669   SWATCH Study: A Multicenter Trial of Proactive Treatment Switching. Results at 9 Months of Follow-Up.

E. Negredo*¹, J. Martinez-Picado², L. Ruiz², C. Zala³, K. Hertogs⁴, C. Boucher⁵, R. D'Aquila⁶, B. Clotet^1,2, and The Swatch Study Team.
¹Lluita contra la SIDA Fndn., Barcelona;²IrsiCaixa Fndn., Barcelona, Spain;³Huesped Fndn., Buenos Aires, Argentina;⁴Virco, Mechelen, Belgium;⁵Utrecht Univ, Netherlands; and⁶Massachusetts Gen. Hosp., Boston, MA.

Background:The objective of this study was to compare the clinical, virologic and immunologic response of strategic proactive treatment switching with respect to two standard-of-care regimens among antiretroviral (ART)-naïve patients.

Methods:The SWATCH is an going multicenter international prospective randomized open-label trial that enrolled HIV⁺patients with no restriction in plasma viral load (pVL) or CD4 counts. Patients were randomized to receive stavudine plus didanosine plus efavirenz (arm A) or zidovudine plus lamivudine plus nelfinavir (arm B) or to switch between the two previous arms every three months (arm C). Data collected included determinations of pVL, CD4 cell counts, clinical events, therapy adherence, and quality of life. Genotypic and phenotypic testing was done on patients with virologic failure.

Results:160 patients were enrolled. Baseline characteristics were similar among the three study arms. Median CD4 count was 317 cells/ml, and median pVL was 4.6 logs. To date, 58 patients have reached 9 months of follow- up. Ten patients (5 in group A, 3 in B and 2 in C) were lost to follow-up. 16 subjects switched therapy due to adverse events (3 in group A, 8 in B and 5 in C). Treatment analysis shows that 69%, 89% and 100% of the patients in groups A, B and C, respectively, achieved <400 HIV-1 RNA copies/ml at month 9. Nine patients did not respond to HAART or experienced pVL rebound. Six of them, belonging to arm A, developed resistance to efavirenz; the other 3 patients, belonging to arm B, failed without any evidence of drug resistance. The median CD4⁺increases at month 9 were 122, 93 and 187 cells/ml in groups A, B and C, respectively. However, these differences were not statistically significant. Lipodystrophy was detected in 2 patients (1 in A and 1 in B). Drug adherence was similar in all 3 arms. However, quality of life was estimated to be superior in arm A (p < 0.05).

Conclusions:Preliminary analysis after 9 months of follow-up shows that proactive switching of HAART has a better virologic and immunologic outcome than the other two regimens. Adherence and adverse events were similar in all study groups.