A Study of Firsekibart Versus Anakinra in Adult-Onset Still's Disease

Inclusion Criteria: * Age: This study will include subjects aged 18 to 75 years (inclusive), regardless of gender. * Subjects must be willing to participate in the study and voluntarily sign an informed consent form. * Diagnosis of AOSD will be based on the Yamaguchi criteria: Major criteria: (1) Fever ≥39°C lasting for ≥1 week; (2) Arthralgia lasting for ≥2 weeks; (3) Typical rash; (4) White blood cell count ≥10×10\^9/L with neutrophils ≥80%. Minor criteria: (1) Sore throat or pharyngitis; (2) Lymphadenopathy and/or splenomegaly; (3) Abnormal liver function; (4) Negative rheumatoid factor and antinuclear antibody. Exclusion criteria: (1) Infectious diseases (especially sepsis and EBV infection); (2) Malignancies (especially lymphoma); (3) Other rheumatic diseases (particularly systemic vasculitis). After excluding the above exclusion criteria, a diagnosis of AOSD requires meeting ≥5 of the above criteria (including at least 2 major criteria). * Active disease is defined as meeting 2 Yamaguchi criteria along with the presence of fever or CRP \>10 mg/L. * If currently receiving glucocorticoid therapy, the dose must have been stable for at least 1 week prior to randomization. The maximum allowed dose is 1 mg/kg/day. * Subjects (including their partners) must have no pregnancy plans from the screening period until 28 days after the last dose and must voluntarily use contraception. Exclusion Criteria: * Pre-randomization Medications: a) Received BTK inhibitors, JAK inhibitors,…