The study is designed to assess the efficacy and safety of anakinra, an interleukin 1 receptor antagonist, in patients with Kawasaki disease who failed to respond to standard treatment:e.g. one infusion of 2g/kg of intravenous immunoglobulins.

Kawasaki disease (KD), is the most frequent vasculitis in children before 5 years, and the main cause of acquired cardiomyopathy in adulthood. The prognosis of KD is influenced by early recognition and treatment by intravenous immunoglobulins (IVIG), which represent the standard of care and decrease significantly the risk of coronary aneurysms. Despite a first infusion of IVIG, 20% of KD patients remain febrile and are at high risk of coronary vasculitis. To date there is no agreement for a more effective second line treatment. On the basis of the autoinflammatory pattern of KD, we hypothesize that anti IL-1 blocking agents could bring a rapid and sustained effect on systemic and coronary inflammation in patients with KD.

Aim of the study

• To assess the efficacy of anakinra (IL-1R1receptor antagonist) in patients with KD who fail to respond to one infusion of IVIg (standard treatment).
• To assess the efficacy of anakinra on disease activity
• To assess the efficacy of anakinra on coronary lesions (eg: dilatation and aneurysm
• To assess the safety and tolerability of anakinra Patients and methods A Proof of concept (quasi experimental, non randomized cohort) study. This is a 3-year open-label, prospective multicenter trial of Anakinra in patients with acute KD who failed to respond to a first infusion of IVIG within 48h. Patients will be eligible to enter the study if they have persistence (or recrudescence of fever) within 48 hours after the infusion of IVIg, and if they have given their informed consent to enter the study. After appropriate screening, the study treatment will be initiated between J7 and J14 days of illness to expect full clinical effect. The only primary endpoint will be the absence of fever after 48 h of treatment (assessed at J3 of study treatment, visit 3, before the third injection of anakinra). If the patient remains febrile (fever >38°C), he will receive a double dose of anakinra (4mg/kg) at day 3 instead of 2mg/kg. Treatment will be continued until they have achieved complete response as defined in the outcome measurement section, and during a maximum of 15 days.

Expected results and expected public health benefit Anakinra treatment is expected to reduce the early and long term mortality of patients with KD, by a rapid and sustained effect on vascular inflammation. The safety of anakinra is expected to be good, as the drug has a very short half-life, which allows its rapid withdrawal in case of serious adverse event. The use of anakinra, is not associated with the risk of contamination by infectious agents, which remains even minimal, a possibility with the use of IVIG

Inclusion Criteria:

• Patients, male and female, at any age ≥ 3 months (5 kg) of life, with KD according to the American Heart Association definition for complete or incomplete KD. fever ≥ 5 days and ≥ 4 of 5 main clinical signs: modification of the extremities, polymorphic exanthema, bilateral bulbar not exudative conjunctivitis, erythema of the lips or oral cavity, and cervical lymph nodes usually unilateral > 1.5 cm in diameter. In the presence of less than 4 clinical criteria and 5 days of fever, the diagnosis of disease KD is proposed in case of coronary abnormalities (at least one dilated coronary artery with internal diameter ≥ 2,5 SD from the mean normalized for body surface area (Z score) as determined by echocardiography. For indicative purpose, in case of incomplete KD, other biological supportive criteria for incomplete KD can help to ensure the diagnosis: leucocytosis, elevated CRP, elevated ESR, anaemia, hyponatremia, elevated ASAT, ALAT and gGT, hyperlipidaemia.
• Patients who failed to respond to standard therapy of KD:, e.g. Persistence or recrudescence of fever ≥ 38°C, 48 hours after the infusion of 2g/kg of IV Ig,
• Weight ≥5Kg
• Patient, parent or legal guardian's written informed consent is required
• Patient with health insurance
• Patient agrees to have effective contraception for the duration of participation in the research

Exclusion Criteria:

• Preterm and neonates, pregnancy

• Patients suspected with another diagnosis

• Patients with overt concomitant bacterial infection

• Patients previously treated with another biotherapy

• Patients with any type of immunodeficiency or cancer

• Patients with increased risk of TB infection

• Recent tuberculosis infection or with active TB

  • Close contact with a patient with TB
  • Patients recently arrived less than 3 months from a country with high prevalence of TB
  • A chest radiograph suggestive of TB

• Patients with end stage renal disease: NKF stages ≥4; eGFR≤29mL/min/1.73 m2 or diabetes mellitus or neutropenia <1500/mm3 or liver failure

• Hypersensitivity to the active substance or to any of the excipients (citric acid and anhydrous; sodium chloride disodium edetate dehydrate polysorbate 80; sodium hydroxide; water for injections)

• Patient already included in a biomedical research other than observational (e.g.; cohort, registry)