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HIV and Hepatitis.com Coverage of
Digestive Disease Week 2006 (DDW 2006)
 May 20 - 25, 2006, Los Angeles, California

Tenofovir More Potent than Adefovir Against Lamivudine-Resistant HBV

Management of patients with hepatitis B virus (HBV) that has developed resistance to lamivudine (Epivir-HBV) remains a challenge. This study compared adefovir (Hepsera), which was approved for hepatitis B treatment in 2002, against tenofovir, a structurally similar agent currently approved for HIV treatment.

The study included 109 participants (all but one Asian) with chronic hepatitis B who experienced virological breakthrough during treatment with lamivudine. Patients were assigned to receive adefovir or tenofovir for six months or longer. Baseline characteristics were similar in the two arms. Some patients in both arms continued on lamivudine or had it added later.

Results

The mean reduction in HBV viral load was greater in the tenofovir arm compared with the adefovir arm at six and 12 months. In addition, a larger proportion of patients in the tenofovir arm had at least a 3 log reduction in HBV DNA at 12 months. Among patients who took both tenofovir and lamivudine, HBV DNA reduction at six months was greater than the reduction seen among those who took either adefovir monotherapy or adefovir plus lamivudine. No subjects in any group experienced virological breakthrough after suppression during up to 38 months of follow-up observation.

HBeAg loss occurred in 4.5% of patients in the tenofovir arm and 7.7% in the adefovir arm after 24 months. Alanine aminotransferase (ALT) levels normalized in 55% of patients in the tenofovir arm and 66% in the adefovir arm after six months. Both differences were non-significant.

 

TNV

ADV

P value

No. Patients

44 (12 with LAM)

65 (18 with LAM)

 

Duration of Treatment

13 mos (6-38)

17 mos (6-34)

 

Baseline HBV DNA (log10 copies/ml)

6.23+/-1.66

6.49+/-1.56

0.404

Mean HBV DNA log reduction (6 mos)

3.65+/-1.75 (n=30)

1.94+/-1.98 (n=45)

0.00

Mean HBV DNA log reduction (12 mos)

5.03+/-1.64 (n=15)

2.36+/-2.37 (n=42)

0.00

DNA reduction > 3 log

63%

28%

0.013

HBeAg loss (in 24 mos)

4.5% (2/44)

7.7%
(5/65)

0.699

ADV = adefovir; LAM = lamivudine; TNV = tenofovir

Conclusion

The researchers concluded that for patients with lamivudine-resistant HBV, tenofovir alone or in combination with lamivudine “exerts a greater viral reduction” than adefovir. However, there was no significant difference in HBeAg loss or ALT normalization, suggesting that a larger reduction in HBV viral load “may not necessarily speed up HBeAg loss.”

6/0/06

Reference
H.L. Hann, H. Chae, S.R. Dunn. Tenofovir (TNV) has a stronger antiviral effect than adefovir dipivoxil (ADV) against lamivudine (LAM) resistant hepatitis B virus (HBV). Abstract T1841. DDW 2006. May 20-25, 2006. Los Angeles, CA.


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