A Long-term Study to Assess the Safety and Efficacy of Efgartigimod in Adult Patients With Primary Immune Thrombocytopenia (ITP).

Study Overview
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Brief Summary
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This is an open-label long-term multicenter phase 3 trial to evaluate the efficacy and safety of ARGX-113 in adult patients with primary ITP.

Official Title
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A Phase 3, Multicenter, Open-label, Long-term Trial to Evaluate the Safety and Efficacy of Efgartigimod (ARGX 113) 10 mg/kg Intravenous in Adult Patients With Primary Immune Thrombocytopenia.

Conditions
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Primary Immune Thrombocytopenia

Intervention / Treatment
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* Biological: efgartigimod


Participation Criteria
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Eligibility Criteria
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Inclusion criteria: Ability to understand the requirements of the trial, to provide written informed consent (including consent for the use and disclosure of research-related health information), and to comply with the trial protocol procedures (including required trial visits). Patients enrolled in the ARGX-113-1801 trial who completed the 24-weeks trial period. Women of childbearing potential must have a negative urine pregnancy test at baseline before trial medication (infusion) can be administered. Women of childbearing potential should use a highly effective or acceptable method of contraception during the trial and for 90 days after the last administration of the IMP. They must be on a stable regimen, for at least 1 month (as listed in the protocol) 6. Ability to understand the requirements of the additional 52-week treatment period of the trial, to provide written informed consent (including consent for the use and disclosure of research-related health information), and to comply with the trial protocol procedures (including required trial visits). 7. Patient has completed a 52-week treatment period. Exclusion criteria: Introduction or continuation of non-permitted medications during the ARGX-113-1801 trial (such as anti-CD20 therapy, romiplostim, monoclonal antibodies, Fc fusion proteins or live/live-attenuated vaccines). Pregnant or lactating women, and those intending to become pregnant during the trial or within 90 days after the last dosing. Patients with known medical history of hypersensitivity to any of the ingredients of efgartigimod. Use of any other investigational drug or participation in any other investigational trial.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: efgartigimod<br>patients receiving efgartigimod | Biological: efgartigimod<br>* Intravenous infusion of efgartigimod<br>* Other names: ARGX-113;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Frequency and severity of Adverse Events |  | Up to 60 weeks | 
| Frequency and severity of vital signs |  | Up to 60 weeks | 
| Frequency and severity of laboratory assessments |  | Up to 60 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Extent of disease control defined as the percentage of weeks in the trial with platelet counts of ≥50×10E9/L. |  | Over the 52 weeks of treatment | 
| Percentage of patients with overall platelet count response defined as achieving a platelet count of ≥50×10^9/L on at least 4 occasions at any time during the 52-week treatment period. |  | Over the 52 weeks of treatment | 
| Mean change from baseline in platelet count at each visit. |  | Up to 60 weeks, at each visit | 
| For patients rolling-over from the ARGX-113-1801 trial with a platelet count of <30×10^9/L: time to response is defined as the time to achieve 2 consecutive platelet counts of ≥50×10^9/L |  | Up to 60 weeks, at each visit | 
| The percentage of weeks in the trial with platelet counts of ≥30×109/L and at least 20×10E9/L above baseline. |  | Over the 52 weeks of treatment | 
| In patients with baseline platelet count of <15×10E9/L in the current trial (ARGX-113-1803), the percentage of weeks in the trial with platelet counts of ≥30×10E9/L and at least 20×10E9/L above baseline. |  | Over the 52 weeks of treatment | 
| In patients with first exposure to efgartigimod: proportion of patients who achieve a sustained platelet response defined as achieving platelet counts of at least 50×10^9/L for at least 4 of the 6 visits between week 19 and 24 of the trial. |  | Up to 5 weeks, between visit 19 and 24 of the trial | 
| In patients with first exposure to efgartigimod: proportion of patients in the overall population achieving platelet counts of at least 50x10^9/L for at least 6 of the 8 visits between week 17 and 24 of the trial. |  | Up to 7 weeks, between visit 17 and 24 of the trial | 
| Rate of receipt of rescue therapy (rescue per patient per month). |  | Up to 60 weeks, at each visit | 
| Reduction in concurrent ITP therapy. |  | Up to 60 weeks, at each visit | 
| Incidence and severity of the WHO-classified bleeding events. |  | Up to 60 weeks, at each visit | 
| Change from baseline in Patient reported Outcomes (FACIT-Fatigue) at planned visits. |  | Up to 52 weeks | 
| Change from baseline in Patient reported Outcomes (Fact-Th6) at planned visits. |  | Up to 52 weeks | 
| Change from baseline in Quality of Life (SF-36) at planned visits. |  | Up to 52 weeks | 
| Incidence of anti-drug antibodies (ADA) to efgartigimod. |  | Up to 216 weeks | 
| Pharmacokinetic parameter of efgartigimod: serum concentration observed predose (Ctrough). |  | Up to 60 weeks | 
| Pharmacodynamics markers: total IgG. |  | Up to 60 weeks |