A Study to Evaluate the Efficacy and Safety of Efgartigimod PH20 Subcutaneous in Adult Patients With Primary Immune Thrombocytopenia (ADVANCE SC)

A Phase 3, Multicenter, Randomized, Double-Blinded, Placebo-Controlled Trial to Evaluate the Efficacy and the Safety of Efgartigimod (ARGX-113) PH20 Subcutaneous in Adult Patients With Primary Immune Thrombocytopenia

This is a phase 3, multicenter, randomized, double-blinded, placebo-controlled, parallel-group trial to evaluate the efficacy, safety, and effect on QoL/PRO of efgartigimod PH20 SC treatment in adult patients with primary ITP.

Study Overview

• Status: Completed
• Conditions: Primary Immune Thrombocytopenia
• Intervention / Treatment: Biological: Efgartigimod PH20 SC; Other: Placebo PH20 SC

• Study Type: Interventional
• Enrollment (Actual): 207
• Phase: Phase 3

Contacts and Locations

Study Locations

• Argentina
  • Buenos Aires, Argentina
    • Investigator Site 0540001
  • Buenos Aires, Argentina
    • Investigator Site 0540004
  • Córdoba, Argentina
    • Investigator Site 0540003
• Australia
  • Adelaide, Australia
    • Investigator Site 0610009
  • Bedford Park, Australia
    • Investigator Site 0610004
  • Box Hill, Australia
    • Investigator Site 0610002
  • Clayton, Australia
    • Investigator Site 0610010
  • Garran, Australia
    • Investigator Site 0610012
  • Hobart, Australia
    • Investigator Site 0610001
  • Perth, Australia
    • Investigator Site 0610011
  • West Perth, Australia
    • Investigator Site 0610003
  • Westmead, Australia
    • Investigator Site 0610005
• Bulgaria
  • Plovdiv, Bulgaria
    • Investigator Site 3590017
  • Sofia, Bulgaria
    • Investigator Site 3590015
• Chile
  • Santiago, Chile
    • Investigator Site 0560002
  • Temuco, Chile
    • Investigator site 0560004
  • Viña Del Mar, Chile
    • Investigator site 0560003
• China
  • Beijing, China
    • Investigator Site 0860003
  • Beijing, China
    • Investigator Site 0860013
  • Bengbu, China
    • Investigator Site 0860008
  • Huizhou, China
    • Investigator Site 0860055
  • Kunming, China
    • Investigator Site 0860009
  • Nanchang, China
    • Investigator Site 0860012
  • Shanxi, China
    • Investigator Site 0860014
  • Shenzhen, China
    • Investigator Site 0860015
  • Tianjin, China
    • Investigator Site 0860001
  • Wenzhou, China
    • Investigator Site 0860006
  • Wuhan, China
    • Investigator Site 0860010
  • Wuxi, China
    • Investigator Site 0860002
  • Zhejiang, China
    • Investigator Site 0860005
  • Zhengzhou, China
    • Investigator Site 0860011
  • Zhenjiang, China
    • Investigator Site 0860058
  • Zhenjiang, China
    • Investigator site 0860062
• Denmark
  • Roskilde, Denmark
    • Investigator Site 0450005
• France
  • Créteil, France
    • Investigator Site 0330009
  • Montpellier, France
    • Investigator Site 0330018
• Georgia
  • Tbilisi, Georgia
    • Investigator Site 9950006
  • Tbilisi, Georgia
    • Investigator site 9950007
  • Tbilisi, Georgia
    • Investigator site 9950008
  • Tbilisi, Georgia
    • Investigator site 9950009
  • Tbilisi, Georgia
    • Investigator site 9950011
  • Tbilisi, Georgia
    • Investigator Site 9950019
• Germany
  • Essen, Germany, 45147
    • Investigator Site 0490008
  • Gießen, Germany
    • Investigator Site 0490012
• Greece
  • Athens, Greece
    • Investigator Site 0300008
  • Athens, Greece
    • Investigator Site 0300010
  • Patra, Greece
    • Investigator Site 0300007
  • Thessaloníki, Greece
    • Investigator Site 0300009
• Ireland
  • Dublin, Ireland
    • Investigator Site 3530002
  • Dublin, Ireland
    • Investigator site 3530003
  • Galway, Ireland
    • Investigator Site 3530001
• Israel
  • Ashkelon, Israel
    • Investigator Site 9720013
  • Haifa, Israel
    • Investigator Site 9720010
  • Haifa, Israel
    • Investigator Site 9720012
  • Jerusalem, Israel
    • Investigator Site 9720008
  • Jerusalem, Israel
    • Investigator Site 9720011
  • Petach Tikva, Israel
    • Investigator Site 9720007
  • Tel Aviv, Israel
    • Investigator Site 9720009
• Italy
  • Alessandria, Italy
    • Investigator Site 0390037
  • Ferrara, Italy
    • Investigator Site 0390043
  • Meldola, Italy
    • Investigator Site 0390045
  • Milan, Italy, 20122
    • Investigator Site 0390014
  • Milan, Italy
    • Investigator Site 0390032
  • Napoli, Italy
    • Investigator Site 0390041
  • Napoli, Italy
    • Investigator Site 0390044
  • Novara, Italy
    • Investigator Site 0390015
  • Potenza, Italy
    • Investigator Site 0390035
  • Reggio Calabria, Italy
    • Investigator Site 0390011
  • Reggio Emilia, Italy, 42100
    • Investigator Site 0390018
  • Rome, Italy
    • Investigator Site 0390046
  • Terni, Italy
    • Investigator Site 0390033
  • Varese, Italy
    • Investigator Site 0390036
• Japan
  • Chiba, Japan
    • Investigator Site 0810056
  • Hirakata, Japan
    • Investigator Site 0810015
  • Hiroshima, Japan
    • Investigator Site 0810010
  • Kanagawa, Japan
    • Investigator Site 0810053
  • Kitakyushu, Japan
    • Investigator Site 0810051
  • Kumamoto, Japan
    • Investigator Site 0810054
  • Maebashi, Japan
    • Investigator Site 0810018
  • Morioka, Japan
    • Investigator Site 0810057
  • Saitama, Japan
    • Investigator Site 0810017
  • Shibukawa, Japan
    • Investigator Site 0810016
  • Shimotsuke, Japan
    • Investigator Site 0810023
  • Shinagawa-Ku, Japan
    • Investigator Site 0810039
  • Tama, Japan
    • Investigator Site 0810038
  • Tokyo, Japan
    • Investigator Site 0810052
  • Tsukuba, Japan
    • Investigator Site 0810048
  • Yamanashi, Japan
    • Investigator Site 0810044
  • Ōgaki, Japan
    • Investigator Site 0810012
• Jordan
  • Amman, Jordan
    • Investigator Site 9620002
  • Irbid, Jordan
    • Investigator site 9620001
• Korea, Republic of
  • Seongnam, Korea, Republic of
    • Investigator Site 0820005
  • Seoul, Korea, Republic of
    • Investigator Site 0820003
  • Seoul, Korea, Republic of
    • Investigator Site 0820004
  • Seoul, Korea, Republic of
    • Investigator Site 0820006
  • Seoul, Korea, Republic of
    • Investigator Site 0820007
  • Seoul, Korea, Republic of
    • Investigator Site 0820008
• Mexico
  • Aguascalientes, Mexico
    • Investigator Site 0520002
  • Chihuahua, Mexico
    • Investigator Site 0520004
  • Mexico, Mexico
    • Investigator Site 0520007
  • Monterrey, Mexico
    • Investigator Site 0520003
  • Oaxaca, Mexico
    • Investigator Site 0520001
• New Zealand
  • Auckland, New Zealand
    • Investigator Site 0640001
  • Christchurch, New Zealand
    • Investigator Site 0640005
  • Palmerston North, New Zealand
    • Investigator Site 0640002
• Norway
  • Bergen, Norway
    • Investigator Site 0470002
  • Oslo, Norway
    • Investigator site 0470003
• Poland
  • Katowice, Poland, 40519
    • Investigator Site 0480013
  • Lublin, Poland
    • Investigator Site 0480014
  • Nowy Sącz, Poland
    • Investigator Site 0480026
  • Skorzewo, Poland
    • Investigator Site 0480037
  • Toruń, Poland
    • Investigator Site 0480039
  • Warszawa, Poland
    • Investigator Site 0480033
• Portugal
  • Braga, Portugal
    • Investigator Site 3510006
  • Coimbra, Portugal
    • Investigator Site 3510003
  • Lisboa, Portugal
    • Investigator Site 3510002
  • Lisboa, Portugal
    • Investigator Site 3510005
  • Lisboa, Portugal
    • Investigator Site 3510007
  • Porto, Portugal
    • Investigator site 3510001
  • Porto, Portugal
    • Investigator site 3510004
• Romania
  • Bucharest, Romania
    • Investigator Site 0400005
  • Bucuresti, Romania
    • Investigator Site 0400006
  • Bucuresti, Romania
    • Investigator Site 0400009
  • Bucuresti, Romania
    • Investigator Site 0400012
  • Cluj-Napoca, Romania
    • Investigator Site 0400016
  • Craiova, Romania
    • Investigator Site 0400007
  • Sibiu, Romania
    • Investigator Site 0400011
  • Târgu-Mureş, Romania
    • Investigator Site 0400008
• Russian Federation
  • Kaluga, Russian Federation
    • Investigator Site 0070006
  • Kirov, Russian Federation
    • Investigator site 0070040
  • Moscow, Russian Federation
    • Investigator Site 0070026
  • Nizhny Novgorod, Russian Federation
    • Investigator Site 0070038
  • Novosibirsk, Russian Federation
    • Investigator Site 0070037
  • Pyatigorsk, Russian Federation
    • Investigator Site 0070024
  • Saint Petersburg, Russian Federation
    • Investigator Site 0070025
  • Smolensk, Russian Federation
    • Investigator Site 0070039
  • Syktyvkar, Russian Federation
    • Investigator Site 0070015
  • Tula, Russian Federation
    • Investigator Site 0070012
• Serbia
  • Belgrade, Serbia
    • Investigator Site 3810006
  • Kragujevac, Serbia
    • Investigator Site 3810008
• South Africa
  • George, South Africa
    • Investigator Site 0270005
  • Johannesburg, South Africa
    • Investigator Site 0270003
  • Observatory, South Africa
    • Investigator Site 0270004
  • Pretoria, South Africa
    • Investigator Site 0270001
  • Randburg, South Africa
    • Investigator Site 0270002
• Spain
  • Alava, Spain
    • Investigator Site 0340024
  • Barcelona, Spain
    • Investigator Site 0340006
  • Barcelona, Spain, 08035
    • Investigator Site 0340007
  • Barcelona, Spain
    • Investigator Site 0340023
  • Madrid, Spain
    • Investigator Site 0340037
  • Murcia, Spain
    • Investigator Site 0340022
  • Sabadell, Spain
    • Investigator Site 0340036
  • Sevilla, Spain, 41013
    • Investigator Site 0340013
  • Valencia, Spain
    • Investigator Site 0340004
• Taiwan
  • New Taipei City, Taiwan
    • Investigator Site 8860001
  • Taoyuan, Taiwan
    • Investigator Site 8860003
• Thailand
  • Bangkok, Thailand
    • Investigator Site 0660002
  • Bangkok, Thailand
    • Investigator Site 0660003
  • Bangkok, Thailand
    • Investigator Site 0660005
  • Bangkok, Thailand
    • Investigator Site 0660008
  • Bangkok Noi, Thailand
    • Investigator Site 0660001
  • Chiang Mai, Thailand
    • Investigator site 0660004
  • Khon Kaen, Thailand
    • Investigator Site 0660009
  • Pathum Thani, Thailand
    • Investigator Site 0660006
• Tunisia
  • Sfax, Tunisia
    • Investigator Site 2160006
  • Sousse, Tunisia
    • Investigator Site 2160001
  • Tunis, Tunisia
    • Investigator site 2160002
• Turkey
  • Adapazarı, Turkey
    • Investigator Site 0900007
  • Ankara, Turkey
    • Investigator Site 0900003
  • Ankara, Turkey
    • Investigator Site 0900006
  • Ankara, Turkey
    • Investigator Site 0900008
  • Ankara, Turkey
    • Investigator Site 0900015
  • Edirne, Turkey
    • Investigator Site 0900016
  • Istanbul, Turkey
    • Investigator Site 0900013
  • Kocaeli, Turkey
    • Investigator Site 0900014
  • Malatya, Turkey
    • Investigator Site 0900018
  • Mersin, Turkey
    • Investigator Site 0900010
  • Samsun, Turkey
    • Investigator Site 0900009
  • Tekirdağ, Turkey
    • Investigator Site 0900017
  • Trabzon, Turkey
    • Investigator Site 0900019
  • İzmir, Turkey
    • Investigator Site 0900004
• United Kingdom
  • Bradford, United Kingdom, BD9 6RJ
    • Investigator site 0440011
  • Coventry, United Kingdom
    • Investigator Site 0440005
  • London, United Kingdom
    • Investigator Site 0440008
  • London, United Kingdom
    • Investigator Site 0440041
  • Truro, United Kingdom
    • Investigator Site 0440014
• United States
  • Arkansas
    • Springdale, Arkansas, United States, 72758
      • Investigator Site 0010116
  • California
    • Los Angeles, California, United States, 90033
      • Investigator site 0010036
  • District of Columbia
    • Washington, District of Columbia, United States, 20007
      • Investigator Site 0010045
  • Florida
    • Weston, Florida, United States, 33331
      • Investigator Site 0010104
  • Illinois
    • Chicago, Illinois, United States, 60612
      • Investigator site 0010112
    • Chicago, Illinois, United States, 60637
      • Investigator site 0010193
    • Lisle, Illinois, United States, 60187
      • Investigator Site 0010079
  • Indiana
    • Fort Wayne, Indiana, United States, 46804
      • Investigator Site 0010062
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • Investigator Site 0010042
  • Michigan
    • Detroit, Michigan, United States, 48202
      • Investigator Site 0010083
  • Minnesota
    • Minneapolis, Minnesota, United States, 55455
      • Investigator Site 0010102
  • Ohio
    • Columbus, Ohio, United States, 43210
      • Investigator Site 0010040
  • Oklahoma
    • Oklahoma City, Oklahoma, United States, 73142
      • Investigator Site 0010095
  • Pennsylvania
    • Pittsburgh, Pennsylvania, United States, 15222
      • Investigator Site 0010115

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion criteria:

• Ability to understand the requirements of the trial and provide written informed consent, willing and able to comply with the trial protocol procedures
• Is at least the local age of consent for clinical studies when signing the ICF.
• 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
• Diagnosis supported by a response to a prior ITP therapy (other than TPO-RAs), in the opinion of the investigator
• Mean platelet count of <30×10E9/L from at least 3 documented, qualifying counts within the 3 preceding months where at least 2 of the qualifying counts must be taken during the screening period: 1 platelet count collected during the screening period and the predose platelet count on the day of randomization (visit 1). If the third count is not available from the 3 preceding months, this third platelet count can be obtained during the screening period.
• A documented history of a platelet count of <30×10E9/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.

-Agree to use contraceptive measures consistent with local regulations and the protocol

Exclusion criteria:

• 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
• Use of 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
• 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 or Fc fusion proteins, other than those previously indicated, 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
• 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)
• Uncontrolled hypertension, defined as a repeated elevated blood pressure exceeding 160 mmHg (systolic) and/or 100 mmHg (diastolic) despite appropriate treatments
• History of any major thrombotic or embolic event (eg, myocardial infarction, stroke, deep venous thrombosis, or pulmonary embolism) within 5 years prior to randomization
• History of coagulopathy or hereditary thrombocytopenia or a family history of thrombocytopenia
• Evidence of an active clinically significant bleeding of an organ or internal mucosal bleeding, other than expected in ITP, that warrants emergent treatment or therapeutic procedure based on the investigator's judgment (eg, intracranial hemorrhage, pulmonary hemorrhage, bleeding with ongoing need for packed red blood cell transfusion)
• Estimated high risk of a clinically significant bleeding of an organ or internal mucosal bleeding, other than expected in ITP, that warrants emergent treatment or therapeutic procedure according to the investigator's judgment
• 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
• 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, unless associated with a negative HBV DNA test, Hepatitis C virus (HCV) based on HCV-antibody assay (unless associated with a negative HCV RNA test), 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
• Known hypersensitivity reaction to efgartigimod, rHuPH20, or 1 of its excipients
• Previously participated in a clinical trial with efgartigimod and have received at least 1 administration of the IMP
• Pregnant or lactating or intends to become pregnant during the trial
• Clinically significant uncontrolled active or chronic bacterial, viral, or fungal infection at screening
• 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
• 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
• Current or history of (ie, within 12 months of screening) alcohol, drug, or medication abuse
• Received a live/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

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 PH20 SC; Patients receiving efgartigimod PH20 SC treatment	Biological: Efgartigimod PH20 SC; Subcutaneous injection with efgartigimod PH20 SC; Other Names: ARGX-113 PH20 SC
Placebo Comparator: Placebo PH20 SC; Patients receiving placebo PH20 SC treatment	Other: Placebo PH20 SC; Subcutaneous injection with placebo PH20 SC

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of Participants With Chronic Immune Thrombocytopenia (ITP) With a Sustained Platelet Count Response Between Weeks 19 and 24	A participant was considered a responder for this endpoint (i.e., had a sustained platelet count response) if the participant had platelet counts of ≥50 × 10^9/L for ≥4 of the 6 analysis visits between Weeks 19 and 24.	Up to 6 weeks (between Weeks 19 and 24)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Extent of Disease Control Over the 24-Week Treatment Period in the Chronic ITP Population	Extent of disease control was defined as the number of cumulative weeks over the planned 24-week treatment period with platelet counts of ≥50×10^9/L in the chronic ITP population.	Up to 24 weeks
Percentage of Participants in the Overall Population (Chronic and Persistent ITP) With a Sustained Platelet Count Response Between Weeks 19 and 24	A participant was considered a responder for this endpoint (i.e., had a sustained platelet count response) if the participant had platelet counts of ≥50 × 10^9/L for ≥4 of the 6 analysis visits between Weeks 19 and 24.	Up to 6 weeks (between Weeks 19 and 24)
Percentage of Participants in the Overall Population With Sustained Platelet Count Response Between Weeks 17 and 24	A participant was considered a responder for this endpoint (i.e., had a sustained platelet count response) if the participant had platelet counts of ≥50 × 10^9/L for ≥6 of the 8 analysis visits between weeks 17 and 24.	Up to 8 weeks (between Weeks 17 and 24)
Percentage of Participants in the Overall Population Achieving Overall Platelet Count Response at Any Time During the 24-week Treatment Period	A participant was considered a responder for this endpoint (i.e., had an overall platelet count response) if the participant had platelet counts of ≥50 × 10^9/L for ≥4 analysis visits at any time during the 24-week treatment period.	Up to 24 weeks
Extent of Disease Control Until Week 12 in the Overall Population	Extent of disease control was defined as the number of cumulative weeks until Week 12 with platelet counts of ≥50×10^9/L in the overall population.	Up to 12 weeks
Percentage of Participants in the Overall Population Achieving Overall Platelet Count Response at Any Time Until Week 12	A participant was considered a responder for this endpoint (i.e., had an overall platelet count response) if the participant had platelet counts of ≥50 × 10^9/L for ≥4 analysis visits at any time until Week 12.	Up to 12 weeks
Mean Change From Baseline in Platelet Count at Each Visit in the Overall Population	Change from Baseline at time point t = value at time point t - Baseline value. Baseline was defined as the last available value prior to first administration of the investigational medicinal product (IMP).	Baseline and Weeks 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, Safety and Efficacy Follow-up Visit 1 (SEFU1) (up to Week 29), and SEFU2 (up to Week 33)
Time to Platelet Count Response in the Overall Population	Time to platelet count response, defined as the time to have 2 consecutive platelet counts of ≥50 × 10^9/L via Kaplan-Meier estimates.	Up to 24 weeks
Extent of Disease Control Over the 24-Week Treatment Period in the Overall Population	Extent of disease control was defined as the number of cumulative weeks over the planned 24-week treatment period with platelet counts of ≥30×10^9/L with at least ≥20×10^9/L above Baseline in the overall population.	Up to 24 weeks
Extent of Disease Control Over the 24-Week Treatment Period in the Overall Population for Participants With Baseline Platelet Count of <15×10^9/L	Extent of disease control was defined as the number of cumulative weeks over the planned 24-week treatment period with platelet counts of ≥30×10^9/L with at least ≥20×10^9/L above Baseline in the overall population.	Up to 24 weeks
Number of the World Health Organization (WHO)-Classified Bleeding Events (Grade ≥1) in the Overall Population	Assessed using the WHO bleeding scale. The WHO bleeding scale is a five-point scale where Grade 0 = no bleeding; Grade 1 = petechial bleeding; Grade 2 = mild blood loss; Grade 3 = gross blood loss (requires transfusion); and Grade 4 = debilitating blood loss, associated with fatality.	Up to 24 weeks
Percentage of Participants With a Platelet Count International Working Group (IWG) Response	IWG complete response was defined as platelet counts of ≥100 × 10^9/L and the absence of bleeding events (WHO Grading = 0 [no bleeding]) for at least 2 separate, consecutive analysis visits at least 7 days apart. IWG response was defined as platelet counts of ≥30 × 10^9/L and a 2-fold increase of platelet count from Baseline and the absence of bleeding events (WHO grading = 0) for at least 2 separate, consecutive analysis visits that were at least 7 days apart. Initial response was defined as platelet counts of ≥30 × 10^9/L and a 2-fold increase from the Baseline platelet count at analysis visit 5.	Up to 24 weeks
Rate of Receipt of Rescue Therapy (Rescue Per Participant Per Month) in the Overall Population	Rescue therapy was defined as an occurrence where the participant needed treatment with 1 or more rescue treatments. An occurrence was defined as a period of maximum 5 days where 1 or more rescue treatments were administered simultaneously or consecutively to the trial participant. The following rescue treatments were permitted: methylprednisolone, dexamethasone, prednisone, normal immunoglobulins, anti-D (Rho) immunoglobins, or platelet transfusions.	Up to 24 weeks
Percentage of Participants for Whom Dose and/or Frequency of Concurrent ITP Therapies Have Increased at Week 12 or Later in the Overall Population	A change in ITP therapy was defined as either an increase in the dose and/or frequency of a concurrent ITP therapy relative to Baseline or the initiation of a new concurrent ITP therapy.	Up to 13 weeks (between Weeks 12 and 24)
Change From Baseline in Functional Assessment of Chronic Illness Therapy Fatigue Scale (FACIT-Fatigue) at Week 24 in the Overall Population	The FACIT-fatigue scale is a short, 13-item, easy-to-administer tool that measures an individual's level of fatigue during his/her usual daily activities over the past week. The level of fatigue was measured by recording item responses on a 5-point Likert scale ranging from 0 "not at all" to 4 "very much". All items were summed to create a single fatigue score with a range from 0 to 52, where a higher FACIT-F score indicated more severe symptoms. A negative change score from Baseline indicated improvement in quality of life (QoL).	Baseline and Week 24
Change From Baseline in Functional Assessment of Cancer Therapy Questionnaire-Th6 (Fact-Th6) at Week 24 in the Overall Population	The FACT-Th6 uses a 5-level Likert scale (0=not at all to 4=very much), with participants rating their degree of concern in the past 7 days. The 6 selected items pertain to ability to do usual activities, worry about problems with bleeding or bruising, worry about the possibility of serious bleeding, avoidance of physical or social activity because of concern with bleeding or bruising and frustration due to the inability to carry out usual activities. All items were summed to create a single score with a range from 0 to 24, where a higher score indicated less severe symptoms. A positive change score from Baseline indicated improvement in QoL.	Baseline and Weeks 4, 8, 12, 16, 20, and 24
Change From Baseline in Short Form-36 (SF-36) at Week 24 in the Overall Population	The SF-36 is a 36-item scale constructed to survey health-related QoL on 8 domains: limitations in physical activities due to health problems; limitations in social activities due to physical or emotional problems; limitations in usual role activities due to physical health problems; bodily pain; general mental health (psychological distress and well-being); limitations in usual role activities due to emotional problems; vitality (energy and fatigue); and general health perceptions. The scores from the 8 domains were evaluated independently and aggregated into 2 norm-based summary component measures of physical and mental health. The summary component scores could range from 0 to 100, where a higher score indicated improvement in QoL. A positive change score from Baseline indicated improvement in QoL.	Baseline and Week 24
Incidence and Prevalence of Antibodies to Efgartigimod and/or rHuPH20 in the Overall Population	Anti-drug antibody (ADA) incidence was defined as the percentage of participants with treatment-induced or treatment boosted ADA (denominator: number of evaluable participants). ADA prevalence was defined as the percentage of participants with treatment-unaffected ADA, treatment-induced ADA or treatment-boosted ADA (denominator: number of evaluable participants).	Up to 35 weeks
Titers of Antibodies to Efgartigimod and/or rHuPH20 in the Overall Population	A titer was determined in the samples with a positive assay response.	Weeks 3, 7, 11, 15, 19, 23, 24, SEFU1 (up to Week 29), and SEFU2 (up to Week 33)
Incidence and Prevalence of Neutralizing Antibodies (NAb) to Efgartigimod and/or rHuPH20 in the Overall Population	Samples were tested for the presence of NAb against efgartigimod and/or rHuPH20 and titers for NAb against rHuPH20. NAb incidence is defined as the total percentage of participants with participant classification "baseline negative-postbaseline positive" and "baseline positive-postbaseline positive". NAb prevalence is defined as the total percentage of participants with participant classification "baseline negative-postbaseline positive," "baseline positive-postbaseline positive," or "baseline positive-postbaseline negative".	Up to 35 weeks
Serum Efgartigimod Trough Concentration (Ctrough) in the Overall Population	All pharmacokinetic (PK) samples were collected predose, on the day of IMP administration.	Predose on Weeks 1, 2, 3, 17, 19, 21, 23, and 24
Percentage Change From Baseline in Total IgG in the Overall Population	Samples were collected predose, on the day of IMP administration.	Baseline and Weeks 1, 2, 3, 17, 19, 21, 23, and 24
Number of Participants With Antiplatelet Antibodies in the Overall Population	The antiplatelet antibody was positive if optical density value >0.129.	Weeks 7, 15, 23, and 24

Collaborators and Investigators

• Sponsor: argenx

Study record dates

Study Major Dates

• Study Start (Actual): December 16, 2020
• Primary Completion (Actual): October 9, 2023
• Study Completion (Actual): October 9, 2023

Study Registration Dates

• First Submitted: December 18, 2020
• First Submitted That Met QC Criteria: December 23, 2020
• First Posted (Actual): December 29, 2020

Study Record Updates

• Last Update Posted (Actual): October 31, 2024
• Last Update Submitted That Met QC Criteria: October 8, 2024
• Last Verified: October 1, 2024

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; Purpura, Thrombocytopenic, Idiopathic
• Other Study ID Numbers: ARGX-113-2004; 2020-004032-21 (EudraCT Number)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

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