This study is a phase 3, randomized, double-blind, placebo-controlled study, to be conducted at approximately 100 study sites. Approximately 270 subjects (188 AChR-Ab+ and 82 MuSK-Ab+) will be enrolled. Patients with MG who are positive for anti-AChR or anti-MuSK antibodies will be enrolled and analyzed separately as 2 populations: (1) AChR-Ab+ and (2) MuSK-Ab+. Patients who do not have anti-AChR or anti-MuSK antibodies will not be enrolled. Patients with MGFA classification II, III, or IV disease, MG-ADL score ≥ 6, QMG score ≥ 11, and use of a corticosteroid and/or non-steroidal immunosuppressant will be included in the study.~All subjects who complete the randomized controlled period will have the option to enroll in a 1.5-year open-label period.
Randomized, double-blind, placebo-controlled, Phase 3, parallel-group study with optional open-label extension.