The main purpose of this study is to confirm the correct dose of efgartigimod IV for treating patients aged 12 to younger than 18 years with chronic immune thrombocytopenia (ITP).
The study consists of a double-blinded treatment period (DBTP) in which the participants will be randomized in a 2:1 ratio to receive either efgartigimod IV or placebo IV. At the end of the treatment period (up to 24 weeks), all participants will receive efgartigimod IV during the first year open-label treatment period (OLTP1). At the end of the first OLTP1, participants may begin a second year (OLTP2). After the OLTP2, the participants will enter a follow-up period (approximately 8 weeks) while off study drug. The participants will be in the study for up to 138 weeks.
More information can be found here: https://clinicaltrials.argenx.com/advancejunior
Is aged 12 to less than 18 years when completing the informed consent process
Has a documented duration of primary ITP of more than 12 months on the date the informed consent process is complete
Has documented prior ITP treatment with at least 1 of the following treatments: corticosteroids, IVIg, anti-D immunoglobulin, thrombopoietin receptor agonist (TPO-RAs), or rituximab.
Has documented prior response, defined as 1 platelet count of ≥50 × 10^9/L to at least 1 of the following ITP treatments: prednisone, other or nonspecified corticosteroids, IVIg, or anti-D immunoglobulin
Secondary ITP according to the following definition by the International Working Group (IWG): all forms of immune-mediated thrombocytopenia except primary ITP
Nonimmune thrombocytopenia
ITP-associated critical or severe bleeding
History of hereditary thrombocytopenia
Parallel
Efgartigimod IV
Biological/VaccineIntravenous infusion of efgartigimod
Placebo IV
Other interventionIntravenous infusion of placebo
Efgartigimod serum concentrations in the DBTP
Total IgG levels in the DBTP
Efgartigimod serum concentrations over time during the DBTP
Percent change from baseline in total IgG levels in serum over time during the DBTP
Incidence of AEs, SAEs and AEs leading to IMP discontinuation
SAE: Serious adverse event; AE: adverse event
Sustained platelet count response between study weeks 19 and 24 of the DBTP and in OLTP1 for participants receiving placebo in the DBTP
Sustained platelet count defined as achieving platelet counts of ≥50 × 10\^9/L for at least 4 of the 6 study visits