Clinical

- Adefovir resistance may present sooner than thought

Last Updated: 2006-10-13 16:15:29 -0400 (Reuters Health)

By Megan Rauscher

NEW YORK (Reuters Health) - Emergence of an adefovir dipivoxil (ADV) mutation during ADV therapy in lamivudine (LMV) resistant chronic hepatitis B patients appears to present "earlier and more frequently" than in treatment-na�ve patients, clinicians from Korea report in the October issue of Gut.

In reports to date, the cumulative incidence of an ADV resistant mutation in nucleoside/nucleotide treatment na�ve chronic hepatitis B patients at weeks 48, 96, and 144 was 0, 0.8-3%, and roughly 5.9%, respectively, note Dr. Chang Hong Lee from Konkuk University Hospital, Seoul, and colleagues.

They determined the incidence of ADV mutation and its effect on antiviral efficacy in 67 LMV resistant ADV-treated patients. A total of 11 ADV mutations were detected in a total of nine patients during ADV treatment.

"Our data showed the cumulative incidence of genotypic adefovir resistance at months 12 and 24 was 6.4% and 25.4%, respectively," Dr. Lee told Reuters Health. This is higher than has been reported.

The first cases of ADV resistance mutations were detected as early as three months after three months of ADV therapy.

The clinical course of the patients after emergence of an ADV mutation was variable. During ADV treatment, three of nine ADV mutant patients developed HBV DNA rebound. Eight of nine patients with an ADV mutation had cirrhosis.

"Lamivudine is the most widely used antiviral agent for chronic hepatitis B in Asia," Dr. Lee noted. "Adefovir is useful for the treatment of lamivudine resistant cases. However, recent clinical observations as well as our data demonstrate that resistance to one drug may prone to emergence of resistance to other drugs as in the case of antiviral therapy for HIV."

"Preventive and optimal therapeutic measures for multi-drug resistant HBV should be needed in the near future," the clinician predicts.

Gut 2006;55:1488-1495.