A randomized, controlled trial of initial anti-retroviral therapy with abacavir/lamivudine/zidovudine twice-daily compared to atazanavir once-daily with lamivudine/zidovudine twice-daily in HIV-infected patients over 48 weeks (ESS100327, the ACTION Study).

Background: Traditional first line regimens containing a non-nucleoside reverse transcriptase inhibitor or protease inhibitor may not be suitable for a subset of antiretroviral-naïve patients such as those with certain co-morbidities, women of child-bearing potential, and intolerability to components of standard first line therapy. This study was conducted to determine if alternate treatment options may meet the needs of both general and special patient populations. The ACTION study was a randomized, open-label, multicenter, 48-week trial that compared the safety and efficacy of a triple nucleoside regimen versus a protease inhibitor plus a dual nucleoside regimen in HIV-1 treatment-naïve subjects.

Results: 279 HIV-infected subjects with HIV-1 RNA (VL) >5000 but < 200,000 copies/mL (c/mL) and CD4+ count >/= 100 cells/mm3 were randomized (1:1) to receive abacavir sulfate/lamivudine/zidovudine (ABC/3TC/ZDV) twice-daily or atazanavir (ATV) once-daily plus lamivudine/zidovudine (3TC/ZDV) twice-daily. Protocol-defined virologic failure was based on multiple failure criteria.Non-inferiority of ABC/3TC/ZDV to ATV+3TC/ZDV was established with 62% vs. 59% of subjects achieving a VL < 50 c/mL at week 48, [ITT(E), M/S = F, 95% CI: -5.9, 10.4]. Similar results were observed in the 230 (82%) subjects with baseline VL<100,000 c/mL (ABC/3TC/ZDV vs. ATV+3TC/ZDV), 66% vs. 59%; 95% CI: -5.6, 19.5. However, ABC/3TC/ZDV did not meet the non-inferiority criterion compared to ATV+3TC/ZDV in the 48 subjects with baseline VL >/= 100,000 c/mL, 39% vs. 60%; 95% CI: -49.2, 7.4, respectively. Protocol-defined virologic failure was similar between groups.

Conclusion: ABC/3TC/ZDV demonstrated comparable virologic efficacy to ATV+3TC/ZDV in this population over 48 weeks. In those with a baseline VL >/= 100,000 c/mL, subjects in the ATV+3TC/ZDV showed better virologic efficacy. Both regimens offer benefits in select therapy-naïve subjects.

Trial Registration: [Clinical Trials Identifier, NCT00082394].