• Simplified Maintenance Therapy with Abacavir + Lamivudine + Zidovudine in Patients with HAART-Induced Long-Term Suppression of HIV-1 RNA: Final Results
  Slide Session 476
  Authored by M. Opravil, B. Hirschel, A. Lazzarin, J. P. Chave, H. Furrer, P. Vernazza, E. Bernasconi, M. Battegay, S. Yerly, C. Python, L. Perrin

Switches have become popular in the last two years. The reasons to switch a successful antiretroviral regimen vary, but the most frequent ones are the wish to simplify the regimen and to prevent or treat the frequent metabolic side effects associated with potent antiretroviral therapy. This study is a well-designed trial in which 163 patients with no evidence of AZT resistance (absence of mutation 215 sequencing the DNA in peripheral mononuclear cells) were randomized to continue their antiretroviral regimen (79 patients) or switch to AZT + 3TC + Abacavir (84 patients). After a year, there were five virologic failures among the patients who continued the protease regimen and 11 among the patients who "simplified" the regimen. Although the difference is not statistically significant (p = 0.06), the trend is worrisome. The tolerability of the switched regimen was better than the original protease inhibitor (PI) regimen.

There were significant improvements in the cholesterol levels as well as in the triglyceride levels (just a trend). In spite of those metabolic improvements this particular switch appears to be less virologically safe than other reported switches to nevirapine or efavirenz (which also show improvements in metabolic parameters). Previous experience with nucleoside analog therapy was associated with an increased risk of virologic failure, among the 69 patients with previous AZT experience there were 9 out of 31 failures in the abacavir arm and 4 out of 38 in the continuing protease arm. In the patients with no AZT experience 1 out of 41 failed if they continued the PI and 4 out of 53 failed if they switched to abacavir. This confirms that the ideal candidate for an antiretroviral "switch" is the patient on his or her first potent antiretroviral regimen and with no previous failure.