Study of ALXN2050 in Adult Participants With Generalized Myasthenia Gravis

Prior treatment

• History of thymectomy, thymomectomy, or any other thymic surgery within 12 months prior to the Screening Visit.
• Clinical features consistent with Clinical Deterioration at the time of the Screening Visit or at any time during the Screening Period prior to randomization (Day 1).
• Use of the following within the time periods specified below:
  • Intravenous immunoglobulin G or subcutaneous immunoglobulin within the 4 weeks (28 days) prior to the Screening Visit.
  • Use of tacrolimus or cyclosporine within the 4 weeks (28 days) prior to the Screening Visit.

Other illness

• Estimated glomerular filtration rate ≤ 30 milliliters/minute/1.73 squared meters during Screening calculated by Chronic Kidney Disease Epidemiology Collaboration.
• Any untreated thymic malignancy, carcinoma, or thymoma. Participants with a history of treated thymic malignancy or carcinoma are eligible for enrollment if they meet pre-specified conditions outlined in the protocol.

• Diagnosed with MG at least 3 months (90 days) prior to the date of the Screening Visit. Confirmation of MG must be made via the following:
  • Positive serologic test for anti AChR antibodies at the Screening Visit, and
  • Abnormal neuromuscular transmission demonstrated by single fiber electromyography or repetitive nerve stimulation, or
  • Positive response to an AChEI test (eg, edrophonium chloride test), or
  • Improvement of signs or symptoms related to MG during treatment with an oral AChEI, as determined by the treating physician
• Myasthenia Gravis Foundation of America Clinical Classification Class II to IV at the Screening Visit.
• MG-ADL total score must be ≥ 5 (with at least 50% of the score attributed to non-ocular elements) at the Screening Visit and at randomization (Day 1).
• Participants receiving treatment with protocol-specified immunosuppressive therapies, corticosteroids, or acetylcholinesterase inhibitors must have been receiving treatment and on a stable dose prior to the date of the Screening Visit, with no changes to the regimen expected during screening, the PEP, and/or the ETP.