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SITT: A Prospective Trial of Strategic Treatment Interruptions C. FAGARD1, M. LEBRAZ1, C. TORTAJADA2, F. GARCIA2, E. BERNASCONI3, M. BATTEGAY4, H. GUNTHARD5, H. J. FURRER6, P. VERNAZZA7, A. OXENIUS8, R. PHILLIPS8, S. YERLY1, J. GATELL2, T. PERNEGER1, P. ERB4, L. PERRIN1, and B. HIRSCHEL*1.
1Geneva, Switzerland; 2Barcelona, Spain; 3Lugano, Switzerland; 4Basel, Switzerland; 5Zürich, Switzerland; 6Bern, Switzerland; 7St. Gall, Switzerland; and 8Oxford, UK Background: HIV-specific immune responses (IR) decrease during HAART. Rebounds during treatment (Rx) interruption may stimulate the IR and eventually permit discontinuation of HAART.
Methods: The Swiss Intermittent Treatment Trial (SITT) enrols patients who are ART-naive before HAART, without treatment failure during HAART, with VL < 50 for > 6 months, and nnrti-naive. Rx is stopped for 2 wks, started again for 8 wks, for four cycles. At week 40, Rx is definitely suspended unless VL rebounds > 5000. Endpoints: Amplitude of rebounds, N of pts with VL < 5000 and CD4 > 400 without ART after wk 40.
Results: 57 pts (120 planned) were enrolled between April and September 1999. Before HAART: Median CD4 count 398, median VL 4.56 Logs. Median duration of HAART before SITT was 22 months, and median CD4 at start of SITT was 700. 16 pts have had two Rx stops, and 4 pts have had 3. Viral rebound during the first stop occurred in 28 of 43, and during the second stop in 12 of 16 (P= NS). The second rebound was similar in amplitude to the first rebound (Wilcoxon test, p=0.2). The 4 patients with 3 Rx stops showed rebound to 60000, 30000 and 2700; 12600, 12100, and 728; 1327, 200, and 973; and to < 10, < 10, < 10, during the first, second, and third stop respectively. After 7 weeks re-treatment, 3 of 20 evaluable and compliant pts did not lower their VL to < 50 (VL of 62, 105, and 147). 1 pt had fever and sore throat at the end of the first Rx interruption (VL 925K).
Conclusions: Very early results in the few pts with 3 Rx stops are modestly encouraging. In January 2000, SITT will include at least 50 pts with 2, 30 pts with 3, and 10 pts with 4 Rx stops. Preliminary results from CTL tetramer assays and HIV-specific CD4 helper function will also be available.
Key Words: HAART, immune response, intermittent HAART
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