Prevention and management of drug resistant hepatitis B virus infections.

In the past decade, broadened therapeutic options of oral direct antiviral agents for the treatment of chronic hepatitis B infection include: Lamivudine, Adefovir Dipivoxil, Telbivudine, Entecavir and Tenofovir Disoproxil Fumarate. These direct oral antiviral agents effectively suppress the replication of the virus and reduce the risk of potential liver-related complications. However, prolonged use of these nucleos(t)ide analogues has been associated with drug resistance that compromises the initial clinical benefits. Moreover, the oncogenic risk of mutations due to prolonged nucleos(t)ide analogue therapy needs to be further investigated by in vitro and in vivo studies. In the current era of potent nucleotide analogues, new data are emerging, we are still facing the pool of patients who have developed resistance to the prior generation of nucleos(t)ide analogues. This paper aims to focus on incidence of antiviral drug resistance and virological breakthrough, prudent selection of initial therapy, on-treatment monitoring for drug resistance and revise treatment strategies for patients with resistant virus.