Efficacy, and Safety Study of Optimized Background Antiretroviral Regimen (OB) in Combination With Enfuvirtide in the Treatment-Experienced Participants With Human Immunodeficiency Virus-1 (HIV-1) Infection

Open-label, Randomised and Multi-center Study Evaluating the Efficacy and Safety of an Optimised Background Antiretroviral Regimen (OB) Compared to OB Associated With Enfuvirtide in Previously Treated HIV-1 Infected Patients in Virological Success After a 28-week Induction Treatment With Enfuvirtide Plus OB

This is an open-label, randomized and multi-center study to compare the efficacy and safety of continued enfuvirtide (Fuzeon) plus (+) OB therapy versus OB alone in participants with HIV-1 infection. Participants will receive an initial 28 week induction treatment with enfuvirtide + OB. After 28 weeks participants with a plasma viral load less than or equal to (</=) 400 copies/milliliter (mL) at Week 16 and less than (<) 50 copies/mL at Week 24 will be randomized in the ratio 1:1 to receive either enfuvirtide + OB or OB alone for another 24 weeks (up to Week 52).

Inclusion Criteria:

• Participants with HIV-1 infection
• Female participants without any risk of pregnancy
• Participants previously treated with drugs of 2 or 3 different antiretroviral classes
• Participants currently on highly active antiretroviral treatment (HAART) for more than 4 weeks and with a plasma viral load between 1,000 and 300,000 copies of HIV-1 ribonucleic acid per milliliter (RNA/mL)
• Participants with the possibility of potentially effective OB without enfuvirtide, consisting to 2 to 5 drugs, at least two of which are active from at least two different antiretroviral classes
• Cluster of differentiation 4 (CD4) cell count greater than (>) 50 cells/cubic millimeter (mm^3) at screening
• Participants in whom resistance mutations have been detected in reverse transcriptase and/or protease genes
• Enfuvirtide-naive participants

Exclusion Criteria:

• Women of childbearing age not using effective mechanical contraception
• Pregnant or breastfeeding women
• Presence of HIV-2 coinfection
• Participants participating or having participated to another clinical trial during the 30 days prior to selection for this trial
• Participants having previously been treated with enfuvirtide
• Presence active opportunistic infection within 1 month of study entry
• Existence of Grade 4 clinical or laboratory abnormalities
• Cirrhosis or severe hepatic failure
• Uncontrolled diabetes or requiring insulin
• Consumption of alcohol and/or narcotics and/or other substances