The purpose of this study is to assess the safety, tolerability, PK, PD, immunogenicity, and preliminary clinical activity of cizutamig in patients with IgAN.

An Open-Label Study Evaluating the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, Immunogenicity, and Preliminary Clinical Activity of Cizutamig in Patients with Immunoglobulin A Nephropathy

Inclusion Criteria:

• 18 to 75 years of age at the time of signing the informed consent form (ICF).
• Biopsy-confirmed IgAN as specified in the protocol.
• 24-hour urine protein excretion ≥1.0 g/day or 24-hour urine protein to creatinine ratio (uPCR) ≥0.75 g/g .
• Inadequate response to ≥1 of the therapies defined in the protocol.
• eGFR >30 mL/min/1.73m2.

Exclusion Criteria:

• Inadequate clinical laboratory parameters at Screening.
• Receipt of or inability to discontinue any of the following excluded therapies as specified in the protocol.
• Receipt of live vaccine within 4 weeks prior to Screening.
• MEST-C score of T2 from the Oxford IgAN classification schema. If MEST-scoring was not performed, the presence of >50% tubular atrophy/interstitial fibrosis is exclusionary.
• Rapidly progressing glomerulonephritis with eGFR reduction ≥50% within 12 weeks of Screening.
• Secondary IgAN (eg, chronic liver disease, celiac disease, HIV).
• History of IgA vasculitis.
• Presence of any concomitant autoimmune disease .
• History of progressive multifocal leukoencephalopathy.
• History of primary immunodeficiency or a hereditary deficiency of the complement system.
• Central nervous system (CNS) disease .
• Presence of 1 or more significant concurrent medical conditions per investigator judgment.
• Diagnosis or history of malignant disease within 5 years prior to Screening.
• Tonsillectomy within 24 weeks prior to Screening.