A Study to Evaluate the Efficacy and Safety of Efgartigimod PH20 Subcutaneous in Adult Patients With Primary Immune Thrombocytopenia

Inclusion criteria

• Ability to understand the requirements of the trial and provide written informed consent, willing and able to comply with the trial protocol procedures
• Is at least the local age of consent for clinical studies when signing the ICF.
• Confirmed diagnosis of primary ITP made at least 3 months before randomization and based on the American Society of Hematology Criteria, and no known etiology for thrombocytopenia
• Diagnosis supported by a response to a prior ITP therapy (other than TPO-RAs), in the opinion of the investigator
• Mean platelet count of 1.5 or activated partial thromboplastin time >1.5×upper limit of normal - OR - total IgG level <6 g/L
• History of malignancy unless deemed cured by adequate treatment with no evidence of recurrence for ≥3 years before the first administration of IMP. Participants with the following cancer can be included at any time: Adequately treated 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 (TNM stage T1a or T1b)
• Uncontrolled hypertension, defined as a repeated elevated blood pressure exceeding 160 mmHg (systolic) and/or 100 mmHg (diastolic) despite appropriate treatments
• History of any major thrombotic or embolic event (eg, myocardial infarction, stroke, deep venous thrombosis, or pulmonary embolism) within 5 years prior to randomization
• History of coagulopathy or hereditary thrombocytopenia or a family history of thrombocytopenia
• Evidence of an active clinically significant bleeding of an organ or internal mucosal bleeding, other than expected in ITP, that warrants emergent treatment or therapeutic procedure based on the investigator's judgment (eg, intracranial hemorrhage, pulmonary hemorrhage, bleeding with ongoing need for packed red blood cell transfusion)
• Estimated high risk of a clinically significant bleeding of an organ or internal mucosal bleeding, other than expected in ITP, that warrants emergent treatment or therapeutic procedure according to the investigator's judgment
• Clinical evidence of other significant serious diseases, have had a recent major surgery, or who have any other condition in the opinion of the investigator, that could confound the results of the trial or put the participant at undue risk
• Positive serum test at screening for an active viral infection with any of the following conditions: Hepatitis B virus (HBV) that is indicative of an acute or chronic infection, unless associated with a negative HBV DNA test, Hepatitis C virus (HCV) based on HCV-antibody assay (unless associated with a negative HCV RNA test), Human immunodeficiency virus (HIV) based on test results that are associated with an acquired immunodeficiency syndrome (AIDS)-defining condition or a CD4 count ≤200 cells/mm3
• Known hypersensitivity reaction to efgartigimod, rHuPH20, or 1 of its excipients
• Previously participated in a clinical trial with efgartigimod and have received at least 1 administration of the IMP
• Pregnant or lactating or intends to become pregnant during the trial
• Clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection at screening
• Any other known autoimmune disease that, in the opinion of the investigator, would interfere with an accurate assessment of clinical symptoms of ITP or put the participant at undue risk
• Clinical evidence of significant unstable or uncontrolled acute or chronic diseases other than ITP (eg, cardiovascular, pulmonary, hematologic, gastrointestinal, endocrine, hepatic, renal, neurological, malignancy, infectious diseases, uncontrolled diabetes) despite appropriate treatments which could put the participant at undue risk
• Current or history of (ie, within 12 months of screening) alcohol, drug, or medication abuse
• Received a live/live-attenuated vaccine less than 4 weeks before screening. The receipt of any inactivated, sub-unit, polysaccharide, or conjugate