Genotypic Resistance Profile in Treatment-experienced HIV Patients After Ziagen (abacavir) and Sustiva (efavirenz) Salvage Regimen

Once HAART fails to suppress HIV replication and resistant viruses emerge, it is difficult to find a salvage regimen since cross-resistance is high among the available classes of antiretroviral drugs.

In this retrospective analysis, genotypic resistance profiles were analyzed in 24 patients who switched treatment to Ziagen (abacavir/ABV), Sustiva (efavirenz/ EFV), and either a NRTI or a PI at baseline and after 24 weeks of treatment.

At baseline, 71% of patients harbored at least one resistance mutation in the protease gene. In the RT gene, 87.5% of the patients showed nucleoside analogue resistance mutations, and an equal 87.5% showed resistance mutations to non-nucleoside analogues.

After 24 weeks of treatment, only mutations to nucleoside analogues appeared in 95.8% of the patients, while resistance mutations to the other drug classes remained constant. Substitutions conferring cross-resistance within each drug family were very common among this treatment-experienced population.

These data also indicate that salvage therapy is likely to remain one of the most important issues in the treatment of HIV infections.

Grupo de Estudio Hepatitis Viricas y SIDA, Edificio de Laboratorios, Seville, Spain.

01/23/04