Viral Breakthrough After Nucleos(t)ide Analog Therapy

Not all cases of hepatitis B virological breakthrough are related to antiviral drug resistance

WEDNESDAY, June 1 (HealthDay News) -- Virological breakthrough (VBT) is common in patients with chronic hepatitis B (CHB) undergoing nucleos(t)ide analog (NUC) treatment, but is not always related to antiviral drug resistance, according to a study published in the May issue of Hepatology.

Chanunta Hongthanakorn, M.D., from the University of Michigan Health System in Ann Arbor, and colleagues examined the incidence of VBT and genotypic resistance (GR) in reviewed records of 148 patients with CHB receiving NUCs. Patients with VBT during an average follow-up of 37.5 months underwent testing for drug resistance mutations.

The investigators found that 39 patients had at least one VBT. When they were retested, 15 of these patients did not have confirmation of VBT, and only five of these 15 had evidence of GR. At five years, the cumulative probability of VBT was 46.1 percent, confirmed VBT was 29.7 percent, and GR was 33.9 percent. Multivariate analysis showed that the only factor significantly associated with VBT was the failure to achieve undetectable hepatitis B virus (HBV) DNA. For the 10 patients who had VBT but not confirmed VBT or GR, all had decreased serum HBV DNA and nine had undetected HBV DNA an average of 6.8 months after VBT.

"VBT was common in CHB patients receiving NUCs in clinical practice, but nearly 40 percent of the VBTs were not related to antiviral drug resistance. Counseling of CHB patients on medication adherence and confirmation of VBT and/or GR can avoid unnecessary changes in antiviral medications," the authors write.

Two of the study authors disclosed financial ties to the pharmaceutical industry.

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