Entecavir (Baraclude)
and tenofovir (Viread) both
demonstrated potent activity against hepatitis B virus (HBV) in a Turkish study
presented at the IDWeek 2013 conference held recently in San Francisco.
Entecavir appeared to have an edge with regard to hepatitis B 'e' antigen
(HBeAg) seroconversion, but this rose with time amongst people taking either
drug.
The nucleoside/nucleotide analogues entecavir
and tenofovir are two of the most effective hepatitis B drugs available. They
have a high genetic barrier to resistance and both have been shown to reduce
HBV viral load over the long term. Viral replication often rebounds after
stopping treatment, however, and it is more difficult to achieve serological
endpoints such as HBV antigen loss or antibody seroconversion.
Fehmi Tabak from Cerrahpasa Medical Faculty in Istanbul and colleagues with the REALIST
Study Group evaluated outpatient hepatitis B treatment using entecavir or
tenofovir in a 'real world' clinical setting.
REALIST is an ongoing observational study of more than 500 previously
untreated chronic hepatitis B patients seen at eleven centres in Turkey since
November 2008.
The present analysis included 264 patients, 134 of them treated with
entecavir and 130 treated with tenofovir. The researchers' poster did not
describe demographic characteristics of the study population.
At baseline HBV DNA viral load, alanine aminotransferase (ALT) levels
and liver fibrosis scores were similar in the two treatment groups; 28% of
people taking entecavir and 35% taking tenofovir were HBeAg positive. The average
treatment duration was 32 months for entecavir and 27 months for tenofovir.
Entecavir and tenofovir both rapidly reduced HBV DNA levels after
starting treatment. There were no significant differences between the two
groups in the proportion of patients achieving undetectable HBV DNA or ALT
normalisation after three years of treatment. This was the case for both
HBeAg-positive and HBeAg-negative participants.
After the third year of treatment, the overall HBeAg seroconversion rate
was higher in the entecavir group (38%) compared with the tenofovir group
(20%), a statistically significant difference. However, after adjusting for
factors including patient age, sex, baseline HBV DNA and ALT, the difference
was no longer significant.
"In real-world clinical practice, entecavir
and tenofovir provided comparable efficacy," the researchers concluded.
"HBeAg
seroconversion rates at [the] third year seemed better with entecavir,"
they continued. "However, it was also observed that HBeAg seroconversion
rates were increasing with time in both groups and were approaching to each
other."