317   Efficacy and Safety of Switch to 3TC 300 mg QD vs. Continued 3TC 150 mg BID in Subjects with Virologic Suppression on Stable 3TC/d4T/ PI Therapy (COLA4005): Final 24- Week Results.

M. Sension*¹, N. Bellos², J. Johnson³, G. Sepulveda⁴, J. Santana⁵, M. Ames³, and D. Goodwin³.
¹North Broward Hosp. District, Ft. Lauderdale, FL;²Southwest ID Assoc., Dallas, TX;³Glaxo Wellcome, Res. Triangle Park, NC;⁴Hosp. Reg. de Ponce, PR; and⁵San Juan AIDS Project, PR.

Background:Once-daily dosing of one or more antiretroviral medications may promote successful therapeutic outcomes and simplify HIV treatment regimens.

Methods:This 24-week, prospective, randomized (1:1), multicenter trial compared the efficacy (sustained virologic suppression) and safety/tolerability of a switch to 3TC 300 mg QD vs. continued standard dosing of 3TC 150 mg BID in subjects with virologic suppression (HIV RNA <400 c/mL>3 months) on stable (>6 months) therapy with 3TC 150 mg BID, plus d4T and either indinavir (IDV) or nelfinavir (NFV). Subjects (>18 years, CD4 counts>50/mm³) continued stable regimens of d4T plus either IDV or NFV in combination with randomized 3TC regimens.

Results:81 subjects (86% male) received>1 dose of study drug. 78 subjects completed the study. Median entry HIV RNA (VL) was <50 copies/mL in both groups; median CD4 counts were 514/mm³(QD) and 532/mm³(BID). 75% of subjects had been on their pre-trial enrollment regimens for >1 year, and 56% had been on them for >1.5 years. A high rate of virologic suppression was sustained through 24 weeks by both regimens (QD: 95% <400 c/mL; BID: 90%; ITT, M = F; p = 0.679). At week 24, 82% of subjects on QD regimen had VL <50 c/mL, vs 81% on BID regimen (ITT, M = F, p = 1.00). No virologic failure (defined as>1265 copies/mL on 2 separate occasions>2—4 weeks apart), disease progression, or death occurred. CD4 increases were similar for both dosing regimens (median increase: 42/mm³

QD; 22/mm³, BID). Both dosing regimens were well tolerated; safety profiles were generally comparable. No drug-related serious adverse events were reported.

Conclusions:A high rate of virologic suppression was sustained through 24 weeks of treatment with triple HAART regimens containing either 3TC 300 mg QD or 3TC 150 mg BID. These data support the dosing flexibility of 3TC in triple-combination HIV treatment regimens.