the Study to Evaluate the Safety of UB-421 in Combination With Antiretroviral Therapy (ART) and the Efficacy in Reduction of HIV Viral Load and Proviral DNA as Compared to ART Alone in ART-experienced Viremic HIV-1 Patients

Inclusion Criteria: 1. HIV-1 seropositive 2. Male with body weight ≥ 50 kg or female with body weight ≥ 45 kg. 3. have been receiving antiretroviral therapy (ART) for more than 2 years Exclusion Criteria: 1. Any previous exposure to a mAb within 12 weeks prior to the first dose of UB-421 treatment. 2. Any significant diseases (other than HIV-1 infection) or clinically significant findings, including psychiatric and behavioral problems, determined during the screening period, medical history, and/or physical examination that, in Investigator's opinion, would preclude the subject from participating in this study. 3. History of anaphylaxis to monoclonal antibodies. 4. Any vaccination within 8 weeks prior to the first dose of UB-421.