Stepwise process for the development of entecavir resistance in a chronic hepatitis B virus infected patient

Antiviral drug-resistant HBV

“…47 HBV isolates with ETV-associated mutations are sensitive to adefovir and tenofovir in vitro and in vivo data confirming the efficacy of adefovir has been reported in one patient. 61 Recent data suggest that pre-existence of mutations such as rtL180M ϩ rtM204V even when present in Ͻ0.1% of the viral population in patients who have not received lamivudine treatment may increase the risk of selection for ETV-associated mutations in patients receiving entecavir treatment. 62 In addition, virologic breakthrough may occur in nucleoside-naïve patients receiving entecavir treatment due to selection of LAMassociated mutations alone.…”

Two cases of development of entecavir resistance during entecavir treatment for nucleoside-naive chronic hepatitis B

“…In the first case, the patient received a lower dose of ETV (0.1 mg daily for 52 weeks) than is currently recommended in product labeling. It was shown that LVD-ADV combination therapy was apparently effective for the ETV-resistant strain, presumably because there is no cross-resistance between ETV and ADV [26,27].…”

Perspectives on the management of chronic hepatitis B and C

“…The continued use of single nucleosides with high rates of resistance in sequence, as in the past, may lead to the development of multidrug-resistant HBV [8,9]. The disadvantages of using a monotherapy with high rates of resistance may be lessened by the application of sensitive techniques to detect the emergence of viral resistance at a stage before the risk of clinically adverse events.…”