Current practice and contrasting views on discontinuation of nucleos(t)ide analog therapy in chronic hepatitis B

How to achieve functional cure of HBV: Stopping NUCs, adding interferon or new drug development?

Functional cure of hepatitis B is defined as sustained undetectable circulating HBsAg and HBV DNA after a finite course of treatment. Barriers to HBV cure include the reservoirs for HBV replication and antigen production (covalently closed circular DNA [cccDNA] and integrated HBV DNA), the high viral burden (HBV DNA and HBsAg) and the impaired host innate and adaptive immune responses against HBV. Current HBV therapeutics, 1 year of pegylated-interferon-α (PEG-IFNα) and long-term nucleos(t)ide analogues (NUCs), rarely achieve HBV cure. Stopping NUC therapy may lead to functional cure in some Caucasian patients but rarely in Asian patients. Switching from a NUC to IFN after HBV DNA suppression increases the chance of HBsAg clearance mainly in those with low HBsAg levels. Novel antiviral strategies that inhibit viral entry, translation and secretion of HBsAg, modulate capsid assembly, or target cccDNA transcription/degradation have shown promise in clinical trials. Novel immunomodulatory approaches including checkpoint inhibitors, metabolic modulation of T cells, therapeutic vaccines, adoptive transfer of genetically engineered T cells, and stimulation of innate and B-cell immune responses are being explored. These novel approaches may be further combined with NUCs or PEG-IFNα in personalised strategies, according to virologic and disease characteristics, to maximise the chance of HBV cure. The development of curative HBV therapies should be coupled with the development of standardised and validated virologic and immunologic assays to confirm target engagement and to assess response. In addition to efficacy, curative therapies must be safe and affordable to meet the goal of global elimination of hepatitis B.

Hepatocellular carcinoma after treatment cessation in non-cirrhotic HBeAg-negative chronic hepatitis B: A multicentre cohort study

BACKGROUND AND AIMS

Scarce data exist on the effect of nucleos(t)ide analogue (NA) discontinuation on hepatocellular carcinoma (HCC) risk in HBeAg-negative chronic hepatitis B (CHBe-). Therefore, we assessed whether HCC risk is increased in non-cirrhotic CHBe- patients who discontinue compared to those remaining on NAs.

METHODS

This cohort study included 650 consecutive non-cirrhotic Caucasian or Asian patients with CHBe- without a history of HCC who discontinued NAs after a median of 5 or 3 years (cases, n = 325; Caucasians: 143, Asians: 182) or remained on NA therapy beyond 5 or 3 years respectively (controls, n = 325; Caucasians: 223, Asians: 102). Propensity score (PS) 1:1 matching was applied to adjust for patients' origin, age and sex.

RESULTS

During a median follow-up of 44 months, HCC developed in 7/325 cases and 9/325 controls or 7/245 PS-matched cases and 7/245 PS-matched controls with 5-year cumulative HCC incidence of 5.1% and 4.9% respectively (log-rank, P = .836). No difference in 5-year HCC risk was observed between cases and controls of Caucasian (3.0% vs 4.8%; log-rank, P = .510) or Asian origin (1.3% vs 2.2%; log-rank, P = .873). In both cases and controls, HCC incidence was independently associated with age and PAGE-B score. In cases alone, HCC development after NA discontinuation was associated only with pretreatment platelet counts and PAGE-B score, but not with any type of relapse or HBsAg loss.

CONCLUSIONS

Our findings suggest that discontinuation of effective long-term NA therapy in non-cirrhotic CHBe- patients are not associated with increased HCC risk, which is not affected by post-NA relapses and/or HBsAg loss.

Serum hepatitis B virus RNA detectability, composition and clinical significance in patients with ab initio hepatitis B e antigen negative chronic hepatitis B

Background

Serum hepatitis B virus (HBV) RNA is a surrogate biomarker for intrahepatic covalently closed circular DNA (cccDNA) transcriptional activity and persistence. In this retrospective study, we investigated its presence, levels and composition in ab initio Hepatitis B e antigen (HBeAg) negative chronically infected patients and examined possible associations with disease activity and the outcome of nucleos(t)ide analogue (NA) discontinuation.

Methods

We developed a sensitive real time polymerase chain reaction (RT-PCR) for the specific detection of HBV pregenomic RNA (pgRNA) and precore (preC) mRNA and analyzed 220 serum specimens, 160 under NA treatment, from 116 Greek patients initially negative for HBeAg.

Results

HBV pgRNA was detected in 31% and preC mRNA in 15% of samples, at lower levels representing a small fraction (3.4%) of total core promoter produced transcripts. In the absence of NAs, pgRNA was detected in 57% of samples with median value of 5.19 (2.61–8.35) log₁₀ cp/mL, at lower levels than HBV DNA and correlated significantly with ALT (r = 0.764) and serum HBV DNA (r = 0.906). A wide range of HBV DNA/pgRNA ratio was observed with significant inter- and intra-patient variation. During NA treatment, pgRNA displayed low detectability (22%) and variable levels, median 3.97 (2.30– 8.13) log₁₀ cp/mL, as well as, a significant inverse correlation with the duration of treatment (r = − 0.346, p < 0.01). In 74 events of NA discontinuation, end-of-treatment pgRNA-positive compared to pgRNA-negative cases, experienced more frequently virological (p = 0.016) and clinical (p = 0.011) relapse.

Conclusions

In genotype D ab initio HBeAg negative patients, serum HBV RNA is primarily composed of pgRNA plus a minor fraction of preC mRNA transcripts. Serum pgRNA is associated with disease activity, suggesting lysis of infected hepatocytes as a possible source of serum HBV RNA in untreated patients and in the early phase of NA treatment. During long term NA treatment, detectable serum pgRNA predicts viral rebound and clinical relapse following treatment discontinuation and may thus serve as a marker for the decision of cessation of therapy.

Perspectives on stopping nucleos(t)ide analogues therapy in patients with chronic hepatitis B

Long-term treatment with nucleos(t)ide analogs (NAs) is the current first line therapy for patients with chronic hepatitis B (CHB), recommended by most of the current guidelines. NAs prevent disease progression, liver failure, decrease the risk of hepatocellular carcinoma (HCC), and have favorable safety profiles. However, low rates of on-therapy functional cure (hepatitis B surface antigen [HBsAg] loss), which is regarded as the optimal end point, prevent many patients from stopping NA therapy with the need for a lifelong treatment. The higher likelihood of HBsAg loss associated with stopping as compared to continuing NAs has got a lot of attention recently. Recommendations regarding endpoints allowing for safely stopping NA therapy differ between international guidelines. Whereas in HBeAg-positive patients, HBeAg seroconversion with at least one year of consolidation therapy is an acceptable endpoint of treatment, the recommendations for HBeAg-negative ones differ. Some guidelines propose ≥3 years of HBV DNA undetectability to stop NA while others regard HBsAg loss as the only acceptable endpoint. Stopping NA can lead to substantial rates of virologic relapses and consequent ALT flares in some cases. Moreover, no reliable predictor(s) of post-NA relapses have been identified so far. Quantitative HBsAg is becoming an increasingly promising marker to predict safe NA cessation. On the other hand, investigating the role of the immune system in mediating sustained virologic responses after NA withdrawal is needed to suggest immunological biomarkers to safely stop NA. In this article, we will review relevant literature regarding NA stopping strategy and discuss promising viral and immunological biomarkers to predict antiviral responses and thus to help identify patients who are more likely to achieve HBsAg seroclearance.