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Ability to understand the requirements of the trial and provide written informed consent, willing and able to comply with the trial protocol procedures |
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Male or female, aged ≥18 years at the time the informed consent form (ICF) is signed. Exceptions are made for The Republic of South Korea and Taiwan where, according to local regulatory requirements, legal age is reached at 19 years and 20 years, respectively |
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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 |
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Diagnosis supported by a response to a prior ITP therapy (other than TPO-RAs), in the opinion of the investigator |
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Mean platelet count of <30×10E9/L from at least 3 documented, qualifying counts within the 3 preceding months where at least 2 of the qualifying counts must be taken during the screening period: 1 platelet count collected during the screening period and the predose platelet count on the day of randomization (visit 1). If the third count is not available from the 3 preceding months, this third platelet count can be obtained during the screening period |
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A documented history of a platelet count of <30×10E9/L before screening |
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Permitted concurrent ITP medications include corticosteroids, danazol, vinca alkaloids |
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oral immunosuppressants, dapsone, fostamatinib, and/or oral TPO-RAs |
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At the start of the trial, the participant either takes concurrent ITP treatment(s) and has received at least 1 prior therapy for ITP in the past, or the participant does not take treatment for ITP (see note) but has received at least 2 prior treatments for ITP. Participants receiving permitted concurrent ITP treatment(s) at baseline must have been stable in dose and frequency for at least 4 weeks before randomization |
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Agree to use contraceptive measures consistent with local regulations and the protocol |
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Use of any transfusions within 4 weeks prior to randomization
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Use of romiplostim within 4 weeks prior to randomization
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Secondary ITP/thrombocytopenia associated with another condition, eg, lymphoma
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Undergone splenectomy less than 4 weeks prior to randomization
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chronic lymphocytic leukemia, viral infection, hepatitis, induced or alloimmune
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thrombocytopenia, thrombocytopenia associated with myeloid dysplasia, or hematopoietic
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Hemoglobin ≤9 g/dL - OR - International normalized ratio >1.5 or activated partial
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stem cell transplant
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thromboplastin time >1.5×upper limit of normal - OR - total IgG level <6 g/L
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At the screening visit, clinically significant laboratory abnormalities as follows
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Use of anticoagulants (eg, vitamin K antagonists, direct oral anticoagulants) within 4
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weeks prior to randomization
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following cancer can be included at any time: Adequately treated basal cell or
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Use of Ig (IV, SC, or intramuscular route) or plasmapheresis (PLEX) within 4 weeks
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squamous cell skin cancer, Carcinoma in situ of the cervix, Carcinoma in situ of the
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prior to randomization
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breast or Incidental histological finding of prostate cancer (TNM stage T1a or T1b)
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Use of an investigational product within 3 months or 5 half-lives (whichever is
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longer) before the first dose of the IMP
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Use of any monoclonal antibody or Fc fusion proteins, other than those previously
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indicated, within 6 months before the first dose of the IMP (eg, anti-CD20)
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History of malignancy unless deemed cured by adequate treatment with no evidence of
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Known hypersensitivity reaction to efgartigimod, rHuPH20, or 1 of its excipients
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recurrence for ≥3 years before the first administration of IMP. Participants with the
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following conditions: Hepatitis B virus (HBV) that is indicative of an acute or
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chronic infection, unless associated with a negative HBV DNA test, Hepatitis C virus
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(HCV) based on HCV-antibody assay (unless associated with a negative HCV RNA test)
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Uncontrolled hypertension, defined as a repeated elevated blood pressure exceeding 160
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Human immunodeficiency virus (HIV) based on test results that are associated with an
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mmHg (systolic) and/or 100 mmHg (diastolic) despite appropriate treatments
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acquired immunodeficiency syndrome (AIDS)-defining condition or a CD4 count ≤200
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History of any major thrombotic or embolic event (eg, myocardial infarction, stroke
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cells/mm3
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deep venous thrombosis, or pulmonary embolism) within 12 months prior to randomization
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History of coagulopathy or hereditary thrombocytopenia or a family history of
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thrombocytopenia
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Evidence of an active clinically significant bleeding of an organ or internal mucosal
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Pregnant or lactating or intends to become pregnant during the trial
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bleeding, other than expected in ITP, that warrants emergent treatment or therapeutic
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procedure based on the investigator's judgment (eg, intracranial hemorrhage, pulmonary
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hemorrhage, bleeding with ongoing need for packed red blood cell transfusion)
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Estimated high risk of a clinically significant bleeding of an organ or internal
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mucosal bleeding, other than expected in ITP, that warrants emergent treatment or
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therapeutic procedure according to the investigator's judgment
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Clinical evidence of other significant serious diseases, have had a recent major
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surgery, or who have any other condition in the opinion of the investigator, that
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could confound the results of the trial or put the participant at undue risk
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Positive serum test at screening for an active viral infection with any of the
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Previously participated in a clinical trial with efgartigimod and have received at
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least 1 administration of the IMP
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Clinically significant uncontrolled active or chronic bacterial, viral, or fungal
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infection at screening
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Any other known autoimmune disease that, in the opinion of the investigator, would
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interfere with an accurate assessment of clinical symptoms of ITP or put the
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participant at undue risk
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Clinical evidence of significant unstable or uncontrolled acute or chronic diseases
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other than ITP (eg, cardiovascular, pulmonary, hematologic, gastrointestinal
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endocrine, hepatic, renal, neurological, malignancy, infectious diseases, uncontrolled
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diabetes) despite appropriate treatments which could put the participant at undue risk
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Current or history of (ie, within 12 months of screening) alcohol, drug, or medication
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abuse
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Received a live/live-attenuated vaccine less than 4 weeks before screening. The
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receipt of any inactivated, sub-unit, polysaccharide, or conjugate vaccine at any time
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before screening is not considered an exclusion criterion
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