A Clinical Study to Evaluate SM17 in Healthy Participants

This Phase I study will be conducted in Chinese healthy adult participants to evaluate the safety, tolerability, PK, and immunogenicity of SM17 SC. This study plans to enroll a total of 30 healthy participants across 4 cohorts, among which three cohorts (n = 8 per cohort) will receive SM17 via subcutaneous injection (SC cohorts), and one cohort (n = 6) will receive SM17 via intravenous injection (IV cohort). SM17 SC cohorts: This part is a randomized, double-blind, placebo-controlled, single ascending dose (SAD) study. A total of 24 healthy participants will be enrolled into three SC cohorts (A1 to A3), with dose levels of 195 mg, 390 mg, and 780 mg, respectively. Each cohort will enroll 8 healthy participants. Each participant will receive a single SC dose of either SM17 (n = 6) or placebo (n = 2). SM17 IV cohort: This part is an open-label, single-dose study. Six healthy participants will be enrolled in a single IV cohort (Cohort B) and will each receive a single intravenous injection of SM17 at a dose of 390 mg. The SM17 SC A2 cohort and SM17 IV cohort (Cohort B) will be enrolled in parallel, and participants will be randomized to one of the two cohorts. A dedicated Safety Review Committee (SRC) will be established for this study. The SRC is responsible for deciding whether to proceed to the next dose cohort based on a review of all relevant safety data from participants at the current dose level for at least 7 days after dosing.