404   Treatment of Primary HIV Infection: Efficacy, Tolerance, and Predictors of Response.

A. Kurup* and S. Little.
Univ. of California, San Diego.

Background:To realize the potential benefits of antiretroviral therapy in primary HIV infection, effective and tolerable regimens are required.

Methods:We evaluated 48 subjects enrolled in the San Diego Primary Infection Program (mean follow-up 532 days) who initiated therapy (regimens with PI = 32, NNRTI = 7, both = 9) a mean of 62 days after study entry. Retrospective antiretroviral susceptibility testing (ViroLogic) was performed. All subjects received extensive educational and social support services. Baseline CD4 and HIV RNA were studied as predictors of response at weeks 24 and 48.

Results:Twenty-nine subjects (60%) changed therapy 61 times, utilizing a mean of 5 different drugs (mean 3 different regimens/year). The mean HIV RNA at the time of treatment changes was 3 log₁₀copies/ml. Clinical and laboratory toxicities and virologic failure resulted in 43% of treatment changes. Subjective intolerances resulted in 56% of treatment changes. Complete virological suppression (HIV RNA <400 copies/ml) was demonstrated in 32 subjects (66%) during follow-up. Fifty-two percent of subjects achieved virological suppression at week 24 (21% to <50 copies/ml) and 46% of subjects (31% <50 copies/ml) achieved it at week 48. Baseline CD4 and HIV RNA were not significant predictors of virological responses. Four of 14 (29%) subjects with reduced antiretroviral susceptibility (>2.5 fold) at baseline experienced virological failure (lack of suppression or relapse) compared to 1 of 34 subjects (3%) with wild type virus (p = 0.02, OR = 13.2). A greater number of antiretroviral drugs was utilized by subjects whose virus showed reduced antiretroviral susceptibility at baseline compared to subjects with susceptible virus (5 vs 3 drugs respectively) (p = 0.09).

Conclusions:Suboptimal treatment responses were observed in this closely supervised and well-supported patient cohort as a result of frequent toxicities, intolerances and regimen changes. Treatment-limiting adverse experiences may limit both virologic efficacy and future therapeutic options. Baseline resistance testing may improve outcomes.