7th Conference - Abstract 525

Continued Lamivudine (3TC) vs. Delavirdine (DLV) in Combination with Indinavir (IDV) and Zidovudine (ZDV) or Stavudine (d4T) in 3TC-Experienced Patients: 48-Week Follow-Up of ACTG 370

D. R. KURITZKES*, R. L. BASSETT, V. A. JOHNSON, I. C. MARSCHNER, J. J. ERON, K. WOOD, J. P. SOMMADOSSI, and C. B. PETTINELLI for the Adult ACTG 370 Study Team. Univ. of Colorado Hlth. Sci. Ctr., Denver; Harvard Sch. of Publ. Hlth., Boston, MA; Univ. of Alabama, Birmingham; Univ. of North Carolina, Chapel Hill; FSTRF, Amherst, NY; and DAIDS/NIAID, Bethesda, MD

Sixty-three patients who had received combination NRTI therapy with d4T or ddI plus 3TC and had plasma HIV-1 RNA >500 copies/mL were randomized to ZDV/3TC/IDV vs ZDV/DLV/IDV. Primary analysis at week 20/24 (intention-to-treat, missing=failure) suggested a trend in favor of the ZDV/DLV/IDV arm. Plasma HIV-1 RNA was <200 copies/mL in 22/30 (73%) subjects randomized to ZDV/DLV/IDV vs 19/33 (58%) on ZDV/3TC/IDV(p=0.29). Continued follow-up demonstrated that this trend became significant at week 48: plasma HIV-1 RNA levels were <200 copies/mL in 25/30 (83%) patients in the ZDV/DLV/IDV arm vs 16/33 (48%) in the ZDV/3TC/IDV arm (P=0.007). Week 48 plasma HIV-1 RNA was <50 copies/mL in 23/30 (77%) in the ZDV/DLV/ IDV arm vs 13/33 (39%) in the ZDV/3TC/IDV arm (p=0.005). Kaplan-Meier analysis of time-to-failure likewise favored the ZDV/ DLV/IDV vs ZDV/3TC/IDV (p=0.05 for probability of remaining <200 copies/mL or <50 copies/mL). Patients previously treated with ZDV/3TC who had RNA >500 copies/mL received d4T/DLV/IDV in this study. 22/40 (55%) had plasma HIV-1 RNA levels <200 copies/mL (48% with <50 copies/mL) at week 48. Mean CD4 counts increased by 120-145 cells/mL from baseline to week 48 with no significant difference between arms. These results suggest that it is better to replace both NRTIs with two new RTIs when adding a PI to patients with a history of dual-NRTI therapy.

Key Words: Antiretroviral drugs, NNRTI's, Protease Inhibitors