Inclusion Criteria:

• * Age ≥ 18 years at the time of signing ICF
• * Diagnosis of SLE according to the 2019 European League Against Rheumatism/American College of Rheumatology (ACR) Classification Criteria at least 16 weeks or more prior to screening
• * Highly active SLE disease, as demonstrated by a total systemic lupus erythematosus disease activity index (SLEDAI-2K) total score of ≥ 10 at screening
• * Active SLE disease despite treatment with at least 1 immunosuppressive or biologic standard-of-care agent (e.g., methotrexate, azathioprine, mycophenolate mofetil, belimumab, anifrolumab) determined at the discretion of the investigator after at least 3 months of treatment.
• * It must be planned that the background standard-of-care treatment remains at a stable dose throughout the Screening Period and up to Week 8.

Exclusion Criteria:

• * Pregnant or breastfeeding or intending to become pregnant during the study or within 3 months after the final dose of imvotamab.
• * Any lupus-associated neuropsychiatric disease.
• * Active lupus nephritis with estimated glomerular filtration rate (eGFR) \< 30 mL/min/1.73 m2, calculated according to the Chronic Kidney Disease Epidemiology Collaboration equation, classified as World Health Organization (WHO) Class IV.
• * Prednisone-equivalent \> 30 mg/day, including immediate and extended-release oral formulations.
• * Drug-induced lupus.
• * Participants with a history of catastrophic or severe anti-phospholipid syndrome within 12 months prior to screening.