566 - Abstract (11th CROI)

Session 81 Poster Abstracts
Antiretroviral Treatment Strategies
Monday, 1:30 - 3:30 pm
Poster Hall

566
Safety and Efficacy of a QD Simplification Regimen
A Barrios*¹, E Negredo², J Vilaró-Rodríguez³, P Domingo³, V Estrada⁴, P Labarga⁵, V Asensi⁶, D Morales⁷, J Santos⁸, J Terrón⁹, E Casas¹⁰, M Riera¹¹, A Vergara¹², J Gonzalez-Lahoz¹, V Soriano¹, and ddI+TDF+EFV Spanish Study Group
¹Hosp. Carlos III, Madrid, Spain; ²Hosp. Germans Trias i Pujol, Barcelona, Spain; ³Hosp. Sant Pau, Barcelona, Spain; ⁴Hosp. Clin. San Carlos, Madrid, Spain; ⁵Hosp. de San Millán, Logroño, Spain; ⁶Asturias Central Hosp., Oviedo, Spain; ⁷Hosp. Virgen de la Macarena, Sevilla, Spain; ⁸Hosp. Virgen de la Victoria, Málaga, Spain; ⁹Hosp. de Jerez, Cádiz, Spain; ¹⁰Hosp. Príncipe de Asturias, Madrid, Spain; ¹¹Hosp. Son Dureta, Palma de Mallorca, Spain; and ¹²Hosp. de Puerto Real, Cádiz, Spain

Background: TDF, ddI, and EFV are all prescribed once daily and show high genetic barrier to resistance, which make them ideal for simplification strategies. However, concern exists about ddI and TDF interactions.

Methods: In a prospective trial conducted in 12 Spanish hospitals, a total of 309 HIV⁺ patients switched prior ARV regimen to TDF+ddI+EFV (QD arm‑didanosine plus tenofovir plus efavirenz).) and 51 subjects continued receiving their prior regimen (control arm). All patients had maintained undetectable viral load for at least 6 months before being recruited in the trial.

Results: Data from 219 and 127 patients in the QD arm at 3 and 6 months, and from 33 and 22 patients, respectively, in the control arm, were assessed. Baseline characteristics did not differ in both treatment arms. In QD arm: mean age, 42 years; male, 80%; mean time on prior ARV, 72 months; prior suboptimal ddI use, 28%; reduced ddI dose (250 mg/day), 30%; mean CD4 count, 607 cells/mL. At 3 and 6 months, viral load <50 copies/mL was maintained in 85% and 86% of patients in the QD arm, and in 97% and 91% of controls (OT analysis)(not statistically different). In the intent-to-treat analysis, these figures were 79% and 64% for the QD arm and 97% and 91% for the controls, respectively (p <0.05). Mean CD4 change was +20 and +26 cells/mL at 3 and 6 months in the QD arm and +2 and +12 cells/ mL, respectively, in controls. Treatment discontinuation occurred in 32 patients (10% of all who switched therapy) in the QD arm and, as expected, in none of controls. However, drop-outs in the QD arm due to virologic failure were seen in only 4 cases, being the remaining mainly due to EFV-related CNS abnormalities. One patient developed possible TDF-kidney dysfunction. Neither cases of pancreatitis nor neuropathy appeared. The lipid profile improved in the QD arm but not in controls.

Lipid Values at 6 Months	TDF+ddI+EFV	Controls	p
% D triglycerides (mg/dL)	- 16%	-2%	NS
% D total cholesterol (mg/dL)	- 9%	-2%	0.04
% D HDL-cholesterol (mg/dL)	+ 1%	-12%	0.04
% D LDL-cholesterol (mg/dL)	- 6%	- 8%	NS
% D total/HDL-cholesterol (mg/dL)	- 8%	+ 13%	0.001

Conclusions: Simplification with daily ddI+TDF+EFV is relatively safe and potent, and improves the lipid profile in patients under successful HAART. Co-administration of TDF and ddI (even at standard doses) does not seem to enhance the risk of ddI toxicities, at least during the first 6 months of therapy.

Keywords: Simplification; Didanosine; Tenofovir

Lipid Values at 6 Months