A Study to Investigate the Safety, Pharmacokinetics, and Pharmacodynamics of VIS954 in Healthy Adult Participants

The study will be conducted in 6 sequential cohorts. Each cohort will enroll 9 participants, randomized to VIS954 or placebo at a ratio of 7:2.

On Day 1, a single dose of VIS954 or placebo will be administered SC. Sentinel participants will be utilized in each cohort. After 14 days, the safety data will be evaluated and a decision to admit and dose the next cohort will be made.

The total duration of the clinical study per participant will be up to 102 days (approximately 4 months).

Inclusion criteria

• Male or female participant between 18 to 55 years of age, inclusive, at the screening visit.
• Non-Japanese participant: Participant does not meet the criteria specified below for 'Japanese Participant'.
• Japanese participant: Participant is of Japanese descent as evidenced by verbal confirmation of familial heritage (a participant's 4 grandparents were born in Japan and recognized to be 'Japanese').
• Body mass index between 18.0 and 30.0 kg/m2, inclusive, at the screening visit.
• Total body weight between 50.0 and 120.0 kg, inclusive, at the screening visit.
• Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and the protocol.
• Willing and able to participate in the study for the defined duration of the study.
• Female participants will be nonpregnant, nonlactating, and either postmenopausal for at least 1 year or surgically sterile for at least 3 months, or will agree to use highly effective methods of contraception from the period prior to study enrollment until 30 days after Day 56; women of childbearing potential must have a negative serum beta-human chorionic gonadotropin (β-hCG) test at screening and a negative urine pregnancy test at baseline prior to administration of the study intervention.
• Male participants with female partners of childbearing potential must agree to use double barrier contraception or abstain from sex during the study and until 90 days after Day 56. Male participants must agree to refrain from sperm donation for the duration of the study and until 90 days after Day 56. This criterion may be waived for male participants who have had a vasectomy greater than 6 months prior to enrollment.
• Healthy, as determined by prestudy medical evaluation (medical history, physical examination, vital signs, 12-lead ECG, and clinical laboratory evaluations), as judged by the principal investigator.

Exclusion criteria

• Participant has a history or current evidence of a serious and/or unstable cardiovascular, respiratory, gastrointestinal, hematologic, autoimmune, blood dyscrasias or other medical disorder, including psychiatric disorders, cirrhosis, or malignancy. History of minor skin cancers (not including melanoma) or surgically treated, limited cervical carcinomas (ie, carcinoma in situ) are not exclusionary.
• Participant is participating in another clinical study of any investigational drug, device, or intervention or has received any investigational medication during the last 30 days or 5 half-lives, whichever is longer, before baseline (Day -1).
• Previous receipt of antibody or biologic therapy.
• History of a previous hypersensitivity or severe allergic reaction with generalized urticaria, angioedema, or anaphylaxis to any of the ingredients of the VIS954 SC injection formulation.
• Blood pressure > 160/100 mmHg or < 90/50 mmHg (may be repeated once if abnormal), at the screening visit or Day -1.
• History of any infection requiring hospitalization or treatment with antivirals, antibiotics, or systemic antifungals within 3 months prior to screening.
• Received a vaccination, other than COVID-19 vaccination, during the 30 days prior to administration of the first dose of study intervention. A COVID-19 vaccination cannot be received within 7 days prior to the first dose of study intervention and until 14 days after the last dose.
• Has received any prescription or nonprescription (over-the-counter) medication during the last 30 days or 5 half-lives, whichever is longer, preceding baseline (Day -1), with the exception of acetaminophen, ibuprofen, naproxen (or other over-the-counter nonsteroidal anti-inflammatory drugs [NSAID]), hormonal contraceptives, topical medications, vitamins, and dietary or herbal remedies.
• Any participant who has a recent history of alcohol or drug/chemical abuse, at the discretion of the investigator, will be excluded.
• Enrolled participants must abstain from consumption of nicotine containing products from Day -1 through discharge.
• Enrolled participants must abstain from consumption of cannabinoids from Day-1 through end of study.
• For the duration of the study, enrolled male participants should not consume more than 15 standard drinks per week (7 days) and female participants should not consume more than 10 standard drinks per week (7 days). A standard drink equals 10 g of alcohol. Enrolled participants must abstain from consuming alcohol 48 hours prior to check-in on Day -1 through discharge.
• Participant with a positive urine drug or alcohol breath screen test result at screening or Day -1. The urine drug screen and alcohol breath screen may be repeated once at the discretion of the investigator. The urine drug screen also screens for methylenedioxymethamphetamine and propoxyphene. If a participant tests positive on these tests, inclusion of that participant into the study will be based on the principal investigator's judgment with consultation, as needed, with the medical monitor and the sponsor.
• Any chronic infectious disease (eg, chronic urinary tract infection, chronic sinusitis, bronchiectasis, active pulmonary or systemic tuberculosis [TB], chronic viral hepatitis such as hepatitis C or hepatitis B, or human immunodeficiency virus [HIV] infection).
• Participant who has donated > 500 mL of blood within 60 days prior to start of the screening visit or the participant has donated any plasma within 7 days prior to baseline (Day -1).
• Coronavirus disease 2019:

• Current symptoms of infection.
• Diagnosis of COVID-19 (reverse transcription polymerase chain reaction [RT-PCR], antigen testing, or clinical diagnosis) in the 21 days prior to screening.
• Ongoing diagnosis of "Long-COVID" symptoms, due to a prior COVID-19 infection.
• Is an employee of the clinical research team (any sponsor or research site employee), or has a family member who is an employee of these organizations.
• Participant is judged by the investigator or the medical monitor to be inappropriate for the study.