An Open-label Study to Investigate the Clinical Efficacy of Different Dosing Regimens of Efgartigimod IV in Patients With Generalized Myasthenia Gravis

Inclusion Criteria:

• Capable of giving signed informed consent, which includes compliance with therequirements and restrictions listed in the informed consent form (ICF) and in thisprotocol.

• At least 18 years of age, at the time of signing the informed consent.

• Diagnosed with Generalized Myasthenia Gravis (gMG) with confirmed documentation andsupported by a physical exam and confirmed seropositivity for anti-acetylcholinereceptor antibodies (AChR-Abs).

• Meets the clinical criteria as defined by the Myasthenia Gravis Foundation ofAmerica (MGFA) class II, III, or IV

• Has an Myasthenia Gravis - Activities of Daily Living (MG-ADL) total score ≥5 atscreening and the day 1 visit, with more than 50% of the score due to nonocularsymptoms

• Concomitant gMG treatment is permitted. Permitted concomitant gMG treatment includesnonsteroidal immunosuppressive drugs (NSIDs), steroids, and/or acetylcholinesterase (AChE) inhibitors. If receiving corticosteroids and/or NSIDs, must be on a stabledose for at least 1 month before screening.

• Contraceptive use should be consistent with local regulations regarding the methodsof contraception for those participating in clinical studies and: Women ofchildbearing potential must have a negative serum pregnancy test at screening and anegative urine pregnancy test at baseline before investigational medicinal product (IMP) can be administered.

Exclusion Criteria:

• Clinically significant uncontrolled active or chronic bacterial, viral, or fungalinfection at screening

• A positive test for SARS-CoV-2 at screening

• Any other known autoimmune disease that, in the opinion of the investigator, wouldinterfere with an accurate assessment of the clinical symptoms of gMG and/or put theparticipant at undue risk

• History of malignancy unless deemed cured by adequate treatment with no evidence ofreoccurrence for ≥3 years before the first administration of the IMP. Participantswith the following cancers can be included at any time, provided they are adequatelytreated at screening: Basal cell or squamous cell skin cancer; carcinoma in situ ofthe cervix; Carcinoma in situ of the breast; Incidental histological finding ofprostate cancer (TNM stage T1a or T1b)

• Clinical evidence of other significant serious diseases, a recent (<3 months) majorsurgery, or any other condition that, in the opinion of the investigator, couldconfound the results of the study or put the participant at undue risk

• A thymectomy within 3 months of screening

• Pregnant or lactating females and those who intend to become pregnant during thestudy or within 90 days of the last dose of IMP

• Use of the following prior or concomitant therapies:

1. intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg) within 14 days of day 1

2. Rituximab within 6 months of day 1

3. Eculizumab within 1 month of day 1

4. Other monoclonal antibodies (eg, adalimumab, tocilizumab, ixekizumab) within 5half-lives of the monoclonal antibodies before day 1

5. Use of any other investigational product within 3 months or 5 half-lives,whichever is longer, before day 1

6. Receipt of a live or live-attenuated vaccines received within 4 weeks ofscreening. The receipt of any inactivated, subunit, polysaccharide, conjugatevaccine at any time before screening is not considered exclusionary.

• Previous participation in a clinical study or patient access program during whichthey were treated with efgartigimod

• Positive serum test at screening for an active viral infection with any of thefollowing conditions: Hepatitis B virus (HBV) that is indictive of an acute orchronic infection; Hepatitis C virus (HCV) based on HCV antibody assay (unlessassociated with a negative HCV RNA test); HIV based on test results that areassociated with an AIDS-defining condition or a CD4 count <200 cells/mm3

• Total IgG <6 g/L at screening

• Known hypersensitivity reaction to efgartigimod or any of its excipients

• The participant stands in any relationship of dependency with the sponsor.

• The participant has been institutionalized due to an official or judicial order.