This is a phase 2a, multi-center, randomized and double-blind placebo-controlled trial comparing 24 weeks of abatacept versus placebo used as adjuvant to oral immunotherapy to induce remission in adolescents and adults with persistent severe peanut allergy.

This is a proof-of-concept trial in which the primary outcome will be the suppression of the initial peanut specific IgE surge during OIT, which is used as a proxy outcome of peanut allergy remission.

Adolescents and adults with persistent severe peanut allergy (n=14) will be randomized to either abatacept or placebo at a ratio 1:1 for a total period of 24 weeks. Peanut oral immunotherapy will be initiated the day following the first administration of the investigational product. Sustained tolerance to peanut will be assessed at 36 weeks.

Inclusion Criteria:

• Male or female subjects 14 to 50 years old at screening visit
• History of IgE mediated allergy to peanut protein
• ImmunoCAP IgE level > 50 kU/L for peanut;
• Total IgE level < 5000 kU/L
• Willing to comply to all study requirements during participation in the study;

Exclusion Criteria:

• Previous adverse reactions to abatacept;
• Known hypersensitivity to abatacept or any of its components;
• Patients at risk of sepsis, such as immunocompromised or HIV positive;
• Patient undergoing a treatment with any other biologic agent;
• Uncontrolled asthma;
• Unstable angina, significant arrhythmia, uncontrolled hypertension, chronic sinusitis, or other chronic or immunological diseases that, in the judgment of the investigator, might interfere with the evaluation, administration of the test drug or pose additional risk to the subject (e.g., gastrointestinal or gastroesophageal disease, chronic infections, scleroderma, hepatic and gallbladder disease, chronic non-allergic pulmonary disease);
• Current users of oral, intramuscular, or intravenous corticosteroids, tricyclic antidepressants or beta-blocker
• Concurrent/prior use of immunomodulatory therapy (within 6 months);
• A diagnosis of eosinophilic esophagitis, eosinophilic colitis, or eosinophilic gastritis;
• Pregnant or breastfeeding women;