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Tenofovir effective in patients with chronic HBV resistant to previous NRTI therapy

BOSTON — Most patients with chronic HBV treated with tenofovir experienced viral suppression after failing earlier therapy with nucleos(t)ide reverse transcriptase polymerse inhibitors in a study presented at The Liver Meeting 2012.

Researchers evaluated medical records for 220 patients with chronic HBV treated at the Toronto Western Hospital Liver Centre who received tenofovir after indicating resistance to one or more nucleos(t)ide reverse transcriptase polymerse inhibitors (NRTI). Among these patients, 62.3% had an M204 mutation, 2.3% an A181T or N236T mutation, and 35.4% had experienced virologic breakthrough despite continued treatment with NRTI. NRTI resistance was addressed via interferon, adefovir, lamivudine or entecavir, along with some participants who received tenofovir monotherapy.

“Lamivudine is the first NRTI to be approved for treating HBV infection,” the researchers wrote. “This class of antiviral therapy suppresses HBV replication, but long-term treatment is required since HBV is not eradicated. There is concern that uncontrollable multidrug-resistant HBV infection might emerge from long-term treatment.”

At tenofovir initiation, 65 participants in the cohort already had experienced full viral suppression (HBV DNA levels less than 60 IU/mL). All continued to have levels less than 60 IU/mL while on tenofovir, for a mean of 26.5 months of follow-up. The remaining 156 patients had average HBV DNA levels of 4.5 log IU/mL upon study initiation, with 91% of these participants achieving full suppression within 12 months (median time 3.6 months). Nearly all participants eventually became HBV DNA-negative, with seven participants maintaining a mean viral load of 2.5 log IU/mL after a mean follow-up of 16.5 months.

Virologic breakthrough occurred in two patients, but investigators attributed both incidents to noncompliance, and both patients achieved suppression upon treatment compliance. Among 77 patients who were hepatitis B e antigen-positive, loss occurred in 30% of cases.

“People who fail other medications for hepatitis B do well on tenofovir,” researcher Jeffrey So, MD, formerly a fellow at the hepatology department of the , told Healio.com. “In places where tenofovir isn’t that successful or affordable, using lamivudine as first-line therapy isn’t necessarily a bad thing, because you always have [tenofovir] as a backup. You don’t have to put everybody on this from the get-go.”

Disclosure: The researchers report numerous financial disclosures.

For more information:

So J. #364: Tenofovir monotherapy is effective salvage therapy of nucleoside-resistant hepatitis B. Presented at: The Liver Meeting 2012; Nov. 9-13, Boston.