new etv resistance mutant found (it also shares lam, adv res)

Received 11 August 2011; revised 14 October 2011; Accepted 18 October 2011. Available online 9 November 2011.

Abstract
Background
Prolonged antiviral treatment results in selection and accumulation of resistant strains in quasispecies pool in hepatitis B virus (HBV) infection.

Objectives
The aim of this study was to characterise a novel HBV pattern which shows resistance to lamivudine, adefovir dipivoxil and entecavir using in vitro phenoyping assay.

Study design
A male 36 years old patient diagnosed with anti HBe-positive chronic hepatitis B (CHB) had received lamivudine treatment for 7 years following an initial unsuccessfull interferon treatment. The therapy had been switched to adefovir and then to entecavir when breakthrough occcured during each treatment. This led only to a temporary HBV DNA decline which soon was followed by viral breakthrough despite the lack of known entecavir resistance mutations. Patient died after 9 months of entecavir treatment from liver failure. A total of 434 clones from 6 different serum samples were analysed retrospectively. HBV genomes bearing mutation patterns suggestive of antiviral resistance were analysed by in vitro phenotyping assay.

Results
Dominance of a clone carrying L80LV, L91I, M204I, S219A, N238D, Y245H changes was detected in the last serum sample of the patient just before his death. This pattern displayed 30.4 fold resistance to entecavir when compared with the wild type HBV by in vitro phenotyping assay.

Conclusion
A novel mutation pattern showing a high degree of resistance to entecavir was documented. In this pattern, the S219A and Y245H mutations mainly seem to contribute to the emergence of ETV resistance.

[stef2011]

i think we are getting clearer day by day only tenofovir is very very safe, despite etv has only 1.2% resistance if lam mutants or these new mutants are present resistance becomes extremely high simialr to lam percentages

[MiddleAge67]

Entecavir (LAM resistant) 6%(1 year) 15%(2 year) 36%(3 year) 46%(4 year) 51%(5 year) 57%(6 year)

From:
Hepatitis B Virus Resistance to Nucleos(t)ide Analogues
REVIEWS IN BASIC AND CLINICAL GASTROENTEROLOGY
GASTROENTEROLOGY 2009;137:1593–1608

It is clear that LAM resistance could NOT be rescued by ENT.

Dan

[StephenCastlecrag]

It is well known (now) that Ent is not efficacious as a rescue therapy for LAM resistance. This paper highlights a pattern of mutations that seems to confer 30 fold increase to resistance to ENT in testing in test-tube. It is a warning that an accumulation of drug-related mutations may be very dangerous.

Just my opinion.

[Bob0620]

Hope Tenofovir can prevent future mutations