Novel drug resistance-associated substitutions against pibrentasvir emerged in genotype 1b hepatitis C virus-infected human hepatocyte transplanted mice

Combination therapy with glecaprevir and pibrentasvir (PIB) has high efficacy for patients with hepatitis C virus (HCV) infection except among those who experienced NS5A-P32 deletion (del) mutation during prior DAA treatment failure. However, some patients fail to achieve SVR through combination treatment even in the absence of NS5A-P32del. We analyzed emergence of NS5A resistance-associated substitutions (RASs) against PIB using HCV-infected mice. Male human hepatocyte transplanted mice were infected with genotype 1b wild-type HCV. Mice were treated with PIB, resulting in a transient decrease in serum HCV RNA levels but followed by relapse during the treatment. Direct sequence analysis showed emergences of various mutations in the NS5A region, including L31V/P32del, L31F/P32del/Y93H, NS5A-P29del/Y85C, and NS5A-F37Y. PIB was less effective in mice with NS5A-F37Y mutations compared to mice with wild-type HCV. NS5A-F37Y showed 5.4-fold resistance to PIB relative to wild-type based on analysis using HCV subgenomic replicon systems. The present in vivo and in vitro studies identified NS5A-F37Y as a novel RAS against PIB and showed the possibility of emergence of various NS5A RASs including P29del, P32del and F37Y following PIB treatment. These mutations might emerge and lead to failure to respond to DAA therapies including PIB-based regimens in chronic hepatitis C patients.

Prevalence of NS5A resistance associated variants in NS5A inhibitor treatment failures and an effective treatment for NS5A-P32 deleted hepatitis C virus in humanized mice

Patients with chronic hepatitis C virus (HCV) infection who have failed to respond to direct-acting antiviral (DAA) treatment often acquire drug resistance-associated variants (RAVs). The NS5A-P32 deletion (P32del) RAV confers potent resistance to NS5A inhibitors; therefore, patients who acquire this deletion are likely to fail to respond to DAA re-treatment. We investigated the prevalence of N55A-P32del in patients who failed to respond to prior NS5A inhibitor treatment using direct sequencing and analyzed the efficacy of DAA combination treatment in the presence of NS5A-P32del RAVs using human hepatocyte transplanted mice. NS5A-P32del was detected in one of 23 (4.3%) patients who had failed to respond to prior NS5A inhibitor treatment. Although four weeks of NS3/4A protease inhibitor glecaprevir plus NS5A inhibitor pibrentasvir treatment effectively suppressed HCV replication in wild-type HCV-infected mice, serum HCV RNA never became negative in P32del HCV-infected mice. When P32del HCV-infected mice were treated with four weeks of glecaprevir plus pibrentasvir combined with the NS5B polymerase inhibitor sofosbuvir, serum HCV RNA became negative, and the virus was eliminated from the liver in three out of four mice. We conclude that the combination of sofosbuvir and glecaprevir plus pibrentasvir may be an effective new treatment option for patients with NS5A-P32del.

Antiviral effects of anti-HBs immunoglobulin and vaccine on HBs antigen seroclearance for chronic hepatitis B infection

BACKGROUND AND AIMS

Interferon and nucleotide/nucleoside analogues are the main treatments for chronic hepatitis B. These drugs effectively reduce serum hepatitis B virus (HBV) DNA titers but fail to sufficiently reduce hepatitis B surface antigen (HBsAg) levels. Following the recent identification of sodium taurocholate cotransporting polypeptide as a receptor for HBV entry, inhibition of HBV entry has become an attractive therapeutic target for chronic hepatitis B treatment. We therefore evaluated the antiviral effects of antibody to HBsAg (anti-HBs) immunoglobulin (HBIG), which can inhibit HBV entry, by in an vivo study and a clinical trial.

METHODS

In the in vivo study, HBV-infected mice were generated from human hepatocyte chimeric mice and treated with HBIG. A clinical trial evaluating HBIG therapy in patients was also performed.

RESULTS

In the mouse study, HBV DNA titers were reduced and serum HBsAg titers decreased to undetectable levels following high-dose HBIG injection. On the basis of this result, eight chronic hepatitis B patients, who had received long-term nucleotide analogue treatment, were treated with monthly HBIG injections as an additional treatment. After 1 year of treatment, an HBsAg level reduction of more than 1 log IU/mL was observed in four patients, and three patients became anti-HBs positive. No adverse events occurred during HBIG therapy.

CONCLUSION

These results suggest that monthly HBIG injection might benefit patients with chronic hepatitis B whose HBsAg titer becomes lower following long-term nucleotide/nucleoside analogue treatment.