Study to Assess the Safety, Pharmacokinetics and Pharmacodynamics of BOS161721 in Healthy Subjects

Study BOS161721-01 will consist of 7 single ascending dose (SAD) cohorts, each with 8 participants (6 active:2 placebo), and an eighth SAD cohort with 5 participants (all active). Participants will be randomized in a 3:1 ratio (BOS161721:placebo) and will either receive a single dose of BOS161721 (1, 3, 10, 22, 30, 60, 120, or 240 milligrams \[mg\]) or placebo. Participants in Cohort 1 will receive the lowest dose, administered IV (1 mg), followed by Cohort 2, in which participants will receive the second lowest dose, administered SC (3 mg). BOS161721 or placebo will also be administered SC in Cohorts 3, 4, 5, 7, and 8. Participants in Cohort 6 will be administered an IV dose of 22 mg (5 active) in parallel to the 60 mg SC-dosed fifth cohort. This dose has been selected to generate a similar exposure to that following the 30 mg SC dose. The actual Cohort 6 IV dose may be adjusted upon available PK data. Participants will be in this study for up to 56 weeks, which includes a Screening Period of up to 28 days, a single-dose treatment day (during the in-subject treatment period), and a 52-week post-treatment Follow-up Period, which is required due to the potential half-life of BOS161721.