Tenofovir/FTC maintains greater virological response and reduced lipoatrophy compared to AZT/3TC after 96 weeks
Simon Collins, HIV i-Base
Joel Gallant and colleagues presented 96-week data from Gileads Phase III study comparing once-daily tenofovir/FTC to fixed dose twice-daily AZT/3TC (Combivir) in treatment naive patients starting on efavirenz-based regimens. 
Results from the primary endpoint (virological response <50 copies/mL at 48 weeks) have already been reported at earlier meetings, and showed advantages in favour of tenofovir/FTC both virologically (driven by higher discontinuations in the AZT/3TC group) and with reduced side effects. The 96-week data reported in Toronto maintained similar differences between the two groups, and included results from DEXA scans at week 96.
Baseline characteristics in the study (ITT, n=509) were similar between arms (median age 37, 14% female, 59% Caucasian, median viral load 5.0 copies/mL, median CD4 237 cells/mm3). Excluding patients (n=22) with baseline NNRTI mutations, 76% in TDF+FTC arm (n=244) vs 64% in CBV arm (n=243) achieved and maintained HIV RNA<400 copies/mL through to week 96 (TLOVR, 95% CI +4.3, +21.1%, p=0.004); 69% in TDF+FTC arm vs. 63% in CBV arm achieved and maintained HIV RNA<50 copies/mL (95% CI -2.0%, 14.7%, p=0.15). The mean increase in CD4 cell count from baseline was significantly greater in TDF+FTC arm (270 vs 237, p=0.036).
Adverse events leading to study regimen discontinuation (most common: anemia, nausea, fatigue, vomiting, rash) were fewer for TDF+FTC arm (5%) vs CBV arm (11%), p<0.001. The renal safety profile was also similar in both arms based on serum creatinineand Cokcroft-Gault GFR (p=0.51), but Glomerular Filtration Rate was significantly slightly lower in the tenofovir/FTC arm (p=0.006).
At week 96 patients in the tenofovir/FTC group had significantly greater increases in weight (2.7kg vs 0.5kg, p<0.001). In a subset of patients with DEXA data, median limb fat at week 96 was greater in TDF+FTC arm (7.7 kg, n=144) compared to CBV arm (5.5 kg, n=136), p<0.001.
In terms of resistance, no patient developed the K65R mutation, and significantly more patients on AZT/3TC developed M184V/I (9 vs 2, p=0.037).
- Gallant J, Pozniak A, DeJesus E et al. Efficacy and safety of tenofovir DF (TDF), emtricitabine (FTC) and efavirenz (EFV) compared to fixed dose zidovudine/lamivudine (CBV) and EFV through 96 weeks in antiretroviral treatment-naive patients. XVI International AIDS Conference, Toronto, Canada. 13-18 August 2006. Poster abstract TUPE0064.