UB-421 in Combination With Optimized Background Regimen in Patients With Multi-drug Resistant HIV-1 Infection

Inclusion Criteria: 1. HIV-1 seropositive 2. Have a history of at least 6 months on antiretroviral treatment 3. Receiving a stable combination antiretroviral therapy (ART) for at least 8 weeks before Screening Exclusion Criteria: 1. Subjects with HBsAg positive or HCV antibody positive, along with ALT or AST \> 4 x upper limit of normal (ULN) 2. Females who are pregnant 3. Any vaccination within 2 weeks prior to the Screening 4. Any prior exposure to UB-421