EMERGE

Prior treatment

• Concurrent or previous use of the following medications within the time periods specified below. a. Rituximab or other B-cell targeting therapies (ie, inebilizumab) within 6 months (180 days) prior to randomization (Day 1); b. IVIg and PLEX within 4 weeks (28 days) prior to randomization (Day 1).
• Participation in another clinical study of an investigational drug within 90 days or 5 half-lives of the investigational agent
• Prior history (at any time) of N. meningitidis infection.
• Previous treatment with claseprubart (DNTH103) or participation in a clinical trial with claseprubart
• Any thymic surgery/biopsy within 1 year of Screening.
• History of active malignancy within 5 years prior to Screening, except basal cell carcinoma of the skin, curatively resected squamous cell carcinoma of the skin, cervical carcinoma in situ curatively treated or low-grade prostate adenocarcinoma for which appropriate management is observation alone.

Other illness

• History or presence of significant medical/surgical condition including any acute illness, mental illness, or major surgery considered to be clinically significant or that could have potential impact on safety/efficacy or study procedures
• Participants with known seropositivity or who test positive for an active viral infection with human immunodeficiency virus (HIV-1 or HIV-2), hepatitis B (HBV; except participants who are seropositive because of HBV vaccination) or hepatitis C virus (HCV) during Screening
• Any history of thymic carcinoma or thymic malignancy

Other

• Diagnosis of systemic lupus erythematosus (SLE) or family history (defined as a parent, sibling, or child) of SLE.
• Known complement deficiency.
• Any known or untreated thymoma.

• Must have given written informed consent before any study-related activities are carried out
• Male participants must: a. Agree not to donate sperm and, if engaging in sexual intercourse with a female partner who could become pregnant, must agree to use an acceptable method of contraception or b. Be permanently surgically sterile for at least 90 days prior to Screening.
• Adult males and females, between the ages of 18 to 80 years of age at Screening
• Weight range between 40 kg and 130 kg at Screening
• Diagnosis of gMG by the following tests: a. Acetylcholine receptor antibody (AChR-Ab) positive, and b. One of the following: i. History of abnormal neuromuscular transmission test; ii. History of positive anticholinesterase test; iii. Clinical response to acetylcholinesterase inhibitors.
• Myasthenia Gravis Foundation of America (MGFA) Class II-IVa
• MG-ADL scale score of 6 or more
• QMG scale score of 10 or more
• Documented vaccinations against encapsulated bacteria in accordance with local requirements and based on vaccine availability.
• Female participants must: a. Be of nonchildbearing potential, or b. If of childbearing potential, must agree not to donate ova, not to attempt to become pregnant and, if engaging in sexual intercourse with a male partner, must agree to use a highly effective method of contraception