Partial virological response to entecavir treatment in nucleos(t)ide-naïve patients with HBeAg-positive chronic hepatitis B is not caused by reduced sensitivity

Low-level viremia in nucleoside analog-treated chronic hepatitis B patients

ABSTRACT

Low-level viremia (LLV) was defined as persistent or intermittent episodes of detectable hepatitis B virus (HBV) DNA (<2000 IU/mL, detection limit of 10 IU/mL) after 48 weeks of antiviral treatment. Effective antiviral therapies for chronic hepatitis B (CHB) patients, such as entecavir (ETV), tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF), have been shown to inhibit the replication of HBV DNA and prevent liver-related complications. However, even with long-term antiviral therapy, there are still a number of patients with persistent or intermittent LLV. At present, the research on LLV to address whether adversely affect the clinical outcome is limited, and the follow-up treatment for these patients is open to question. At the same time, the mechanism of LLV is not clear. In this review, we summarize the incidence of LLV, the association between LLV and long-term outcomes, possible mechanisms, and management strategies in these patient populations.

Evolution and phenotypic characterization of whole HBV genome in compliant patients experiencing unexplained entecavir treatment failure

Entecavir treatment failure can be observed in compliant patients despite an absence of detectable resistance mutations by Pol/RT Sanger sequencing. We hypothesized that these unexplained treatment failures could rely on other mechanisms of viral resistance, especially on mutations selected outside of the Pol/RT domain. Partial virological response to entecavir was observed in three patients treated with immunosuppressive drugs, without selection of Pol/RT resistance mutations. Mutations selected in the whole HBV genome during entecavir treatment and potentially associated with resistance were searched for using deep sequencing and characterized using a phenotypic resistance assay. Mutations Q206K (pre-core/core), Q120K (pre-S1/pre-S2, T-cell epitope) and A300E (spacer domain) were selected during entecavir treatment in patient #1 but were not associated with an increased level of resistance to entecavir or an increase in HBV replication capacity. Core promoter mutations T1753G, A1762T and G1764A were present as major mutations before and after treatment in patient #1. HBs Ag immune escape mutations were present as major mutations before and after treatment in patients #2 (sK122R, sT126I, sP127S and sG145R) and #3 (sM133I). We demonstrated that PVR to entecavir does not require selection of any resistance mutation in the whole HBV genome. Our results demonstrate that major mutations can be selected outside of the Pol/RT domain before or during entecavir treatment. These mutations could contribute to entecavir treatment failure by other mechanisms than an increased level of resistance.

Optimal drug administration manner would rescue partial virological response in chronic hepatitis B patients with entecavir or tenofovir treatment

Not all treatment-naïve patients receiving entecavir (ETV) or tenofovir disoproxil fumarate (TDF) therapy can achieve complete virological response, and many factors may be related with the outcome of partial virological response. This study aimed to determine whether the manner of drug administration affects the antiviral efficacy of ETV/TDF monotherapy. All eligible patients were divided into complete or partial response cohorts based on their virological response following 24-week therapy. Factors related with partial response were evaluated. Patients with partial response were further grouped depending on whether they later adjusted the manner of drug administration, and the antiviral efficacy was compared between the two groups during prolonged treatment. A total of 518 patients were enrolled. Suboptimal drug administration (OR 77.511, P = .000), positive-HBeAg (OR 3.191, P = .000) and ETV treatment (OR 2.537, P = .001) were identified as independent risk factors for partial response. Among patients with partial response, 213 were in the adjusted group and 76 were in the unadjusted group. The percentages of patients with undetectable serum HBV DNA (78.9% vs 31.6%, P < .001) and with normal alanine aminotransferase (ALT) (88.7% vs 68.4%, P < .001) were both higher in the adjusted group than that in unadjusted group following a further 6-month therapy. In conclusion, the manner of drug administration is an important factor influencing the efficacy of ETV/TDF therapy, and optimal drug administration manner can help to increase antiviral efficacy and rescue patients with partial response.