To Evaluate the Efficacy and Safety of Genalumab for Injection in the Treatment of Active Systemic Juvenile Idiopathic Arthritis.

Inclusion Criteria: Male and female patients, with the remaining before age 2 years old or more and & lt; 18 years old; 2001 ILAR classification criteria for the diagnosis of confirmed sJIA 2 or more months: onset age must & lt; At 16 years of age, symptoms included: ≥1 case of arthritis, accompanied by or prior to ≥2 weeks of recurrent fever, including remittenor fever for ≥3 consecutive days (maximum daily body temperature ≥39 ° C, body temperature falling below 37 ° C between 2 heat peaks), accompanied by at least one of the following symptoms: ① a transient, non-fixed erythematous rash; ② systemic lymph node enlargement; Swelling of the liver and/or spleen; ④ Serositis. Agree to use effective means of contraception throughout the study period and for 6 months after the end of treatment. Exclusion Criteria: Pregnant or lactating female subjects A history of allergic reactions to investigational drugs or to molecules with similar structures; Those who cannot be given intramuscular injections； History of pericarditis, myocarditis, serositis, bacterial heart valve or endocarditis within 6 months before screening; Patients who had been diagnosed with MAS within 6 months prior to screening, or had relevant symptoms and signs at screening, and were suspected of having MAS as assessed by the investigators； There are other rheumatic diseases such as Kawasaki disease, polyarteritis nodosa and so on. History of autoinflammatory diseases such as familial Mediterranean fever, high IgD syndrome, NLRP3-related autoinflammatory diseases； Patients with a history of interstitial lung disease, pulmonary fibrosis, alveolar proteinosis, or pulmonary hypertension; Patients with a history of repeated invasive fungal infection; In the 7 days prior to randomization, there were infections that required control with systemic antigenic microbiotics (including antibacterial, antiviral, antifungal, etc.)； Subjects with a history of TB exposure or suspected TB symptoms.