Inclusion Criteria:  Signed Informed Consent Form For adolescent patients: Informed Consent Form for study participation signed by the parents or a legal guardian, and patient assent obtained, as per local requirements Ability to comply with the study protocol procedures Confirmed diagnosis of gMG (anti-AChR, anti-MuSK or anti-LRP4 present at screening) A total MG-ADL score of ≥ 5 points at screening with more than 50% of this score attributed to non-ocular items MGFA severity Class II-IV Ongoing gMG treatment at a stable dose For female patients of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use adequate contraception during the treatment period and for at least 3 months after the final dose of satralizumab.  Exclusion Criteria:  History of thymectomy within 12 months prior to screening Ocular MG (MGFA Class I) and myasthenic crisis (MGFA Class V) within the last 3 months prior to screening Known disease other than gMG that would interfere with the course and conduct of the study Positive screening tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) Evidence of latent or active tuberculosis (excluding patients receiving chemoprophylaxis for latent tuberculosis infection) Receipt of live or live attenuated vaccine within 6 weeks prior to baseline Pregnant or breastfeeding, or intending to become pregnant during the study or within 3 months after the last dose