Efficacy and tolerability of efgartigimod as early treatment in patients with generalized myasthenia gravis.

Prior treatment

• Have received a live or attenuated vaccine during the month prior to the screening visit.
• Having received any immunosuppressive treatment for MG previously.
• Treatment with IVIG or plasmapheresis within 4 weeks prior to the screening visit.
• Treatment with rituximab or eculizumab within 6 months prior to the screening visit.
• Treatment with any monoclonal antibody at the time of the screening visit.
• History of thymectomy prior to the screening visit or having a thymectomy scheduled during the planned weeks of the study.
• Have any surgical intervention scheduled during the planned weeks of the study.

Other illness

• Active hepatitis B, or positivity for hepatitis C (unless treated and cured) and/or HIV at screening.
• Known autoimmune or non-autoimmune disease that, in the opinion of the treating physician, would interfere with an accurate evaluation of the clinical symptoms of MG or place the patient at undue risk.
• Active or chronic uncontrolled and clinically significant bacterial, viral or fungal infection at the time of the screening visit.

Age

• History of malignancy, unless considered cured with adequate treatment and no evidence of recurrence for ≥ 3 years. (Patients in whom adequate treatment of basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, carcinoma in situ of the breast, or incidental histological finding of prostate cancer -stage can be included at any time). TNM T1a or T1b-).

Other

• MGFA Class I or V.
• Be pregnant and/or breast-feeding or intend to become pregnant during the study or within 90 days of the final dose of efgartigimod.
• Inability to understand informed consent
• Presence of symptoms that may endanger the patient's life if immediate rescue treatment is not instituted (intravenous immunoglobulins -I VIG- or plasma exchange/plasmapheresis), according to the treating physician's criteria.

• Adult patients ≥ 18 years of age, of both sexes.
• Confirmed diagnosis of myasthenia gravis by a neurologist with experience in the disease [clinical symptoms suggestive of MG and positive anti-AChR antibodies and/or an electrophysiological study suggestive of neuromuscular junction disorder]
• Myasthenia Gravis Foundation of America (MGFA) Class II, III, or IV at the time of the screening visit.
• Clinical presentation with 5 or more points (more than 50% of the points for non-ocular symptoms) on the MG-ADL scale.
• Not having received prior immunosuppressive treatment for MG with the exception of corticosteroids that will be started during the study(naïve patients)
• Women of childbearing potential must have a negative serum pregnancy test at screening, be required to use contraception during the study and for 90 days after the last dose of drug, and agree not to donate eggs during the same period.
• Men, agree to use adequate contraception and not donate sperm until the end of the study (and/or until 90 days after the last drug infusion).
• Signed Informed Consent Form.