Interferon-Free Treatments for Chronic Hepatitis C Genotype 1 Infection

Simeprevir, daclatasvir, and sofosbuvir for hepatitis C virus-infected patients: Long-term follow-up results from the open-label, Phase II IMPACT study

BACKGROUND AND AIMS

Direct-acting antiviral agents (DAAs) for hepatitis C virus (HCV) infection have resulted in high rates of sustained virologic response (SVR) following 8 to 24 weeks of treatment. However, difficult-to-cure/cirrhotic patients typically require a longer treatment duration and less is known regarding the long-term durability of SVR or effect on liver disease progression; to assess this, the IMPACT study followed patients for a 3-year period after end of treatment.

METHODS

The Phase II, open-label, nonrandomized IMPACT study assessed the efficacy, safety, and pharmacokinetics of the combination of three DAAs (simeprevir, sofosbuvir, and daclatasvir) in HCV genotype 1/4-infected, treatment-naïve/-experienced cirrhotic patients with portal hypertension or decompensated liver disease. Patients from a single site in the United States were assigned to one of two groups by Child-Pugh (CP) score: CP A, CP score less than 7 and evidence of portal hypertension; CP B, CP score of 7 to 9. All patients received simeprevir 150 mg, daclatasvir 60 mg, and sofosbuvir 400 mg once-daily for 12 weeks between September 2014 and August 2015. All 40 patients included in the study (male, 63%; median age, 58.5 years) achieved SVR 12 and 24 weeks after end of treatment, and the combination was well tolerated.

RESULTS

All patients who reached the 3-year follow-up timepoint maintained SVR (CP A, 15/15; CP B, 18/18). CP scores and Model for End-stage Liver Disease scores remained relatively stable, and mean FibroScan and FibroTest scores declined. No new safety signals were identified.

CONCLUSIONS

In the IMPACT study, virologic response to simeprevir, sofosbuvir, and daclatasvir was durable over 3 years (http://ClinicalTrials.gov number: NCT02262728).

Manipulation of both virus- and cell-specific factors is required for robust transient replication of a hepatitis C virus genotype 3a sub-genomic replicon

Hepatitis C virus (HCV) genotype (GT) 3 is the second most prevalent of the seven HCV genotypes and exhibits the greatest resistance to the highly potent, direct-acting antivirals (DAAs) that are currently in use. Previously a stable cell line harbouring the S52 GT3 sub-genomic replicon (SGR) was established, but this SGR was unable to robustly replicate transiently. As transient SGRs are a critical tool in the development of DAAs, and in the study of viral resistance, we sought to establish a transient SGR system based on S52. Next-generation sequencing was used to identify putative culture-adaptive substitutions that had arisen during long-term selection of the S52 SGR. A subset of these substitutions was built back into the S52 SGR in the context of a CpG/UpA-low luciferase reporter, with a single point mutation in NS4A conferring the greatest replication capability upon S52. Modification of the innate immune-sensing pathways of Huh7.5 hepatoma cells by expression of the parainfluenza virus type 5 V protein and SEC14L2 resulted in a further enhancement of S52 replication. Furthermore, this transiently replicating SGR showed genotype-specific differences in sensitivity to two clinically relevant NS5A DAAs. In conclusion, we report that a single substitution in NS4A, coupled with host cell modifications, enabled robust levels of transient replication by the GT3 S52 SGR. This system will have beneficial uses in both basic research into the unique aspects of GT3 biology and drug discovery.