The purpose of this study is to demonstrate the efficacy and safety of AR101 through reduction in clinical reactivity to peanut allergen in peanut-allergic children and adults.

This is an international, multicenter, randomized, double-blind, placebo-controlled study of the efficacy and safety of AR101 in a characterized desensitization oral immunotherapy regimen in peanut-allergic individuals.

Key Inclusion Criteria:

• Age 4 through 55 years
• Clinical history of allergy to peanuts or peanut-containing foods
• Serum immunoglobulin E (IgE) to peanut ≥0.35 kUA/L (kilos of allergen-specific units per liter, determined by UniCAP™* within the past 12 months) and/or a skin prick test (SPT) to peanut ≥3 mm compared to control
• Experience dose-limiting symptoms at or before the 100 mg challenge dose of peanut protein (measured as 200 mg of peanut flour) on Screening DBPCFC conducted in accordance with PRACTALL** guidelines
• Not be residing at the same address as another subject in this or any peanut OIT study

UniCAP™*: a laboratory system for routine diagnostic testing of allergy and tool for basic studies on allergens and antibodies

PRACTALL**: PRACTical issues in ALLergology Joint United States/European Union Initiative

Key Exclusion Criteria:

• History of cardiovascular disease, including uncontrolled or inadequately controlled hypertension
• History of severe or life-threatening episode of anaphylaxis or anaphylactic shock within 60 days of Screening DBPCFC
• History of chronic disease (other than asthma, atopic dermatitis, or allergic rhinitis) that is, or is at significant risk of becoming, unstable or requiring a change in chronic therapeutic regimen
• History of eosinophilic esophagitis (EoE), other eosinophilic gastrointestinal disease, chronic, recurrent, or severe gastroesophageal reflux disease (GERD), symptoms of dysphagia or recurrent gastrointestinal symptoms of undiagnosed etiology
• History of severe asthma (NHLBI criteria steps 5 or 6), or mild to moderate asthma (2007 NHLBI criteria steps 1-4) that is uncontrolled or difficult to control
• History of steroid medication use
• History of a mast cell disorder, including mastocytosis, urticarial pigmentosa, and hereditary or idiopathic angioedema
• Developing dose-limiting symptoms in reaction to the placebo part of the Screening DBPCFC
• Having the same place of residence as another subject in the study