315   Efficacy of Combivir (COM) (Lamivudine 150 mg/ Zidovudine 300 mg) plus Ziagen (Abacavir (ABC) 300mg) BID Compared to Trizivir (TZV) (3TC 150 mg/ZDV 300 mg/ABC 300mg) BID in Patients Receiving Prior COM plus ABC.

M. Fischl*¹, A. Burnside², C. Farthing³, M. Thompson⁴, N. Bellos⁵, V. Williams⁶, and M. Shaefer⁶.
¹Univ. of Miami, FL;²The Burnside Clin., Columbia, SC;³AIDS Healthcare Fndn., Los Angeles, CA;⁴AIDS Res. Consortium, Atlanta, GA;⁵Dallas, TX; and⁶Glaxo Wellcome, Res. Triangle Park, NC.

Background:To demonstrate TZV is not different than COM/ABC as measured by proportion of subjects who maintain HIV-1 RNA (vRNA) levels <50 c/mL and <400 c/mL over 24 wks.

Methods:An open-label randomized study of subjects on prior therapy with COM and ABC BID (>_16 wks), +/ - PI or NNRTI with vRNA<400 c/mL and CD4+ cell count >200/mm³at entry into the study. Subjects were prestratified by use of COM/ABC alone, or with PI or NNRTI. Subjects were randomized to receive either TZV or COM/ABC. Pre-study PI or NNRTI (n=9) was continued if applicable. Subjects were followed for 24 wks or until a study endpoint, defined as vRNA > 0.5 log₁₀above baseline.

Results:Preliminary results (ITT observed) are reported for 186 subjects. Study drug was not started in 3 subjects and discontinued prematurely in 19. The most common reasons for discontinuation were lost to follow- up (n=10) and AE (n=4). Proportion of subjects with vRNA levels <50 and<400 c/mL are given below.

Conclusion:These preliminary 24-wk data suggest that virologic response in subjects switched to Trizivir was not different from that seen with Combivir and Ziagen. Full 24-week data will be presented.