Study for Patients with Primary Immune Thrombocytopenia

This study is testing an experimental drug called efgartigimod and the purpose of this study is to test efgartigimod at different dose levels to find out if it is safe and effective in people with primary immune thrombocytopenia (ITP).

In order to participate you must meet the following criteria:

• Have the ability to understand the requirements of the trial and provide written informed consent (including consent for the use and disclosure of research-related health information), willing and able to comply with the trial protocol procedures (including attending the required trial visits).
• Are male or female, at least 18 years of age at the time the informed consent form (ICF) is signed.
• Have 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.
• Have a diagnosis supported by a response to a prior ITP therapy (other than TPO-RAs), in the opinion of the investigator.
• Have mean platelet count of <30×109/L from 2 counts: 1 platelet count collected during the screening period and the predose platelet count on the day of randomization (visit 1).
• Have a documented history of a platelet count of <30×109/L before screening.
• 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.
  • Permitted concurrent ITP medications include corticosteroids, danazol, vinca alkaloids, oral immunosuppressants, dapsone, fostamatinib, and/or oral TPO-RAs.
  • Note: Participants not receiving concurrent ITP therapy are also eligible for the trial if they have not received prior ITP therapy for at least 4 weeks before baseline, and 6 months in case of prior ITP therapy with an anti-CD20 therapy (eg, rituximab).argenx BV ARGX-
• Women of childbearing potential:
  • As defined in Woman of Childbearing Potential, women of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test at baseline before trial medication can be administered
  • Must be on a stable regimen for at least 1 month of at least 1 highly effective method of contraception (ie, failure rate of less than 1% per year; see Highly Effective Methods of Female Contraception) during the trial and for 90 days after the last administration of IMP
• Non-sterilized male participants who are sexually active with a female partner of childbearing potential must use effective contraception (see Male Contraception) from signing the ICF through 90 days after the last administration of the IMP. Male participants practicing true sexual abstinence (as consistent with preferred and usual lifestyle) can be included. Sterilized male participants who have had a vasectomy and with documented absence of sperm post-procedure can be included. Male participants are not allowed to donate sperm from signing the ICF through 90 days after the last dose of the IMP.

You will be excluded from the study if any of the following criteria apply to you:

• Have secondary ITP/thrombocytopenia associated with another condition, eg, lymphoma, chronic lymphocytic leukemia, viral infection, hepatitis, induced or alloimmune thrombocytopenia, thrombocytopenia associated with myeloid dysplasia, or hematopoietic stem cell transplant.
• Have used anticoagulants (eg, vitamin K antagonists, direct oral anticoagulants) within 4 weeks prior to randomization.
• Use of any transfusions within 4 weeks prior to randomization.
• Use of Ig (IV, SC, or intramuscular route) or plasmapheresis (PLEX) within 4 weeks prior to randomization.
• Use of romiplostim within 4 weeks prior to randomization.
• Have undergone splenectomy less than 4 weeks prior to randomization.
• Use of an investigational product within 3 months or 5 half-lives (whichever is longer) before the first dose of the IMP.
• Use of any monoclonal antibody within 6 months before the first dose of the IMP (eg, anti-CD20).
• At the screening visit, clinically significant laboratory abnormalities as follows:
  • Hemoglobin ≤9 g/dL
    - OR –
  • International normalized ratio >1.5 or activated partial thromboplastin time >1.5×upper limit of normal
    - OR –
  • Total IgG level <6 g/L
• Have a 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)
• Have uncontrolled hypertension, defined as a repeated elevated blood pressure exceeding 160 mmHg (systolic) and/or 100 mmHg (diastolic) despite appropriate treatments.
• Have a history of any major thrombotic or embolic event (eg, myocardial infarction, stroke, deep venous thrombosis, or pulmonary embolism) within 12 months prior to randomization.
• Have a history of coagulopathy or hereditary thrombocytopenia or a family history of thrombocytopenia.
• Have 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.
• Have a 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 (https://www.cdc.gov/hepatitis/HBV/PDFs/SerologicChartv8.pdf)
  • Hepatitis C virus (HCV) based on HCV-antibody assay
  • 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
• Have known hypersensitivity reaction to efgartigimod, rHuPH20, or 1 of its excipients.
• Have previously participated in a clinical trial with efgartigimod and have received at least 1 administration of the IMP.
• Pregnant or lactating females and those who intend to become pregnant during the trial or within 90 days after last dose of the IMP.
• Have clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection at screening.
• Have 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.
• Have 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.
• Have current or a history of (ie, within 12 months of screening) alcohol, drug, or medication abuse.
• Have received a live-attenuated vaccine less than 4 weeks before screening. The receipt of any inactivated, sub-unit, polysaccharide, or conjugate vaccine at any time before screening is not considered an exclusion criterion.

This is a partial list of eligibility requirements. To inquire about your eligibility, please call the contact number provided. If you wish to inquire via email, please include the title of the study in your message.