Company Decision.

The purpose of this study is to determine the safety and tolerability of imvotamab in patients with severe systemic lupus erythematosus who have failed prior therapies.

Participants will be given imvotamab through a vein (i.e., intravenously).

This is a Phase 1b, randomized, placebo-controlled, multicenter study to determine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of imvotamab in adult participants with systemic lupus erythematosus (SLE). Approximately 18 participants will be assigned to different sequentially dose escalation cohorts.

Key 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.

Key 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.