• Long-Term Virologic and Immune Responses in Subjects Maintained on Exclusive Nucleoside Analog (NRTI)-Based Therapy in ACTG 364 (Poster 322)
  Authored by M. Albrecht, S. Hammer, S. Liou, R. Bosch, and D. Katzenstein
  View the original abstract

We try to use as few agents as possible to suppress HIV in order to preserve agents for future use and limit toxicity. Current thought involves the use of three or more agents to target different reproductive aspects of HIV and balance toxicities, three similar agents such as Trizivir (composed of three NRTIs: AZT, 3TC, abacavir), or various combinations of these components. Certain patients were started on two NRTIs before these other agents were available and had viral suppression and stable CD4 counts. They were then presented with the clinical question, if it ain't broke, why fix it? The devil's advocate said that there was an increased statistical chance of failure with a two-drug regimen, so fix it before it breaks. This study done by the AIDS Clinical Trial Group, the largest NIH-funded network, examined this question by studying patients who had been on two NRTIs for close to five years, had prevailed through a trial that had failed, and were clinically stable.

These 41 patients who had viral loads <500 and median CD4 counts of 568 were then followed for an additional 40-48 weeks with the understanding that they would be given nelfinavir, efavirenz, and new NRTI if they failed. How many remained stable after five years of stability? 59% continued to have RNA <50 copies/mL. This could be predicted somewhat by the baseline viral loads on entry into the new trial, as 77% of the patients on entry who had lower viral loads with at least one value below 50 maintained this virological stability. None of the nine patients whose viral loads wavered between 50 and 500 copies achieved this increased stability. These patients also maintained stable CD4 counts.

This study is actually of limited value to me, although it helps me understand that the patients who are stable and have viral loads <50 copies/mL will probably maintain stability and the higher viral loads. I am trying hard to think of a common clinical problem this study is answering and I find that it just doesn't answer any. Patients who are stable with superb viral control can stay on any regimen they are on if it is not toxic and effective. I feel slightly reassured to see that, but I think we all knew that already.