Study to Evaluate Safety, Tolerability, and Pharmacokinetics of UB-621 in Healthy Volunteers

Inclusion Criteria: * With age between 20 and 55 years. * With no clinically relevant abnormalities in vital signs, and clinical laboratory tests at screening visit judged by investigator. * Body weight: \<85 kg. * Subject has signed the written informed consent form. Exclusion Criteria: * With significant active infection (acute or chronic) within 28 days prior to the screening visit. * Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic or allergic diseases, or clinical findings within 3 months prior to the screening visit. * Positive serology for HIV antibody, HCV antibody or HBV surface antigen. * Female subjects who are breastfeeding, pregnant, and planning to become pregnant during the study period. * The clinical investigator considers that the subject is not in the condition to participate in this study.