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25-11-2014 | Infectious disease | Article

Persistence pays with tenofovir for Asian patients with high viral load

Abstract

Free abstract

medwireNews: Tenofovir disoproxil fumarate (TDF) treatment results in viral suppression in Asian or Pacific Islander patients with hepatitis B virus (HBV) infection, even if they have a high viral load, an analysis shows.

It took longer for patients to achieve viral suppression (HBV DNA <400 copies/mL) if they had a high viral load, report Scott Fung (University of Toronto, Ontario, Canada) and co-workers.

“However, delays in achieving virological suppression were not associated with adverse outcomes”, they write in Liver International.

The 205 patients had participated in two randomised trials of TDF 300 mg versus adefovir dipivoxil 10 mg for 48 weeks, followed by open-label TDF for a further 240 weeks. Fung et al chose to analyse the Asian and Pacific Islander participants separately, noting that they account for three-quarters of chronic HBV infections worldwide, yet are underrepresented in clinical trials.

At baseline, 16% of the patients had a high viral load (HBV DNA ≥ 9 log10 copies/mL), and all of these patients were positive for hepatitis B e antigen (HBeAg). By week 48, only 50% of these patients had achieved viral suppression, compared with 81% of patients without a high viral load. And the average HBV DNA level at this point was 3.0 versus 2.3 log10 copies/mL.

However, there was little difference between the two groups after week 72, with 100% of patients with a high viral load and 97% of those without achieving viral suppression, with corresponding average viral loads of 2.2 and 2.3 log10 copies/mL.

Among HBeAg-positive patients, 50% of those with high viral load and 55% of those without achieved HBeAg loss, and 40% and 38%, respectively, achieved seroconversion (development of antibodies against HBeAg). No patient lost hepatitis B s antigen positivity, however, or developed antibodies to it.

Understanding how HBeAg-positive Asian or Pacific Islander patients with a high viral load respond to TDF treatment is “of particular significance”, say the researchers, “because the highest prevalence of HBeAg-positive chronic infection in the world occurs in Oceania, South Asia and Southeast Asia.”

The add that HBeAg-positivity in women of childbearing age increases the risk that they will pass the virus to their babies, which is “a predominant infection route [in] the Asia Pacific region.”

Five patients with high viral load had a single episode of virological breakthrough during treatment, but four of these were found to be nonadherent to medication at the time. There were no cases of resistance to TDF and just 10 patients added emtricitabine therapy.

“The extent of virological suppression and absence of resistance with TDF in this study confirms the effectiveness of TDF as monotherapy”, says the team.

medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2014

By Eleanor McDermid, Senior medwireNews Reporter