This will be a single centre, Phase 1, First-In-Human, Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Ascending Dose of APB-R3 in Healthy Participants.

Primary objective of this study will be to evaluate the safety and tolerability of APB-R3 following intravenous (IV) administration of single ascending dose in healthy participants.

The study will consist of 5 planned cohorts (1 cohort per dose level) for a total of up to 31 participants. Cohorts 1 and 2 will include 5 participants each (3 participants receiving the active and 2 participants receiving the placebo). Cohort 3 to Cohort 5 will include 7 participants each (5 participants receiving the active and 2 participants receiving the placebo).

Inclusion Criteria:

1. Male or female, non-smoker, 18 to 60 years of age (both inclusive),

2. Healthy as defined by:

   1. the absence of clinically significant illness and surgery within 4 weeks prior to study drug administration in the opinion of the investigator.
   2. the absence of clinically significant history of neurological, endocrine, cardiovascular, respiratory, hematological, immunological, psychiatric, gastrointestinal, renal, hepatic, and metabolic disease in the opinion of the investigator.

Exclusion Criteria:

1. Abnormal finding at physical examination
2. Evidence of clinical significant hepatic or renal impairment
3. Clinically significant abnormal laboratory test results or positive serology test results for HBsAg, HCV antibody, or HIV antigen and antibody, or positive test results for COVID-19, or QuantiFERON®-TB test at screening.
4. Any reason which, in the opinion of the Investigator, would prevent the participant from participating in the study.

The study will be double-blinded. The participants and the clinical personnel involved in the collection, monitoring, revision, or evaluation of AEs, or personnel who could have an impact on the outcome of the study will be blinded with respect to the participant's treatment assignment (APB-R3 or placebo).