About The Study

Compare a combination of three reverse transcriptase inhibitors with a combination of two reverse transcriptase inhibitors and a protease inhibitor. Test the hypothesis that the two treatments are equivalent based upon proportions of volunteers with viral loads below 400 copies/ml at 48 weeks.

Study Approach

This was a Phase III, randomized, double-blind, parallel group, international multicentre study. Antiretroviral-naïve volunteers with viral loads above 10,000 copies/ml and CD4 counts above 100 cells/mm3 were randomized to receive either abacavir (1592U89) plus indinavir placebo or indinavir plus abacavir placebo, in combination with CombivirTM (3TC 150 mg plus AZT 300 mg). The study looked at volunteers with viral loads above 100,000 copies/ml and below 100,000 copies/ml separately. After week 16, volunteers with viral loads above 400 copies/ml on two consecutive occasions could switch to open label therapy.

Study population

The study included 562 participants who were enrolled between August 1997 and June 1998. At the onset, the median viral load was 70,795 copies/ml in the abacavir group and 66,069 copies/ml in the indinavir group. In the abacavir group, 64 percent had viral loads between 10,000 – 100,000 copies/ml and 63 percent in the indinavir group. Approximately one third of participants had viral loads greater than 100 000 copies/ml. CD4 counts medians were 359 and 360 in the abacavir group and the indinavir group respectively.


Abacavir/Combivir demonstrated an equivalent virological response to indinavir/Combivir based upon the proportion of volunteers with viral load below 400 copies/ml at 48 weeks. Increases in CD4 counts were comparable between treatments. The treatments were comparable for volunteers with viral loads below 100,000 copies/ml. For volunteers with viral loads above 100,000 copies/ml, a difference in favour of indinavir/Combivir was observed using the below-50 assay. Adverse events leading to treatment discontinuation were similar in both treatment groups.


In this study of antiretroviral-naïve, HIV-infected adults, the triple-nucleoside regimen of abacavir-lamivudine-zidovudine was equivalent to the regimen of indinavir-lamivudine-zidovudine in achieving a viral load level of less than 400 copies/ml at 48 weeks.

Note: These results were taken from an article published in JAMA, 7 March 2001, Vol. 285, No. 9.