Abacavir vs. Indinavir in Therapy-naive People (CNA3014)

Preliminary 24-week data was presented of an ongoing trial comparing abacavir to indinavir (taken three times a day). Both regimens include Combivir (zidovudine + 3TC). The 342 treatment-naive people in this trial had viral loads above 5,000 copies, and were stratified by viral load -- 5,000 to 100,000, or over 100,000 copies. Thirty-eight percent of people in each group had viral loads over 100,000 copies. CD4 cells at baseline were 323 in the group that received abacavir and 300 in the group that received indinavir.

All of the following results are reported using the intent-to-treat (ITT) analysis. At week 24, of people with baseline viral loads of 5,000 to 100,000 copies, 70% (n=101) of those on abacavir and 58% (n=101) of those on Crixivan had viral loads below 400 copies. Of people who began with baseline viral loads over 100,000 copies, 66% (n=58) of those on abacavir and 54% (n=65) of those on indinavir had viral loads below 400 copies at week 24. When viral loads were measured down to 50 copies at week 24, the percentage of people on abacavir with undetectable viral loads was 68% for those starting with viral loads of 5,000 to 100,000 and 55% for those with baseline viral loads above 100,000. For people on indinavir, at week 24, 53% of those in the low baseline group, and 45% of those in the high baseline group had viral loads below 50 copies.

The average CD4 cell count increase of 110 was the same in both groups. The slightly better results in HIV suppression in the abacavir group were most likely the result of dropouts in the indinavir group due to side effects and lack of adherence. While these results are reassuring, the routine use of non-PI-containing HAART regimens in people with low CD4 counts and/or high viral loads should await longer follow-up from the above, and other, ongoing trials studying this issue.