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

The purpose of this open-label study is to investigate the efficacy, safety, and tolerability of a continuous regimen of efgartigimod compared with a cyclic regimen in participants with Generalized Myasthenia Gravis (gMG).

Study details include:

The study duration will be up to 138 weeks (including screening and a safety follow-up of up to 9 weeks)

* Part A (regimen comparison period) - 21 weeks
* Part B (extension period) - up to 105 weeks

The visit frequency, including virtual visits, will be weekly through Week 21 and every 5 weeks for the remainder of the study.


Eligibility Criteria:
Inclusion Criteria:

* Capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.
* At least 18 years of age, at the time of signing the informed consent.
* Diagnosed with Generalized Myasthenia Gravis (gMG) with confirmed documentation and supported by a physical exam and confirmed seropositivity for anti-acetylcholine receptor antibodies (AChR-Abs).
* Meets the clinical criteria as defined by the Myasthenia Gravis Foundation of America (MGFA) class II, III, or IV
* Has an Myasthenia Gravis - Activities of Daily Living (MG-ADL) total score ≥5 at screening and the day 1 visit, with more than 50% of the score due to nonocular symptoms
* Concomitant gMG treatment is permitted. Permitted concomitant gMG treatment includes nonsteroidal immunosuppressive drugs (NSIDs), steroids, and/or acetylcholinesterase (AChE) inhibitors. If receiving corticosteroids and/or NSIDs, must be on a stable dose for at least 1 month before screening.
* Contraceptive use should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies and: Women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at baseline before investigational medicinal product (IMP) can be administered.

Exclusion Criteria:

* Clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection at screening
* A positive test for SARS-CoV-2 at screening
* Any other known autoimmune disease that, in the opinion of the investigator, would interfere with an accurate assessment of the clinical symptoms of gMG and/or put the participant at undue risk
* History of malignancy unless deemed cured by adequate treatment with no evidence of reoccurrence for ≥3 years before the first administration of the IMP. Participants with the following cancers can be included at any time, provided they are adequately treated at screening: Basal cell or squamous cell skin cancer; carcinoma in situ of the cervix; Carcinoma in situ of the breast; Incidental histological finding of prostate cancer (TNM stage T1a or T1b)
* Clinical evidence of other significant serious diseases, a recent (\<3 months) major surgery, or any other condition that, in the opinion of the investigator, could confound 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 the study 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 5 half-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 of screening. The receipt of any inactivated, subunit, polysaccharide, conjugate vaccine at any time before screening is not considered exclusionary.
* Previous participation in a clinical study or patient access program during which they were treated with efgartigimod
* Positive serum test at screening for an active viral infection with any of the following conditions: Hepatitis B virus (HBV) that is indictive of an acute or chronic infection; Hepatitis C virus (HCV) based on HCV antibody assay (unless associated with a negative HCV RNA test); HIV based on test results that are associated 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.