This is a randomized, double-blind, placebo-controlled Phase II study in which approximately 36 patients will be randomized in a 1:1:1 ratio to receive either ARGX-113 Dose A, or ARGX-113 Dose B body weight or placebo in 4 infusions administered 1-week apart in addition to Standard-of-Care (SoC) treatment. Patients aged 18 to 85 years (inclusive) with confirmed primary immune thrombocytopenia (ITP) who have a platelet count ˂ 30 × 109/L and who are receiving oral corticosteroids and/or permitted oral immunosuppressants and/or Thrombopoietin receptor (TPO-R) agonist as SoC which must be maintained on a stable dose and frequency for at least 4 weeks prior to Screening.~The study will include a 2-week Screening, a 3-week Treatment period, and an 21-week follow-up (FU) period. The study is followed by an open label period where patients will be given the option to be treated with ARGX-113 Dose A in cycles of 4 weekly infusions with a minimum of 4 weeks apart. Patients may receive rescue therapy during the study at the discretion the investigator when deemed medically necessary.
The purpose of the study is to determine safety, efficacy, tolerability and Pharmacokinetics of ARGX-113 in Patients with Primary Immune Thrombocytopenia.