AR101 is an investigational biologic drug being developed for use during oral immunotherapy to reduce the incidence and severity of allergic reactions following exposure to peanuts. Its Biologics License Application is under review by the FDA, which granted it Breakthrough Therapy Designation in 2015 for the desensitisation of peanut-allergic patients 4 to 17 years of age. The European Medicines Agency is reviewing the Marketing Authorization Application for AR101 which was submitted in June 2019.