Entecavir

證據等級: L5

預測適應症: 10 個

Entecavir: From Chronic Hepatitis B to Chronic Hepatitis C Virus Infection

One-Sentence Summary

Entecavir is a guanosine nucleoside analogue approved internationally as a first-line treatment for chronic hepatitis B virus (HBV) infection, though it is not currently registered in Australia. The TxGNN model predicts it may have potential activity against Chronic Hepatitis C Virus Infection, with 40 clinical trials and 20 publications identified in the evidence search — the vast majority, however, relate to HBV management or HBV/HCV co-infection scenarios rather than direct HCV treatment.

Quick Overview

Item	Content
Original Indication	Chronic Hepatitis B virus (HBV) infection (internationally approved; not currently registered in Australia)
Predicted New Indication	Chronic Hepatitis C Virus Infection
TxGNN Prediction Score	99.98%
Evidence Level	L4
Australia Market Status	Not Registered
Number of ARTG Entries	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Entecavir is a guanosine deoxyribose nucleoside analogue that selectively inhibits the hepatitis B virus (HBV) DNA polymerase. It acts by mimicking the natural substrate deoxyguanosine triphosphate: once incorporated into the growing viral DNA chain, it causes chain termination. This mechanism blocks all three critical activities of the HBV polymerase — base priming, reverse transcription of the negative-strand DNA from pregenomic RNA, and positive-strand HBV DNA synthesis. Although detailed mechanism of action data was not available in this evidence pack, entecavir is well-characterised internationally as a potent, highly selective HBV antiviral with an exceptionally high barrier to resistance — it is a recommended first-line agent in WHO, EASL, and APASL guidelines for chronic HBV.

The mechanistic rationale for repurposing entecavir to chronic hepatitis C virus (HCV) infection is, however, limited. HCV is an RNA virus that replicates via an RNA-dependent RNA polymerase (NS5B) — a structurally and functionally distinct enzyme from the HBV reverse transcriptase that entecavir targets. Approved anti-HCV nucleoside analogues such as sofosbuvir specifically inhibit NS5B, and entecavir has not demonstrated direct inhibitory activity against HCV NS5B in published preclinical data. Nonetheless, there are plausible reasons why the TxGNN knowledge graph would surface this prediction: both HBV and HCV are hepatotropic viruses causing chronic liver inflammation, drive shared pathological pathways (fibrosis → cirrhosis → hepatocellular carcinoma), and are commonly encountered together in overlapping at-risk patient populations.

Importantly, in clinical practice, entecavir IS used in patients receiving HCV treatment — but its role is limited to suppressing HBV reactivation triggered by direct-acting antiviral (DAA) therapy, not to treating HCV directly. This real-world co-management context is likely captured within the model’s knowledge graph and has informed the prediction. This distinction is critical to interpreting the recommendation.

Clinical Trial Evidence

The trials identified predominantly relate to HBV management; the most HCV-relevant studies are listed below.

Trial Number	Phase	Status	Enrolment	Key Findings
NCT02555943	Phase 2/3	Completed	23	Prospective study of DAA therapy in chronic HCV/HBV co-infected patients; determined incidence and risk factors of HBV reactivation during anti-HCV treatment — entecavir used as HBV prophylaxis rather than HCV treatment
NCT04405011	N/A	Unknown	60	Three-arm randomised study evaluating prophylactic nucleos(t)ide analogue (including entecavir) to prevent HBV reactivation in HCV/HBV co-infected patients receiving DAA therapy for chronic HCV; assessed 12-week vs 24-week prophylaxis duration
NCT01018381	N/A	Completed	130	Randomised study of arabinoxylan rice bran (MGN-3/Biobran) for HCC and hepatitis B and C infection; explored immunomodulatory adjuncts to standard antiviral therapy
NCT01270178	N/A	Unknown	420	Prospective trial of entecavir for chronic HBV in HCC patients post radiofrequency ablation; references anti-HCV therapy as a model for reducing HCC recurrence
NCT00597259	Phase 4	Unknown	294	Pegasys plus entecavir vs entecavir alone for HBeAg-positive CHB; drew on HCV and HIV combination therapy experience as a conceptual framework for combination HBV strategies
NCT00096785	Phase 3	Completed	69	Entecavir vs adefovir in nucleoside-naive CHB adults; established entecavir antiviral activity benchmark relevant to broad hepatitis research context
NCT00065507	Phase 3	Completed	195	Phase IIIb comparison of entecavir 1.0 mg vs adefovir in CHB with hepatic decompensation; established entecavir efficacy in advanced liver disease
NCT03662568	Phase 1	Completed	56	Open-label drug-drug interaction study of morphothiadine mesilate/ritonavir combined with entecavir or TDF in healthy subjects
NCT02532413	Phase 4	Unknown	180	Entecavir monotherapy versus combination with Poly IC for chronic HBV; compared antiviral efficacy of combination immunostimulation approach
NCT06566248	Phase 2	Recruiting	90	Randomised double-blind Phase IIa trial of TQA3810 tablets combined with or without nucleoside analogues (including entecavir) in CHB patients

Literature Evidence

PMID	Year	Type	Journal	Key Findings
36146665	2022	Cohort	Viruses	HCV reactivation in anti-HCV antibody-positive CHB patients following nucleos(t)ide analogue (entecavir/lamivudine) therapy; HCV RNA increased in ~40% of patients during HBV suppression, highlighting viral interaction dynamics
24773464	2014	Review	Expert Opin Pharmacother	Advances in HBV/HCV co-infection treatment; entecavir’s role in preventing HBV reactivation during direct-acting antiviral HCV therapy discussed
22959099	2013	Case Report	Clin Res Hepatol Gastroenterol	HBV/HCV co-infected patient case report; therapeutic challenge of dual viral hepatitis management — entecavir used for HBV component while HCV was managed separately
25027705	2014	Review	Minerva Gastroenterol Dietol	Comparative overview of antiviral medications for HBV and HCV and their renal effects; positions entecavir as HBV-specific with distinct pharmacological profile from HCV agents
21497740	2011	Review	Best Pract Res Clin Gastroenterol	Antiviral treatment impact on fibrosis progression in chronic viral hepatitis B and C; demonstrated shared pathological outcome of fibrosis reversal in both conditions
35327336	2022	Review	Biomedicines	Therapy of chronic viral hepatitis B, C, and D; entecavir and tenofovir contextualised within the broader hepatology treatment landscape
32173307	2020	Review	Clin Res Hepatol Gastroenterol	Present and future management of viral hepatitis B and C in children; contrasts HBV treatment (entecavir) with HCV management approaches and shared liver disease burden
28487602	2017	Review	World J Gastroenterol	HBV infection and alcohol consumption; contextualises HBV and HCV as the two leading causes of HCC and future treatment burden following DAA-driven HCV eradication
16937041	2006	Review	Wien Med Wochenschr	Chronic hepatitis B and C treatment overview; compared pegylated interferon and lamivudine strategies for both infections within a single therapeutic framework
24868325	2014	Review	World J Hepatol	Management of HBV and HCV before and after liver and kidney transplantation; entecavir/tenofovir identified as preferred approach for peri-transplant HBV suppression in dual-infected patients

Australia Market Information

Entecavir is not currently registered in the Australian Register of Therapeutic Goods (ARTG). No ARTG entries were identified in this evidence search.

For reference, entecavir (brand name Baraclude®, Bristol-Myers Squibb) is approved by the US FDA (since March 2005) and the European Medicines Agency for treatment of chronic HBV in adults with evidence of active viral replication and active liver disease. It is similarly approved in many Asian and European jurisdictions. Prescribers seeking full product information should refer to international product labelling (US FDA Prescribing Information or EMA Summary of Product Characteristics) or contact the relevant product sponsor regarding Australian availability.

Safety Considerations

Please refer to the TGA-approved Product Information (PI) for safety information. As entecavir is not currently registered in Australia, no Australian TGA PI is available.

For clinical reference, the following key warnings are documented in international labelling:

Lactic acidosis and severe hepatomegaly with steatosis: A rare but potentially life-threatening class effect of nucleoside/nucleotide analogues; treatment should be suspended if clinical or laboratory findings suggestive of lactic acidosis develop.
Severe acute exacerbation of hepatitis B on discontinuation: Hepatic function should be monitored closely for several months after stopping entecavir in patients with HBV infection.
HIV resistance risk: Entecavir selects for the lamivudine-resistance mutation M184V in HIV; it must not be used as monotherapy in HIV/HBV co-infected patients without a fully suppressive antiretroviral regimen — this is particularly relevant given the HCV/HIV co-infection context of this prediction.
Renal impairment: Dose adjustment required for patients with creatinine clearance below 50 mL/min.

Conclusion and Next Steps

Decision: Hold

Rationale: Despite the TxGNN model’s high confidence score (99.98%), the mechanistic rationale for entecavir treating HCV is weak — entecavir inhibits HBV DNA polymerase reverse transcriptase, which is a fundamentally different enzyme from the HCV NS5B RNA-dependent RNA polymerase targeted by approved HCV antivirals. The clinical trials and literature retrieved are primarily HBV-focused; HCV appears only in the context of co-infection prophylaxis. No direct evidence of anti-HCV efficacy for entecavir has been identified.

To proceed, the following is needed:

Direct in vitro preclinical evidence of entecavir activity against HCV NS5B polymerase or other HCV replication targets
Full mechanism of action (MOA) data from DrugBank to clarify any potential cross-viral enzyme inhibition
Dedicated pharmacokinetic/pharmacodynamic modelling for HCV target engagement at clinically relevant concentrations
Clinical evidence from trials specifically enrolling HCV mono-infected patients (not co-infection prophylaxis studies)
TGA registration pathway assessment and Australian ARTG submission feasibility review
Australian-specific safety review encompassing lactic acidosis risk, renal dosing guidance, HBV reactivation monitoring, and HIV resistance risk in at-risk populations
Australian Product Information (PI) document with complete safety, contraindication, and drug interaction data

⚠️ Disclaimer: This report is generated for research reference purposes only and does not constitute medical advice. Drug repurposing candidates require rigorous clinical validation before therapeutic application.

Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.