Study terminated due to tolerability issues.

Overall design: Single-center, randomized, blinded, placebo-controlled single- and multiple-ascending dose study in healthy adult subjects.

This first-time-in-human (FTIH) SAD and MAD studies in healthy adult subjects will be conducted at one site in the United States of America (USA) on IV and SC VIB9600.

Study acquired from Horizon in 2024. Originally Viela Bio was the sponsor.

Key Inclusion Criteria:

1. Healthy male and female subjects aged 18 through 65 years at the time of consent.
2. Body mass index (BMI) of 19.0 through 35.0 kg/m2 at screening and minimum weight of 50 kg.
3. Females must have been surgically sterilized.
4. Nonsterilized male subjects who are sexually active with a female partner of childbearing potential must use a male condom with spermicide from Day 1 through to the final follow-up visit.
5. Able and willing to comply with the requirements of the protocol.

Key Exclusion Criteria:

1. Concurrent enrollment in another clinical study involving an investigational treatment.

2. Received administration of an investigational drug or participated in a device trial within 3 months prior to screening (Visit 1).

3. Subject is a participating investigator, sub-investigator, study coordinator, or employee of the participating site, or is a first-degree relative of the aforementioned.

4. History, or a reason to believe that a subject has a history, of drug or alcohol abuse within the 2 years prior to screening.

5. Positive test for drugs of abuse.

6. Donation of blood or blood products in excess of 500 mL within 3 months prior to screening. Not agreeing to refrain from blood or blood product donations during study participation.

7. Receiving any of the prohibited concomitant medications:

   1. Any immunotherapy or immunosuppressive therapy
   2. Chronic use of steroid medications
   3. Immunoglobulin or blood products
   4. Live vaccines
   5. Anticoagulants
   6. Aspirin

Investigator and subject are blinded, sponsor and site pharmacist are unblinded.