October 26, 1999
This study enrolled 101 participants, with an average viral load of 100,000, and CD4 count of 156 cells. This group had taken an average of three prior protease inhibitors, and four prior nucleoside antivirals. About 40% had taken a nonnucleoside before, but about 60% had never taken a medication in that class. The results were presented exploring the impact of using a nonnucleoside for the first time in this combination, as well as the difference in seeing viral suppression for those who had an initial viral load either below or above 40,000 at the time of the switch.
The combination was fairly well tolerated. About 16% discontinued this combination by week 16, with most of this due to adverse side effects. An additional nine participants discontinued just the abacavir due to suspected hypersensitivity reaction but otherwise stayed in this study by substituting other medications.
At week 16, the overall success rate in getting to below 400 copies was 25%. For those with a viral load below 40,000, it was 41%, while for those over 40,000 it was only 16%. For those who were using their first nonnucleoside, the results were that 35% achieved a viral load below 400 copies, while only 10% of those with prior nonnucleoside use achieved that level of suppression. The follow up at 48 weeks showed that all but two participants who initially went below 400 copies by week 16 were able to stay there, although the protocol did allow other medications to be added after 16 weeks to maintain viral suppression.
For those with a lower viral load and who have never taken a nonnucleoside, this combination represents one available option for a next chance at viral suppression. Other analyses of these data suggested that resistance testing may allow even better precision in deciding who would benefit from using this combination.