Study to Assess Safety, Efficacy and Persistence of ACE1831, in Subjects With IgG4-Related Disease

Inclusion Criteria

• •Signed Informed Consent
• •Male or female ≥ 18 to 75 years of age
• •Active IgG4-RD flare at screening with IgG4-RD Responder Index at least 2, confirmed by symptoms, labs, and/or imaging.
• •History of IgG4-RD involving at least 2 organs/sites, and current flare involves at least 1 organ/site (excluding lymph nodes) requiring treatment.
• •Elevated serum IgG4 above the upper limit of normal at screening.
• •Able to receive glucocorticoids for current flare and taper to 0 mg by Day -5.
• •Contraception agreement per protocol from screening through 24 weeks after last ACE1831 dose (no LDC) or 12 months after last LDC dose (with LDC).
• •For sites in China only: prior treatment failure to glucocorticoids and at least one immunosuppressive agent.