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Long-term effect of tenofovir in the treatment of lamivudine-resistant HBV in comparison to adefovir
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Reported by Jules Levin
http://www.natap.org
from AASLD
Nov 14, 2005, San Francisco
The authors reported tenofovir produced a "fast & stable" suppression of HBV DNA. No viral breakthroughs were observed in up to 48 months of TDF (n=9). TDF appeared to be superior to adefovir in terms of suppression of HBV DNA, HBeAg loss & HBsAg loss. No severe side effects were reported. Genotypic resistance cumulatively occurred in 1.5% in the first & in the first year with adefovir &5% after 2 years of treatment with adefovir in patients with incomplete response. Preexistence of rtM204V/I mutations seems to influence responsiveness to adefovir. Mean reduction in HBV DNA for tenofovir (n=38) was -5.4 log [range: -3.3 to -7.8] at month 18, and -5.1 log [range: -2.4 to -7.8] at month 12. By month 18, 100% on tenofovir had <400 copies/ml. By comparison, at month 12 viral load reduction for adefovir was mean -2.3 log at month 12, -3.2 log at month 24, and -3.4 log at month 30.
This afternoon at AASLD Florian van Bommel gave an oral presentation of a study evaluating the effiicavy and safety of tenofovir compared to adefovir in 106 lamivudine (3TC) refractory patients. Cohort 1 (n=38) were directly switched to tenofovir (300mg once daily): 21 patients with HBV/HIV coinfection; 12 patients with chronic HBV, no comorbidities; and 5 kidney-transplant patients with chronic HBV. Cohort 2 (n=68) were directly switched to adefovir (10mg once daily), all with chronic HBV, no co-morbidities.
All patients were directly switched to either adefovir or tenofovir. The patients were followed for a mean period of 35±10 [12-49] months in the tenofovir group, and 21±5 [12-31] months in the adefovir group. HBV DNA levels were measured on monthly basis by PCR (Roche Monitor, lower limit of detection=400 copies/ml). Phenotypic lamivudine resistance defined at baseline by HBV DNA >10,000 copies/ml despite ongoing lamivudine resistance. Screening for mutations associated with viral resistance was performed in available serum (52 patients in the adefovir group, 38 in tenofovir group) at baseline and every six months by direct sequencing of the HBV polymerase gene spanning codon 88-244.
van Bommel reported:
there was no evidence for viral resistance.
No toxicity was observed also in patients after renal transplantation.
No differences in responsiveness in HBV/HIV coinfected patients receiving lamivudine + tenofovir and HBV monoinfected patients.
The white line is tenofovir.
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