The safety and efficacy of switching stavudine to tenofovir df in combination with lamivudine and efavirenz in hiv-1-infected patients: three-year follow-up after switching therapy.

Background: Study 903 is a phase 3 trial with a completed 144-week, double-blind phase comparing tenofovir DF (TDF) with stavudine (d4T), in combination with lamivudine (3TC) and efavirenz (EFV), and an ongoing 336-week open-label extension phase.

Method: Patients in 3 countries completing the d4T treatment phase were allowed to switch d4T to TDF and receive once-daily TDF+3TC+EFV in the extension phase.

Results: At the time of switch, 100% and 99% of patients (n = 85; 60% male, 64% White; mean age 37 years; mean CD4 = 650 cells/mm3) had HIV RNA <400 and <50 copies/mL. At 144 weeks after the switch, 89% (missing = failure) had HIV RNA <400 copies/mL and 87% had HIV RNA <50 copies/mL. Mean CD4 cell count increased 155 cells/mm3. No patient had virologic failure. Significant decreases from switch to week 144 in mean fasting total cholesterol (-22 mg/dL, p < .0001) and triglycerides (-78 mg/dL, p < .0001) were observed. Mean limb fat increased significantly from 4.5 kg to 5.8 kg, 144 weeks after switch (p < .0001).

Conclusion: In virologically suppressed patients, switching d4T to TDF as part of a once-daily regimen with 3TC and EFV resulted in maintenance of virologic suppression and continued CD4 cell increases through 144 weeks, with significant improvements in metabolic parameters.