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.

Development and validation of a high-throughput screening assay for the hepatitis C virus p7 viroporin.

The HCV p7 protein is not involved in viral RNA replication but is essential for production of infectious virus. Based on its putative ion channel activity, p7 belongs to a family of viral proteins known as viroporins that oligomerize after insertion into a lipid membrane. To screen for compounds capable of interfering with p7 channel function, a low-throughput liposome-based fluorescent dye permeability assay was modified and converted to a robust high-throughput screening assay. Escherichia coli expressing recombinant p7 were grown in high-density fed-batch fermentation followed by a detergent-free purification using a combination of affinity and reversed-phase chromatography. The phospholipid composition of the liposomes was optimized for both p7 recognition and long-term stability. A counterscreen was developed using the melittin channel-forming peptide to eliminate nonspecific screening hits. The p7 liposome-based assay displayed robust statistics (Z' > 0.75), and sensitivity to inhibition was confirmed using known inhibitors.