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Combination HIV Drug Trizivir, Along With Tenofovir, Well Tolerated: Presented at ICAAC

By Paula Moyer

WASHINGTON, DC -- December 22, 2005 -- In the near future, patients with HIV-1 who are taking their first antiretroviral therapy regimen may be able to manage their disease with a once-daily regimen that includes 1 tablet combining 3 antiretrovirals (Trizivir) and 1 tablet of tenofovir (Viread), according to research presented here at the 45^th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).

"In subjects who are naïve to antiretroviral therapy, this treatment combination given as a once-daily regimen provided virologic suppression for subjects who remained on therapy," according to principal investigator Cal Cohen, MD, research director, Community Research Initiative of New England, and clinical instructor, Harvard Medical School, Boston, Massachusetts.

The combination tablet contains 300 mg of abacavir (Ziagen), 300 mg of zidovudine (Retrovir), and 150 mg of lamivudine (Epivir).

"Given the need for simple regimens with fewer drug interactions, a fully powered study is needed to establish the role of [such a] regimen for initial HIV treatment," Dr. Cohen said in a presentation on December 16^th.

He noted that additional protease inhibitor-sparing and nucleoside reverse transcriptase inhibitor-sparing therapeutic options are needed for several HIV populations, including women of childbearing age, patients with psychiatric illnesses, patients coinfected with hepatitis B or C, and patients on tuberculosis medications with rifampin-based therapy.

The investigators conducted an open-label, multicenter study to evaluate the feasibility of using the combination pill Trizivir along with tenofovir, a regimen that consisted of 3 pills taken once daily.

The 123 subjects had an HIV-1 RNA viral load of at least 30,000 c/mL at the time of study entry. In 13 subjects, the investigators assessed changes from baseline in fat distribution and bone density by whole body and regional dual energy x-ray absorptiometry (DEXA) at 1 site.

Patients were a median of 38 years old (range 20-57 years), and 74% were asymptomatic. Among these patients, 83% were male and 46% were Caucasian, with 41% African American. The median viral load was 5.1 log₁₀ copies/mL, with 59% having a viral load of at least 100,000 c/mL. The median CD4+ was 222 cells/mm³, with 45% having more than 200 cells/mm³.

A total of 52 subjects withdrew early -- 14 for adverse events, 13 lost to follow-up, 12 for virologic nonresponse, and 13 for other reasons. A viral load of at least 400 c/mL at week 24 or later -- the study's definition of virologic failure -- was noted in 14 subjects (11%). The resistance rate to abacavir was 6.5%.

At week 48, the intent-to-treat (ITT) analysis, involving 68 patients, showed that 41% achieved viral load < 50 c/mL and 51% achieved a viral load < 400 c/mL. The ITT observed analysis showed that 75% had a viral load of < 50 c/mL and 93% had a viral load < 400 c/mL. The median CD4+ change from baseline was an increase of 127 cells/mm³.

By the end of the study, the median changes for fasting lipid levels were a decrease of 9 mg/dL for total cholesterol, an increase of 1 mg/dL for high-density lipoproteins, a decrease of -9 mg/dL for low-density lipoproteins, and a decrease of 4 mg/dL for triglycerides.

In the subset of patients with body fat and bone density analysis, the median changes were a gain of 9% in arm fat, a gain of 11% in leg fat, and a gain of 14% in trunk fat. Bone mineral density was not changed.

The investigators concluded that in antiretroviral therapy-naïve subjects, this once-daily regimen provided virologic suppression and improved fasting lipids, with neither lipoatrophy nor bone loss occurring in the subset of subjects undergoing DEXA.

The approach may be useful as a way to minimize the use of protease inhibitors and non-nucleoside reverse transcriptase inhibitors, the investigators concluded.


[Presentation title: 48 Week Analysis of Efficacy and Safety of Once-Daily (QD) Abacavir/Lamivudine/Zidovudine (Trizivir) + Tenofovir (TDF). Abstract H-521]

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