Evaluating Efgartigimod in Patients with Guillain-Barré Syndrome

Inclusion Criteria:

• Provision of signed and dated informed consent form

• Stated willingness to comply with all study procedures and availability for theduration of the study

• Male or female, aged 18 years or older

• Have a diagnosis of GBS according to the National Institute of NeurologicalDisorders and Stroke Diagnostic Criteria for Guillain-Barré Syndrome

• Onset of GBS-related weakness ≤14 days prior to infusion

• GBS-DS score of 3, 4, or 5

Exclusion Criteria:

• Pregnant and lactating women, and those intending to become pregnant during thetrial or within 90 days after the last dosing. Women of childbearing potentialshould have a negative serum pregnancy test at Screening and a negative urinepregnancy test at Baseline prior to administration of IMP. Note: Women ofchildbearing potential should use a highly effective method of contraception (i.e.,pregnancy rate of less than 1% per year) during the trial and for 90 days after thelast administration of the IMP. They must be on a stable regimen, for at least 1month, of combined estrogen and progestogen hormonal contraception with inhibitionof ovulation, progestogen-only hormonal contraception associated with inhibition ofovulation, intrauterine device (IUD), intrauterine hormone-releasing system,bilateral tubal occlusion, vasectomized partner, or agree upon continuous abstinencefrom heterosexual sexual contact.

• Male patients who are sexually active and do not intend to use effective methods ofcontraception (as mentioned above) during the trial or within 90 days after the lastdosing or male patients who plan to donate sperm during the trial or within 90 daysafter the last dosing. Note: Sterilized male patients who have had vasectomy withdocumented aspermia post-procedure, or male patients who have a partner ofnon-childbearing potential, can be included.

• GBS DS of 2 or less.

• Patients with any known severe bacterial, viral or fungal infection or any majorepisode of infection that required hospitalization or injectable antimicrobialtherapy in the last 8 weeks prior to Screening.

• Patients with more than 14 days after onset of symptoms.

• Patients with known IgG deficiency.

• Patients with recurrent GBS.

• Use of investigational drug within 3 months or 5 half-lives of the drug (whicheveris longer) prior to Screening.

• Patients who have a history of malignancy, including malignant thymoma, ormyeloproliferative or lymphoproliferative disorders, unless deemed cured by adequatetreatment with no evidence of recurrence for ≥ 3 years before Screening. Patientswith completely excised non-melanoma skin cancer (such as basal cell carcinoma orsquamous cell carcinoma) or cervical carcinoma in situ would be permitted at anytime.

• Patients with clinical evidence of other significant serious disease or patients whounderwent a recent major surgery, which could confound the results of the trial orput the patient at undue risk. Patients with renal/hepatic function impairment canbe included.