Study of VIB7734 for the Treatment of Moderate to Severely Active SLERECAST SLE

• Age ≥ 18 years to ≤ 70 years • Willing and able to understand and provide written informed consent. • Fulfill the 2019 European League Against Rheumatism/American College of Rheumatology Classification Criteria for SLE • Disease duration of at least 6 months • Active SLE as indicated by presence of all the following: a. SLEDAI-2K total score ≥ 6 at Screening, excluding fever, SLE headache, or organic brain syndrome. b. SLEDAI-2K total score ≥ 4, excluding points attributable to any urine or laboratory results, immunologic measures, fever, SLE headache, or organic brain syndrome at Screening and Baseline (Day 1). c. At least one of the following BILAG 2004 Index levels of disease at Screening: • BILAG A disease in ≥ 1 organ system • BILAG B disease in ≥ 2 organ systems d. PGA score ≥ 1 on a 0 to 3 visual analog scale (VAS) at Screening Have at least one of the following at Screening per central lab: • ANA ≥ 1:80 • Anti-dsDNA antibodies elevated to above normal range as established by the central laboratory (ie, positive results) • Anti-Smith antibodies elevated to above normal (ie, positive results) Ongoing treatment for SLE a. Treatment with one or more disease-modifying anti-rheumatic drug (DMARD) or immunosuppressive medication: Any of the following medications each administered at conventional anti-rheumatic doses for treatment of SLE for at least 12 weeks before Screening (unless discontinued or dose adjusted for documented drug-related toxicity or size/weight), and at a stable dose (including route of administration) for a minimum of 8 weeks prior to Screening and maintained through Baseline (Day 1): b. Treatment with OGC monotherapy (without the concomitant use of DMARDs or immunosuppressants): -Average daily dose of PO prednisone ≥ 10 mg but ≤ 40 mg (or prednisone equivalent) for a minimum of 4 weeks prior to Screening and a stable dose for minimum of 2 weeks prior to Screening. The dose of OGC must be kept for a minimum of 2 weeks prior to Randomization. Daily dosing or alternate day dosing of PO prednisone or equivalent is allowed. • Women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at Randomization. • Non-sterilized male participants who are sexually active with a woman partner of childbearing potential must agree to use a condom with spermicide from Randomization and until 3 months (approximately 5 half-lives) after receipt of the last dose.

• Any condition that, in the opinion of the Investigator, or the Sponsor/Central Review Committee, would interfere with the evaluation of the IP or interpretation of participant safety or study results (including borderline disease activity) • History of allergy, hypersensitivity reaction, or anaphylaxis to any component of the IP or a previous mAb or human Ig therapy • Active LN or active severe or unstable neuropsychiatric SLE • Current diagnosis of non-SLE vasculitis syndrome, mixed connective tissue disease, or rheumatic (overlap) syndrome • Participation in another clinical study with an investigational drug within 4 weeks before Day 1 • Breastfeeding or pregnant women or women who intend to become pregnant anytime from signing the ICF through 6 months after receiving the last dose of IP • Major surgery within 8 weeks prior to Screening or elective surgery planned from Screening through Day 393. • Spontaneous or induced abortion, still or live birth, or pregnancy ≤ 4 weeks before Screening • Known history of a primary immunodeficiency or an underlying condition such as known human immunodeficiency virus (HIV) infection • Hepatitis B, Hepatitis C, active TB, any severe herpes infection, clinically active infection, or opportunistic infection • History of clinically significant cardiac disease including unstable angina; and/or myocardial infarction and/or congestive heart failure within 6 months prior to Randomization. • History of cancer within the past 5 years except, in situ carcinoma of the cervix, cutaneous basal cell or squamous cell carcinoma with curative therapy. • Receipt of a live-attenuated vaccine within 4 weeks before Day 1 Administration of inactivated (killed) vaccines is acceptable • The use of immunosuppressants, biologics and DMARDS within the protocol defined washout periods