Efficacy and Safety of Immunoglobulin Plus Firsekibart in Patients With Kawasaki Disease

Efficacy and Safety of Immunoglobulin Plus Firsekibart in Patients With Kawasaki Disease: An Exploratory Randomized Controlled Study

This study evaluates the efficacy and safety of the addition of Firsekibart to conventional initial treatment (intravenous immunoglobulin [IVIG] plus aspirin) in children with Acute Kawasaki Disease (KD) .

Study Overview

• Status: Not yet recruiting
• Conditions: Kawasaki Disease
• Intervention / Treatment: Drug: IVIG; Drug: Aspirin; Drug: Firsekibart

Detailed Description

This is a two-center, open-label, randomized controlled exploratory clinical trial in China. The investigators will enroll KD pediatric patients within 10 days of illness onset. Participants will be randomly assigned in a 1:2 ratio to the experimental group (receiving 3 mg/kg Firsekibart plus 2 g/kg IVIG and 30 mg/kg aspirin) or the control group (receiving 2 g/kg IVIG and 30 mg/kg aspirin). Baseline characteristics of each participant will be collected, including sex, age at onset, height, body weight, subtype of KD, fever days before initial IVIG, echocardiographic findings at enrolment, and a series of pre-IVIG laboratory tests. Two-dimensional echocardiography will be performed at admission, 2 weeks, 1 month, 3 months, and 6 months after illness onset to assess the coronary artery lesions. This study aims to determine the therapeutic potential of standard therapy combined with Firsekibart in the acute phase of KD for reducing the incidence of coronary artery lesions (CAL) , decreasing IVIG resistance, and improving inflammation control.

• Study Type: Interventional
• Enrollment (Estimated): 90
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Fang Liu, MD; Phone Number: +86 021-64932800; Email: liufang@fudan.edu.cn
• Study Contact Backup: Name: Lan He, MD; Phone Number: +8602164932026; Email: helan0361@163.com

Study Locations

• China
  • Jiangxi
    • Nanchang, Jiangxi, China, 330006
      • Jiangxi Provincial Children's Hospital
      • Contact: Xiaohui Liu, MD
  • Shanghai Municipality
    • Shanghai, Shanghai Municipality, China, 201102
      • Children's Hospital of Fudan University
      • Contact: Fang Liu, MD

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Meeting diagnostic criteria for Kawasaki disease (KD) released by American Heart Association (AHA) in 2024
2. Diagnosed before the tenth day of illness (with the first day of illness defined as the first day of fever)
3. Not treated with IVIG yet
4. Age >28 days，<18 years

Exclusion Criteria:

1. Receiving steroids or other immunosuppressive agents in the previous 30 days;
2. With a previous history of KD;
3. Afebrile before enrolment;
4. Contraindications for subcutaneous injection, including severe local skin infection, ulceration, etc;
5. Known hypersensitivity to immunoglobulins, Firsekibart, or any of the excipients;
6. With suspected infectious diseases including sepsis, septic meningitis, peritonitis, bacterial pneumonia, varicella, influenza, active tuberculosis, hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), and cytomegalovirus (CMV) infection ;
7. With serious immune diseases, such as immunodeficiency, or chromosomal abnormalities;
8. With severe hepatic dysfunction (ALT > 3 times the upper limit of normal) prior to treatment
9. Unwillingness to provide written informed consent;
10. Unlikely to complete at least 3 months of follow-up;
11. Any other conditions deemed unsuitable for enrolment by investigators.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: standard treatment group; 【Standard treatment follow the 2024 AHA Guidelines of Kawasaki Disease】; IVIG 2g/kg once, given within 8 to 12 hours;; Aspirin 30 mg/kg in oral per day (given in 3 divided doses), then 3 to 5 mg/kg per day when fever subsides for 3 days and C-reactive protein (CRP) is normal. Aspirin will be continued for at least 6 weeks after illness onset. Participants with persistent or recurrent fever (temperature of ≥38°C ) 36 hours after completion of the first IVIG infusion are defined as having resistance to IVIG and will receive rescue therapy. The rescue therapy will be chosen on the basis of participant's condition and the physician's experience. Participants intolerant to aspirin may receive oral clopidogrel as an alternative. In the event of a Grade ≥3 allergic reaction, the treatment will be discontinued immediately, and epinephrine will be administered.	Drug: IVIG; IVIG 2g/kg once, given within 8 to 12 hours, with the maximum dose of 60g.; Other Names: Intravenous Immunoglobulins, Human; Drug: Aspirin; Aspirin 30 mg/kg in oral per day (given in 3 divided doses), then 3 to 5 mg/kg per day when fever subsides for 3 days and CRP is normal. Aspirin will be continued for at least 6 weeks after onset of illness.; Other Names: Acetylsalicylic acid
Experimental: Firsekibart + standard treatment group; Firsekibart 3 mg/kg by a single subcutaneous injection prior to IVIG infusion. After a 30-minute observation period confirming the absence of adverse reactions, the IVIG infusion is initiated.; IVIG 2g/kg once, given within 8 to 12 hours;; Aspirin 30 mg/kg in oral per day (given in 3 divided doses), then 3 to 5 mg/kg per day when fever subsides for 3 days and CRP is normal. Aspirin will be continued for at least 6 weeks after onset of illness. 【Standard treatment also follow the 2024 AHA Guidelines of Kawasaki Disease】 Discomfort occurring during the observation period after Firsekibart will be treated symptomatically, and standard treatment will subsequently be provided as needed based on the participant's condition and the physician's experience. Management of IVIG resistance, aspirin intolerance , and allergic reaction will be the same as in the control group.	Drug: IVIG; IVIG 2g/kg once, given within 8 to 12 hours, with the maximum dose of 60g.; Other Names: Intravenous Immunoglobulins, Human; Drug: Aspirin; Aspirin 30 mg/kg in oral per day (given in 3 divided doses), then 3 to 5 mg/kg per day when fever subsides for 3 days and CRP is normal. Aspirin will be continued for at least 6 weeks after onset of illness.; Other Names: Acetylsalicylic acid; Drug: Firsekibart; Firsekibart 3 mg/kg by a single subcutaneous injection prior to IVIG infusion. After a 30-minute observation period confirming the absence of adverse reactions, the IVIG infusion is initiated.; Other Names: Interleukin (IL)-1β receptor antagonist

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Occurrence of coronary artery lesions (CAL) at one month of illness	Two-dimensional echocardiography will be performed to evaluate CAL at 1 month of illness. Measurements for each patient include the diameter of the left main coronary artery (LMCA), the left anterior descending artery (LAD), the left circumflex coronary artery (LCX), and the proximal and middle segments of the right coronary artery (RCA). Z score of each coronary artery will be calculated (Journal of the American Society of Echocardiography, 2011, 24(1).). CAL is defined as z≥2.5 of any coronary artery of LMCA, LAD, LCX, and the proximal and middle segment of the RCA.	from admission to 1 month of illness onset
Occurrence of the need for rescue therapy	Temperature will be measured every 6 hours a day during hospitalization. Participants who have recurrent or persistent fever (temperature ≥38°C) after 36 hours of completion of initial IVIG infusion will be given rescue therapy.	from admission to discharge (about 2 weeks of illness onset)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Duration of fever (hours) after initiation of initial IVIG infusion	Temperature will be measured every 6 hours a day during hospitalization. Participants with temperature <37.5℃ for more than 24 hours are considered afebrile. Record the time of the initiation of IVIG infusion and the time of the body temperature first becoming normal.	from initiation of the initial IVIG infusion to the first recorded afebrile status (up to 60 hours after the infusion of IVIG)
Change in serum C-reactive protein (CRP) concentration	Serum CRP levels will be measured at four time points: at enrolment, 72 hours after completion of the initial IVIG infusion, and 2 weeks and 1 month of illness onset.	from admission to 1 month of illness onset
Change in Serum Amyloid A (SAA) concentration	SAA levels will be measured at four time points: at enrolment, 72 hours after completion of the initial IVIG infusion, and 2 weeks and 1 month of illness onset.	from admission to 1 month of illness onset
Change in serum interleukin (IL)-1β concentration	Serum IL-1β levels will be measured at four time points: at enrolment, 72 hours after completion of the initial IVIG infusion, and 2 weeks and 1 month of illness onset.	from admission to 1 month of illness onset
Occurrence of coronary artery lesions (CAL) at 2 weeks of illness	Two-dimensional echocardiography will be performed to evaluate CAL at 2 weeks of illness. The measurement of each patient included the diameter of the left main coronary artery (LMCA), the left anterior descending artery (LAD), the left circumflex coronary artery (LCX), and the proximal and middle segments of the right coronary artery (RCA). Z score of each coronary artery will be calculated (Journal of the American Society of Echocardiography, 2011, 24(1).). CAL is defined as z≥2.5 of any coronary artery of LMCA, LAD, LCX, and the proximal and middle segment of the RCA.	from admission to 2 weeks of illness onset
Occurrence of coronary artery lesions (CAL) at 3 months of illness	Two-dimensional echocardiography will be performed to evaluate CAL at 3 months of illness. Measurements for each patient include the diameter of the left main coronary artery (LMCA), the left anterior descending artery (LAD), the left circumflex coronary artery (LCX), and the proximal and middle segments of the right coronary artery (RCA). Z score of each coronary artery will be calculated (Journal of the American Society of Echocardiography, 2011, 24(1).). CAL is defined as z≥2.5 of any coronary artery of LMCA, LAD, LCX, and the proximal and middle segment of the RCA.	from admission to 3 months of illness onset
Occurrence of medium-to-giant coronary artery aneurysms (CAAs)	This is a repeatedly measured binary variable. CAL classification is based on the maximum Z score according to the 2024 American Heart Association guideline. Medium CAAs is defined as a maximum Z score ≥5 to <10, and all internal diameters <8 mm; large or giant CAAs defined as a maximum Z score ≥10, or any internal diameter ≥8 mm.	from admission to 6 months of illness onset
Changes in z scores of LAD	This is a repeated measurement. The internal diameter of LAD will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months of illness. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Changes in z scores of LMCA	This is a repeated measurement. The internal diameter of LMCA will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months of illness. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Changes in z scores of LCX	This is a repeated measurement. The internal diameter of LCX will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months of illness. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Changes in z scores of the proximal segment of RCA	This is a repeated measurement. The internal diameter of the proximal segment of RCA will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months of illness. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Changes in z scores of the middle segment of RCA	This is a repeated measurement. The internal diameter of the middle segment of RCA will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months of illness. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Occurrence of CAL regression	CAL regression is defined as Z score <2.5 in any coronary artery (LMCA, LAD, LCX, and the proximal and middle segments of the RCA), with no stenotic or occlusive lesions present.The internal diameter of the coronary artery will be measured by echocardiography at five time points: at enrolment, at 2 weeks, 1 month, 3 months and 6 months after illness onset. Z score will be calculated based on the height, weight and coronary artery diameter (Journal of the American Society of Echocardiography, 2011, 24(1).).	from admission to 6 months of illness onset
Occurrence of CAL progression	CAL progression is defined as an increment in the Z score >1 from admission in any coronary artery (LMCA, LAD, LCX, proximal and middle segments of RCA) at any given time point within 6 months of illness onset. The outcome will be assessed in all participants and those with CAL at baseline.	from admission to 6 months of illness onset
Occurrence of adverse events	This is a composite outcome, including (a) clinical adverse events (death, severe infection, allergic reactions, heart failure, and thrombosis); (b) laboratory abnormalities (neutropenia, defined as <1.5×10⁹/L; thrombocytopenia, defined as <100×10⁹/L; newly developed ALT abnormality after medication, or further elevation of abnormal baseline ALT); (c) infectious events (occurrence of bacterial/viral infections); and (d) injection-site allergic reactions (redness and swelling at the injection site, rash, and anaphylactic shock) , etc.	from admission to 6 months of illness onset

Collaborators and Investigators

• Sponsor: Children's Hospital of Fudan University
• Collaborators: Jiangxi Province Children's Hospital
• Investigators: Study Director: Fang Liu, MD, Children's Hospital of Fudan University

Study record dates

Study Major Dates

• Study Start (Estimated): August 1, 2026
• Primary Completion (Estimated): September 1, 2027
• Study Completion (Estimated): February 1, 2028

Study Registration Dates

• First Submitted: June 26, 2026
• First Submitted That Met QC Criteria: July 6, 2026
• First Posted (Actual): July 7, 2026

Study Record Updates

• Last Update Posted (Actual): July 7, 2026
• Last Update Submitted That Met QC Criteria: July 6, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Kawasaki Disease; Firsekibart; Coronary Artery Lesion
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Skin Diseases; Lymphatic Diseases; Skin Diseases, Vascular; Vasculitis; Skin and Connective Tissue Diseases; Hemic and Lymphatic Diseases; Mucocutaneous Lymph Node Syndrome; Peptides; Amino Acids, Peptides, and Proteins; Proteins; Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Biological Factors; Hydrocarbons, Aromatic; Antibodies; Immunoglobulins; Immunoproteins; Blood Proteins; Serum Globulins; Globulins; Phenols; Benzene Derivatives; Intercellular Signaling Peptides and Proteins; Immunoglobulin Isotypes; Immunoglobulin G; Salicylates; Hydroxybenzoates; Cytokines; Aspirin; Immunoglobulins, Intravenous; Interleukins
• Other Study ID Numbers: 2026-244

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