–2154)

Baseline Hepatitis C Virus (HCV) NS3 Polymorphisms and Their Impact on Treatment Response in Clinical Studies of the HCV NS3 Protease Inhibitor Faldaprevir

ABSTRACT A challenge to the treatment of chronic hepatitis C with direct-acting antivirals is the emergence of drug-resistant hepatitis C virus (HCV) variants. HCV with preexisting polymorphisms that are associated with resistance to NS3/4A protease inhibitors have been detected in patients with chronic hepatitis C. We performed a comprehensive pooled analysis from phase 1b and phase 2 clinical studies of the HCV protease inhibitor faldaprevir to assess the population frequency of baseline protease inhibitor resistance-associated NS3 polymorphisms and their impact on response to faldaprevir treatment. A total of 980 baseline NS3 sequences were obtained (543 genotype 1b and 437 genotype 1a sequences). Substitutions associated with faldaprevir resistance (at amino acid positions 155 and 168) were rare (<1% of sequences) and did not compromise treatment response: in a phase 2 study in treatment-naive patients, six patients had faldaprevir resistance-associated polymorphisms at baseline, of whom five completed faldaprevir-based treatment and all five achieved a sustained virologic response 24 weeks after the end of treatment (SVR24). Among 13 clinically relevant amino acid positions associated with HCV protease resistance, the greatest heterogeneity was seen at NS3 codons 132 and 170 in genotype 1b, and the most common baseline substitution in genotype 1a was Q80K (99/437 [23%]). The presence of the Q80K variant did not reduce response rates to faldaprevir-based treatment. Across the three phase 2 studies, there was no significant difference in SVR24 rates between patients with genotype 1a Q80K HCV and those without Q80K HCV, whether treatment experienced (17% compared to 26%; P = 0.47) or treatment naive (62% compared to 66%; P = 0.72).

66 SILEN-C2: SUSTAINED VIROLOGIC RESPONSE (SVR) AND SAFETY OF BI201335 COMBINED WITH PEGINTERFERON ALFA-2A AND RIBAVIRIN (P/R) IN CHRONIC HCV GENOTYPE-1 PATIENTS WITH NON-RESPONSE TO P/R

66 SILEN-C2: SUSTAINED VIROLOGIC RESPONSE (SVR) AND SAFETY OF BI201335 COMBINED WITH PEGINTERFERON ALFA-2A AND RIBAVIRIN (P/R) IN CHRONIC HCV GENOTYPE-1 PATIENTS WITH NON-RESPONSE TO P/R M.S. Sulkowski, M. Bourliere, J.-P. Bronowicki, A. Streinu-Cercel, L. Preotescu, T. Asselah, J.-M. Pawlotsky, S. Shafran, S. Pol, F.A. Caruntu, S. Mauss, D. Larrey, C. Hafner, Y. Datsenko, J.O. Stern, R. Kubiak, W. Bocher, G. Steinmann. Johns Hopkins University, Baltimore, MD, USA; Hopital Saint Joseph, Marseille, Hopital de Brabois, Vandoeuvre Cedex, France; “Prof. Dr. Matei Bals” Institute of Infectious Diseases, Bucharest, Romania; Hopital Beaujon, Clichy Cedex, Hopital Henri Mondor, Creteil, France; University of Alberta, Edmonton, AB, Canada; Hopital Cochin, Paris, France; Center for HIV and Hepatogastroenterology, Dusseldorf, Germany; Hopital Saint-Eloi, Montpellier Cedex, France; Boehringer Ingelheim Pharma, Biberach, Germany; Boehringer Ingelheim Pharmaceuticals, Ridgefield, CT, USA E-mail: msulkowski@jhmi.edu

Mechanisms Underlying Benign and Reversible Unconjugated Hyperbilirubinemia Observed with Faldaprevir Administration in Hepatitis C Virus Patients

Faldaprevir, an investigational agent for hepatitis C virus treatment, is well tolerated but associated with rapidly reversible, dose-dependent, clinically benign, unconjugated hyperbilirubinemia. Multidisciplinary preclinical and clinical studies were used to characterize mechanisms underlying this hyperbilirubinemia. In vitro, faldaprevir inhibited key processes involved in bilirubin clearance: UDP glucuronosyltransferase (UGT) 1A1 (UGT1A1) (IC50 0.45 µM), which conjugates bilirubin, and hepatic uptake and efflux transporters, organic anion–transporting polypeptide (OATP) 1B1 (IC50 0.57 µM), OATP1B3 (IC50 0.18 µM), and multidrug resistance–associated protein (MRP) 2 (IC50 6.2 µM), which transport bilirubin and its conjugates. In rat and human hepatocytes, uptake and biliary excretion of [3H]bilirubin and/or its glucuronides decreased on coincubation with faldaprevir. In monkeys, faldaprevir (≥20 mg/kg per day) caused reversible unconjugated hyperbilirubinemia, without hemolysis or hepatotoxicity. In clinical studies, faldaprevir-mediated hyperbilirubinemia was predominantly unconjugated, and levels of unconjugated bilirubin correlated with the UGT1A1*28 genotype. The reversible and dose-dependent nature of the clinical hyperbilirubinemia was consistent with competitive inhibition of bilirubin clearance by faldaprevir, and was not associated with liver toxicity or other adverse events. Overall, the reversible, unconjugated hyperbilirubinemia associated with faldaprevir may predominantly result from inhibition of bilirubin conjugation by UGT1A1, with inhibition of hepatic uptake of bilirubin also potentially playing a role. Since OATP1B1/1B3 are known to be involved in hepatic uptake of circulating bilirubin glucuronides, inhibition of OATP1B1/1B3 and MRP2 may underlie isolated increases in conjugated bilirubin. As such, faldaprevir-mediated hyperbilirubinemia is not associated with any liver injury or toxicity, and is considered to result from decreased bilirubin elimination due to a drug-bilirubin interaction.

Safety and efficacy of faldaprevir with pegylated interferon alfa-2a and ribavirin in Japanese patients with chronic genotype-1 hepatitis C infection

Faldaprevir (BI 201335) is a potent once‐daily (QD) NS3/4A protease inhibitor for the treatment of patients with genotype‐1 (GT‐1) hepatitis C virus (HCV). The aim of this study was to evaluate the safety, pharmacokinetics and efficacy of faldaprevir plus pegylated interferon alfa‐2a (PegIFN) and ribavirin (RBV) in Japanese patients infected with chronic GT‐1 HCV.

SILEN-C3, a Phase 2 Randomized Trial with Faldaprevir plus Pegylated Interferon α-2a and Ribavirin in Treatment-Naive Hepatitis C Virus Genotype 1-Infected Patients

ABSTRACT Faldaprevir is an investigational hepatitis C virus (HCV) NS3/4A protease inhibitor which, when administered for 24 weeks in combination with pegylated interferon α-2a and ribavirin (PegIFN/RBV) in treatment-naive patients in a prior study (SILEN-C1; M. S. Sulkowski et al., Hepatology 57:2143–2154, 2013, doi:10.1002/hep.26276), achieved sustained virologic response (SVR) rates of 72 to 84%. The current randomized, open-label, parallel-group study compared the efficacy and safety of 12 versus 24 weeks of 120 mg faldaprevir administered once daily, combined with 24 or 48 weeks of PegIFN/RBV, in 160 treatment-naive HCV genotype 1 patients. Patients with maintained rapid virologic response (HCV RNA of <25 IU/ml at week 4 and undetectable at weeks 8 and 12) stopped all treatment at week 24, otherwise they continued PegIFN/RBV to week 48. SVR was achieved by 67% and 74% of patients in the 12-week and 24-week groups, respectively. Virologic response rates were lower in the 12-week group from weeks 2 to 12, during which both groups received identical treatment. SVR rates were similar in both groups for patients achieving undetectable HCV RNA. Most adverse events were mild or moderate, and 6% of patients in each treatment group discontinued treatment due to adverse events. Once-daily faldaprevir at 120 mg for 12 or 24 weeks with PegIFN/RBV resulted in high SVR rates, and the regimen was well tolerated. Differences in the overall SVR rates between the 12-week and 24-week groups were not statistically significant and possibly were due to IL28B genotype imbalances; IL28B genotype was not tested, as its significance was not known at the time of the study. These results supported phase 3 evaluation. (This study has been registered at ClinicalTrials.gov under registration no. NCT00984620).

Clinical Experiences with lnterferon-α and Interferon-γ

Publisher Summary This chapter discusses the classification, pharmacology, clinical efficacy, and clinical toxicity of interferon (IF)- α and γ . Interferons can be subdivided into two classes according to their acid stability. The first class, which is acid-proof, consists of three families, namely, α , β , and ω . The second class consists of interferon- γ , which is not acid-proof interferon- γ , is predominantly produced by leukocytes, B cells, T cells, null cells, and macrophages following exposure to B cell mitogens, viruses, foreign cells, or tumor cells. Interferon- β is predominantly produced by fibroblasts following exposure to viruses or foreign nucleic acids. Interferon- ω is produced by lymphocytes after exposure to viruses, and interferon- γ is produced by T lymphocytes following stimulation with T cell mitogens, specific antigens, or interleukin-2. The use of interferon- α in the treatment of malignant hematological diseases and solid tumors is now well established in clinical practice. Adverse effects of interferon- α can be major obstacles to its clinical use. Particularly in early trials, the high dosage levels were associated with severe clinical toxicities in a typical pattern of early and late adverse effects. Several phase I studies and open studies with interferon- α -2c in patients suffering from advanced malignancies have identified a maximum tolerated dose of 32.5 × 10 6 U/day i.m.