Ibalizumab Plus Optimized Background Regimen in Treatment-Experienced Patients With Multi-Drug Resistant HIV-1

Inclusion Criteria: (Cohort 1) * Currently receiving ibalizumab via other TaiMed-sponsored or investigator-Sponsored protocol * Are capable of understanding and have voluntarily signed the informed consent document (Cohort 2) * 18 years of age or older * Are capable of understanding and have voluntarily signed the informed consent document * Have documented HIV-1 infection by official, signed, written history (e.g., laboratory report), otherwise an HIV-antibody test will be performed * Are able and willing to comply with all protocol requirements and procedures * Have a viral load \>1,000 copies/mL and documented resistance to at least one antiretroviral medication from each of three classes of antiretroviral medications as measured by previous viral resistance testing (resistance testing is not provided by the study for qualification purposes) * Have a history of at least 6 months on antiretroviral treatment * Are receiving a failing antiretroviral regimen OR have failed and are off therapy * Have viral sensitivity/susceptibility to at least one antiretroviral agent, other than ibalizumab, as determined by previous resistance test performed within 6 months of screening and be willing and able to be treated with at least one agent to which the patient's viral isolate is fully sensitive/susceptible according to the resistance tests used for screening as a component of OBR * If sexually active, are willing to use an effective method of contraception during the study and for…