Ibalizumab Plus Optimized Background Regimen in Patient With Multi-Drug Resistant HIV

This Phase 3, single arm, multicenter study will evaluate the safety and effectiveness of ibalizumab in treatment-experienced patients infected with multi-drug resistant HIV-1. Patients must have been treated with HAART for at least 6 months and be failing or have recently failed (i.e., in the last 8 weeks) therapy to determine baseline viral load. Days 0-6 of the study will be a "control period." During Days 0 through 6 patients will be monitored on current failing therapy (or no therapy, if the patient has failed and discontinued treatment within the 8 weeks preceding Screening). Days 7-13 of the study will be an "essential monotherapy period." During Days 7 through 13 patients will continue on current failing therapy and receive one 2000 mg dose (loading dose) of ibalizumab on Day 7. Day 7 is Baseline for the treatment period (Day 7-Week 25). Day 14-Week 25 of the study will be the "maintenance period." On Day 14 (primary endpoint), the OBR will be initiated and must include at least one agent to which the patient's virus is susceptible. Beginning at Day 21, 800 mg of ibalizumab will be administered every 2 weeks through Week 23. End of Study evaluations will be performed at Week 25, and a follow-up visit will be conducted at Week 29.