Phase 1 Study to Investigate ABS-101 in Healthy Adult Participants

This study evaluates the single-dose administration of ABS-101 or matched placebo, administered subcutaneously (SC) at 4 dose levels (150, 300, 600 and 1000 mg) and intravenously (IV) at 1 dose level at 300 mg which will be in parallel with the 1000 mg SC dose.. Each cohort will consist of 8 participants who will each receive a single dose of investigational drug or matched placebo. Healthy volunteers will stay in the clinical research unit for a period of 4 days in total, including admission on the day before dosing, and 3 days observation following administration of study intervention. Each of the cohorts will be followed-up afterwards for safety. Safety, tolerability, and available PK data will be reviewed by the Safety Review Committee (SRC) for dose escalation by evaluating adverse events and laboratory values.

The SAD portion of the study evaluates the single-dose administration of ABS-101 or matched placebo, administered subcutaneously (SC) at 4 dose levels (150, 300, 600 and 1000 mg) and intravenously (IV) at 1 dose level at 300 mg which will be in parallel with the 1000 mg SC dose. Each SAD cohort will consist of 8 participants who will each receive a single dose of investigational drug or matched placebo. Healthy volunteers will stay in the clinical research unit for a period of 4 days in total, including admission on the day before dosing, and 3 days observation following administration of study intervention. Each of the cohorts will be followed-up afterwards for safety. In the MD portion, 8 eligible participants will be enrolled in a single cohort to receive ABS-101 administered IV, randomized to ABS-101 or placebo. Sentinel dosing will be implemented in this cohort to enhance participant safety. Participants will be admitted to the CRU on the day prior to dosing (Day –1, Day 21, and Day 42) and will receive three consecutive IV doses of either ABS-101 or placebo every 3 weeks. They will remain in-house for a total of 4 days following each dosing and will then return for outpatient visits to undergo safety, tolerability, PK, PD, and immunogenicity assessments before the next scheduled dosing visit. The MD part will be initiated following Safety Review Committee (SRC) evaluation of SAD cohorts 4 and 5. The MD cohort will start with a dose of 600 mg IV. Optional SAD cohorts are also included in the design: the first optional cohort is planned to investigate 50 mg administered SC vs placebo after completion of the non-optional SAD cohorts, and a second optional cohort will be initiated after the first MD dosing to investigate a higher single IV dose of 1200 mg vs placebo. Safety, tolerability, and available PK data will be reviewed by the Safety Review Committee (SRC) for dose escalation by evaluating adverse events and laboratory values.