The purpose of this study is to assess the safety, tolerability, PK, PD, immunogenicity, and preliminary clinical activity of Cizutamig in patients with Systemic Lupus Erythematosus

This is a Phase 1b, open-label, multicenter study evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary clinical activity of cizutamig in patients with Systemic Lupus Erythematosus

Inclusion Criteria:

1. 18 to 75 years old at the time of signing the informed consent form
2. Diagnosis of SLE according to the ACR/EULAR classification criteria
3. Positive anti-dsDNA or positive anti-Smith antibodies AND positive for at least one other of anti-dsDNA, anti-Smith antibodies, or ANA ≥1:80 at screening
4. SLEDAI-2K total score ≥6 and SLEDAI-2K clinical score≥4 at Screening
5. The investigator judged that the patient had an inadequate response to prior treatment for at least 3 months before screening
6. Stable use of concomitant therapies
7. For patients with active LN only: LN Class III or IV

Exclusion Criteria:

1. Inadequate clinical laboratory parameters at Screening
2. Active infection
3. Receipt of or inability to discontinue any excluded therapies
4. Receipt of live vaccine within 4 weeks prior to Screening
5. Presence of any concomitant autoimmune disease
6. Active or known history of catastrophic anti-phospholipid syndrome (APS)
7. APS or thrombotic event not adequately controlled by anticoagulation therapy
8. History of progressive multifocal leukoencephalopathy
9. History of primary immunodeficiency or a hereditary deficiency of the complement system
10. Central nervous system disease
11. Presence of 1 or more significant concurrent medical conditions
12. Have a diagnosis or history of malignant disease within 5 years
13. Serious mental illness, alcohol or drug abuse, dementia, or any other condition that would impair the patient's ability to receive the planned treatment or to understand informed consent at the study site as determined by local practice
14. Inability to comply with protocol-mandated requirements
15. History of severe allergic or anaphylactic reactions to mAb therapy (or recombinant antibody-related fusion proteins) or any constituents of cizutamig
16. History of or planned organ transplant and/or autologous or allogeneic hematopoietic stem cell transplantation
17. Major surgery requiring use of general anesthesia within 12 weeks or planned or expected major surgery during the study
18. Women who are pregnant or breastfeeding
19. Patients who do not agree to the use of highly effective contraception as defined by the protocol
20. Individuals considered to be part of a vulnerable population (eg, incarceration)