Faculty Bibliography

The US Food and Drug Administration has now approved 10 direct-acting antivirals (DAAs) for the management of hepatitis C virus (HCV). These therapies are combined into 6 regimens that are given for varying durations, with or without ribavirin, depending on the viral genotype, the presence or absence of baseline resistance-associated variants (RAVs), and the patient type. RAVs may be present before exposure to a drug or may become detectable de novo during exposure to a drug. Emerging resistant strains are the most common cause of failure of HCV DAA regimens. Second-generation DAAs provide superior coverage of resistant variants compared with first-generation members of that class. They may also cover a broader range of viral genotypes. Numerous clinical trials have evaluated the safety and efficacy of DAAs in a variety of patient populations, including those with cirrhosis, HIV, and end-stage renal disease. This article evaluates the data from these studies, and discusses recommendations from the American Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (IDSA) guidance document.

GS-9190 is a NS5B non-nucleoside analogue with demonstrated effectiveness in a Phase 1 monotherapy study and in combination with other DAAs for treatment of chronic HCV infection. Here, the resistance profile of GS-9190 monotherapy in a Phase 1b study was investigated. Resistance analysis was performed by population sequencing and allele-specific PCR (AS-PCR) for Y448H with an assay cut-off of 0.5%. Phenotypic susceptibility analyses were performed on patient isolates as well as site-directed mutagenesis of mutations selected during monotherapy. No resistance-associated variants were observed in patients before or after receiving single doses of GS-9190 by population sequencing. In contrast, in patients who received GS-9190 for 8 days, mutations Y448H and Y452H in NS5B were observed by population sequencing in 21/36 (58%) and 2/36 (5.6%) patients, respectively, at Day 8 or Day 14. Among the remaining 15 patients who had no detectable Y448H at Day 8 or Day 14 by population sequencing, low frequencies of Y448H ranging from 1.3 to 9.7% were detected in 14 of 15 patients by AS-PCR. By AS-PCR, Y448H remained detectable at reduced frequency in the majority of patients analysed through 4-6 months of follow-up. Chimeric HCV replicons constructed with the NS5B sequence from patients with Y448H and Y448H + Y452H/Y demonstrated 27-fold and 78.5-fold reduced susceptibility to GS-9190. In conclusion, Y448H was rapidly selected in the majority of patients receiving multiple doses of GS-9190 as monotherapy, despite undetectable levels in pretreatment samples. Y448H confers reduced susceptibility to GS-9190 and other NNIs and persisted in most patients for months post-treatment.

BACKGROUND & AIMS: The new pan-genotypic regimen [sofosbuvir (SOF) and velpatasvir (VEL)] for hepatitis C virus (HCV) has been associated with high efficacy. The aim of this study was to assess patient-reported outcomes (PROs) of this regimen. METHODS: The PRO data (CLDQ-HCV, SF-36, FACIT-F, WPAI) came from the ASTRAL-1 study, a multicenter multinational blinded placebo-controlled phase 3 clinical trial of a fixed dose combination of SOF 400mg and VEL 100mg for patients with genotype 1, 2, 4, 5, and 6 compared to placebo for 12weeks. RESULTS: 624 patients received active treatment [618 achieved sustained virologic response (SVR)], and 116 received placebo. The baseline PRO scores were similar. By treatment week 4, patients receiving SOF/VEL experienced improvements in general health (on average, +2.3points), emotional well-being (+3.4), FACIT-F (+1.3), and all domains of CLDQ-HCV (+2.1 to +7.3) (all p<0.005). On the other hand, the only PRO that improved in patients receiving placebo was the worry domain of CLDQ-HCV: +4.6 (p=0.002). By the end of treatment, improvement in PRO scores with SOF/VEL continued, and no improvement was noted in the placebo. Improvement in PROs were also noted 12 and 24weeks post-treatment: +3.7, on average, in patients with SVR-12 after SOF/VEL vs. -2.6, on average, in the placebo arm (p<0.005). Multivariate analysis showed that treatment-emergent changes in PROs were predicted by receiving SOF/VEL for some summary PRO score (p<0.005). CONCLUSIONS: This placebo-controlled trial shows that patients treated with SOF/VEL experience significant improvement of their PROs during treatment and after achieving SVR. LAY SUMMARY: In patients with chronic hepatitis C infection, health-related quality of life and work productivity are often impaired due to HCV-related fatigue. Treatment of hepatitis C with interferon-based regimens, which was the standard of care for all HCV patients until recently, had substantial and potentially debilitating side effects. These regimens caused additional impairment in health-related quality of life and work productivity during treatment and shortly after treatment cessation. The newly developed interferon-free combination of sofosbuvir and velpatasvir has been shown to improve health-related quality of life during treatment, and lead to an improvement in a number of indicators of patient-reported outcomes after successful clearance of HCV and achieving sustained virologic response.