A Study of Efgartigimod IV in Participants From 12 Years to Less Than 18 Years of Age With Chronic Immune Thrombocytopenia (ITP)

A Multicenter, Randomized, Double-blinded, Parallel-Arm, Placebo-Controlled, Pharmacokinetic and Pharmacodynamic Study Followed by an Open-Label Arm to Evaluate Efgartigimod IV in Pediatric Participants From 12 Years to Less Than 18 Years of Age With Chronic ITP

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

Study Overview

• Status: Recruiting
• Conditions: Idiopathic Thrombocytopenic Purpura; Immune Thrombocytopenic Purpura; ITP; Immune Thrombocytopenia (ITP); Idiopathic Thrombocytopenic Purpura (ITP); Immune Thrombocytopenic Purpura ( ITP ); ITP - Immune Thrombocytopenia
• Intervention / Treatment: Biological: Efgartigimod IV; Other: Placebo IV

• Study Type: Interventional
• Enrollment (Estimated): 24
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Sabine Coppieters, MD; Phone Number: 857-350-4834; Email: clinicaltrials@argenx.com

Study Locations

• Germany
  • Berlin, Germany, 13353
    • Recruiting
    • Charite - Universitaetsmedizin Berlin - Campus Virchow-Klinikum (CVK)
    • Contact: Susanne Holzhauer, MD; Phone Number: +1 857-350-4834; Email: clinicaltrials@argenx.com
• Italy
  • Genoa, Italy, 16147
    • Recruiting
    • Gaslini Children's Hospital
    • Contact: Maurizio Miano, MD; Phone Number: +3901056363683; Email: mauriziomiano@gaslini.org
  • Roma, Italy, 165
    • Active, not recruiting
    • Bambino Gesu Children's Hospital
• Poland
  • Lublin, Poland, 20-093
    • Recruiting
    • Uniwersytecki Szpital Dzieciecy w Lublinie
    • Contact: Katarzyna Drabko, MD; Phone Number: +48606729876; Email: katarzyna.drabko@umlub.pl
• Romania
  • Bucharest, Romania, 022328
    • Recruiting
    • Institutul Clinic Fundeni
    • Contact: Anca Colita, MD; Phone Number: +40213172194; Email: secretariat@icfundeni.ro
• Spain
  • Barcelona, Spain, 08035
    • Recruiting
    • Hospital Universitari Vall d'Hebron
    • Contact: Thais Murciano Carrillo, MD; Phone Number: 0034934893093; Email: thais.murciano@vallhebron.cat
  • Esplugues de Llobregat, Spain, 08950
    • Recruiting
    • Hospital Sant Joan de Deu Barcelona
    • Contact: Ruben Berrueco Moreno, MD; Phone Number: 0034936009733; Email: ruben.berrueco@sjd.es
  • Madrid, Spain, 28009
    • Recruiting
    • Hospital Infantil Universitario Nino Jesus (HIUNJS)
    • Contact: Julian Sevilla Navarro, MD; Phone Number: 0034915036900; Email: julian.sevilla@salud.madrid.org
  • Madrid, Spain, 28009
    • Recruiting
    • Hospital Materno-Infantil Universitario Gregorio Maranon
    • Contact: David Diaz Perez, MD; Phone Number: 0037915290037; Email: ddiazp@salud.madrid.org
• United Kingdom
  • Cardiff, United Kingdom, CF14 4XW
    • Recruiting
    • Cardiff and Vale NHS Trust - University Hospital of Wales (UHW)
    • Contact: Philip Connor, MD; Phone Number: 857-350-4834; Email: clinicaltrials@argenx.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 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
• Has documented insufficient response to a prior ITP treatment with corticosteroids, IVIg, anti-D immunoglobulin, TPO-RAs, rituximab, or splenectomy
• Has documented mean platelet count of less than 30 x10^9/L

Exclusion Criteria:

• 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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Efgartigimod IV; Participants receiving efgartigimod IV during the double-blinded treatment period and the open-label treatment period(s)	Biological: Efgartigimod IV; Intravenous infusion of efgartigimod
Placebo Comparator: Placebo IV; Participants receiving placebo IV during the double-blinded treatment period and receiving efgartigimod IV during the open-label treatment period(s)	Biological: Efgartigimod IV; Intravenous infusion of efgartigimod; Other: Placebo IV; Intravenous infusion of placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Efgartigimod serum concentrations in the DBTP	Up to 24 weeks
Total IgG levels in the DBTP	Up to 24 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Efgartigimod serum concentrations over time during the DBTP		Up to 24 weeks
Percent change from baseline in total IgG levels in serum over time during the DBTP		Up to 24 weeks
Incidence of AEs, SAEs and AEs leading to IMP discontinuation	SAE: Serious adverse event; AE: adverse event	Up to 136 weeks
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	Up to 48 weeks
Extent of disease control during the DBTP and during the first 24 weeks of OLTP1 for those participants receiving placebo in the DBTP	Extend of disease defined as the number of cumulative weeks with a platelet count of ≥50 × 10^9/L	Up to 48 weeks
Changes from baseline for platelet counts over time		Up to 76 weeks
Incidence of bleeding, assessed by the Modified Buchanan and Adix Bleeding Score for pediatric ITP	The Modified Buchanan and Adix Bleeding Score for pediatric ITP is a semiquantitative assessment tool that measures bleeding signs and symptoms, comprising a score based on a scale of 0 to 5, each representing a different level of severity (0 = no risk; 5 = highest severity).	Up to 76 weeks
Incidence of ADA and Nab against efgartigimod in serum	ADA: anti-drug antibodies; Nab: neutralizing antibodies	Up to 76 weeks
Change from baseline in EQ-5D-5L	The European Quality of Life 5 Dimensions 5 Level (EQ-5D-5L) is a questionnaire comprised of 5 dimensions. Participants are asked to select the statement in each dimension which best describes their health on the day they complete the questionnaire. Responses in each dimension are coded as a 1-digit number ranging from 1 (no problems) to 5 (extreme problems).	Up to 76 weeks
Change from baseline in KIT Child Self-Report and KIT Parent Impact Report	The Kids' ITP Tools (KIT) comprises two disease- specific tools: a self-report form for children aged 12 and older, and a parent impact form. Respondents provide insights into their disease experience using a 1-week recall period. The instrument generates a total score, calculated by summing the items and converting them to a scale of 0 to 100, where higher scores reflect a better disease-specific quality of life (QoL).	Up to 76 weeks
Change from baseline in peds FACIT-F	In all participants, the pediatric Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) will use to assess health-related quality of life (HRQoL) before and after treatment. The FACIT-F questionnaire has a score range of 0 to 52, where 0 represents the worst possible fatigue and 52 indicates no fatigue.	Up to 76 weeks

Collaborators and Investigators

• Sponsor: argenx

Publications and helpful links

Helpful Links

• Study website

Study record dates

Study Major Dates

• Study Start (Actual): October 20, 2025
• Primary Completion (Estimated): October 1, 2028
• Study Completion (Estimated): October 1, 2030

Study Registration Dates

• First Submitted: September 19, 2025
• First Submitted That Met QC Criteria: September 19, 2025
• First Posted (Actual): September 26, 2025

Study Record Updates

• Last Update Posted (Actual): June 12, 2026
• Last Update Submitted That Met QC Criteria: June 11, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cytopenia; Pathologic Processes; Autoimmune Diseases; Immune System Diseases; Hemorrhage; Skin Manifestations; Hematologic Diseases; Blood Coagulation Disorders; Hemorrhagic Disorders; Blood Platelet Disorders; Thrombotic Microangiopathies; Purpura, Thrombocytopenic; Purpura; Thrombocytopenia; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Hemic and Lymphatic Diseases; Purpura, Thrombocytopenic, Idiopathic
• Other Study ID Numbers: ARGX-113-2409; 2025-521055-23-00 (Ctis)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No