By Liz Highleyman

Tenofovir (Viread)

Emtricitabine (Emtriva)

The nucleotide reverse transcriptase inhibitor tenofovir (Viread, also in the Truvada and Atripla combination pills) is widely prescribed for the treatment of HIV, and was also recently approved for chronic hepatitis B virus (HBV) infection.

Current guidelines recommend that HIV-HBV coinfected patients who require hepatitis B treatment should receive a combination HAART regimen that contains drugs active against both viruses. In addition to tenofovir, such agents include lamivudine (3TC, Epivir), emtricitabine (Emtriva, also in the Truvada and Atripla pills), and -- to a lesser extent -- entecavir (Baraclude).

As described in a poster presented at the 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008), taking place this week in Washington, DC, researchers assessed the efficacy of combination therapy with tenofovir plus emtricitabine by means of a retrospective chart review.

The analysis included 31 HIV-HBV coinfected patients. 12 lamivudine-naive patients were prescribed tenofovir plus emtricitabine as part of their antiretroviral regimen; at baseline, these patients had a median HBV DNA level of 5.8 x 10(7) copies/mL. 19 treatment-experience patients who had previously failed lamivudine therapy were prescribed tenofovir plus emtricitabine after lamivudine failure; this group had a median HBV viral load of 7.6 x 10(7) copies/mL.

Results

• The median time to complete HBV suppression in the lamivudine-naive group was 466 days, compared with 877 days in the lamivudine-experienced group (P = 0.001).

• After 12 months, 60% of the lamivudine-naive patients achieved undetectable HBV DNA (< 200 copies/mL) compared with 21% in the lamivudine-experienced group (P = 0.092).

• After 24 months, 100% of the remaining lamivudine-naive patients, but only 31% of the lamivudine-experienced group, had undetectable HBV DNA (P=0.015).

• Among initially hepatitis B "e" antigen (HBeAg) positive patients, 14% in the lamivudine-naive group and 9% in the lamivudine-experienced group experienced HBeAg loss.

"HBV DNA suppression to under 200 copies/mL was achieved significantly more rapidly among treatment-naive patients," the investigators stated.

"There was a trend towards a greater proportion of naive patients with HBV suppression at 12 months, and a significantly greater proportion of naive patients were suppressed at 24 months," they added. "Loss of HBe antigen was uncommon and not significantly different between the two groups."

Based on these findings, they concluded, "Our results support the practice of initial dual therapy" in HIV-HBV coinfected patients.

New York Univ., New York, NY

10/28/08

Reference
CA Engell, RS Holzman, and JA Aberg. Efficacy of Tenofovir Plus Emtricitabine in Treatment of HIV/HBV Coinfected Patients. 48th International Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2008). Washington, DC. October 25-28, 2008. Abstract V-1626.