A Phase 3 Study to Evaluate Claseprubart in Adults With Generalized Myasthenia Gravis (EMERGE)

The study includes the following periods:

• Screening (up to 12 weeks)
• Randomized, blinded, controlled treatment (RCT) period (17 weeks)
• Extended treatment period (ETP) (104 weeks) (optional) for eligible participants [includes blinded extension period (BEP) and open-label extension (OLE) period]
• Safety Follow-Up period (40 weeks)

Inclusion criteria

• Must have given written informed consent before any study-related activities are carried out
• Weight range between 40-130 kg at Screening
• Diagnosis of gMG by the following tests:

• Acetylcholine receptor antibody (AChR Ab) positive, and
• 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 be of non-childbearing potential, or 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
• Male participants 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

Exclusion criteria

• 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
• Known complement deficiency
• Prior history (at any time) of N. meningitidis infection
• 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
• Previous treatment with claseprubart (DNTH103) or participation in a clinical trial with claseprubart. [
• Any thymic surgery/biopsy within 1 year of Screening
• Any known or untreated thymoma.
• Any history of thymic carcinoma or thymic malignancy
• 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
• Concurrent or previous use of the following medication within the time periods specified below.

• Rituximab or other B-cell targeting therapies (ie, inebilizumab) within 6 months (180 days) prior to randomization (Day 1);
• Intravenous immunoglobulin (IVIg) and plasma exchange (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
• Diagnosis of systemic lupus erythematosus (SLE) or family history (defined as a parent, sibling, or child) of SLE