This is a first-in-human, single-center, randomized, double-blind, placebo-controlled, single ascending dose study evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity of a single subcutaneous (SC) or intravenous (IV) administration of STAR-0215 in healthy adult participants.

Inclusion Criteria:

• Good health as determined by the Investigator based upon a medical evaluation, including medical history, physical examination, vital signs, 12-lead electrocardiogram (ECG), and clinical laboratory measurements. Assessments may be repeated per Investigator discretion.
• Body mass index of 18 to 35 kilograms (kg)/square meter with a weight of at least 60 kg for men and at least 50 kg for women, with a maximum weight of 130 kg for any participant.
• Female participants capable of becoming pregnant must have a negative serum pregnancy test at Screening, not be nursing, and must agree to use an effective method of contraception and abstain from egg donation or fertility treatment.
• Male participants must agree to use an effective method of contraception and abstain from sperm donation.

Exclusion Criteria:

• Prior or ongoing medical condition (for example, gastrointestinal, renal, hepatic, dermatological, neurological or psychiatric, cardiovascular, respiratory, or hematological), medical history, physical examination, vital signs, ECG, or clinical laboratory abnormality that, in the Investigator's opinion, could adversely affect the safety of the participant. Assessments may be repeated once prior to dosing as needed per Investigator discretion.
• Known sensitivity to the ingredients in STAR-0215.
• Regular use of prescription or non-prescription drugs unless Investigator believes the medication(s) will not interfere with the study or compromise participant safety.
• Participation in a recent clinical study involving receipt of an investigational product within 30 days prior to the first dose of study drug or exposure to more than 4 investigational products within 12 months prior to the first dose of study drug.