Phase 1, open-label study designed to evaluate safety, tolerability, pharmacokinetic, and pharmacodynamic of multiple doses of BION-1301 in Japanese healthy subjects.

This is a Phase 1 study of BION-1301, a first-in-class humanized IgG4 anti-a proliferation-inducing ligand (APRIL) monoclonal antibody. This is a single-center, open-label study designed to evaluate safety, tolerability, pharmacokinetic, and pharmacodynamic of a single subcutaneous dose of BION-1301 in Japanese healthy subjects in 3 dose level cohorts. The study will enroll up to 36 Japanese subjects across 3 dose level cohorts.

Inclusion Criteria:

• First generation Japanese (confirmed at screening). The definition of first generation is the subject, the subject's biological parents, and the subject's biological grandparents are of exclusively Japanese origin and were born in Japan.
• Body mass index (BMI) between 18 and 30 kg/m^2, inclusive, at screening with a weight of at least 47 kg.
• In good health, as determined by medical history, physical examination, vital signs assessment, 12-lead ECG, and clinical laboratory evaluations within normal reference ranges or outside of normal reference ranges considered not clinically relevant by the investigator
• Female subjects of childbearing potential must have a negative urine or serum pregnancy test, must agree to try to not become pregnant, must agree to consistently use highly effective contraceptive methods, and must agree not to breastfeed or donate ova for a period as defined in the study protocol.
• Male subjects must agree to use highly effective contraceptive methods and must not donate sperm for a period as defined in the study protocol.

Exclusion Criteria:

• Significant history or clinical manifestation of any metabolic, allergic, dermatological, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, neurological, respiratory, endocrine, or psychiatric disorder, as determined by the investigator (or designee).
• History of malignancy during the last 3 years; exceptions include adequately treated basal cell carcinoma and squamous cell carcinoma of the skin
• Confirmed systolic blood pressure >140 or <90 mmHg, diastolic blood pressure >90 or <50 mmHg, and pulse rate >100 or <40 beats per minute at either screening or predose on Day 1.
• Received a live (attenuated) vaccine(s) within 3 months prior to check-in and/or a vaccine(s) that do not contain live microorganism(s) within 14 days prior to check-in.
• Have previously completed or withdrawn from this study or any other study investigating BION-1301, and have previously received BION-1301.
• Positive urine drug screen, alcohol test, or cotinine test at screening or check-in.