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Background: Oral immunotherapy containing peanut (Arachis hypogaea) allergen powder-dnfp (PTAH) (Palforzia [Aimmune Therapeutics, Brisbane, Calif]) for 9 to 12 months resulted in higher tolerated amounts of peanut protein in PTAH-treated individuals aged 4 to 17 years with peanut allergy than in placebo-treated participants. Objective: We aimed to describe additional long-term pooled safety data and changes in peanut sensitization markers from baseline through approximately 5 years of treatment. Methods: The results from 6 clinical trials of PTAH (3 controlled and 3 open-label extension studies [N = 1227]) were pooled, and analysis of safety outcomes and immunologic data was performed. The PTAH doses were administered sequentially as follows: initial dose escalation (dose increased to 6 mg over 2 days), updosing (dose increased every 2 weeks to 300 mg for a minimum of 6 months), and maintenance dosing (300 mg per day). Results: There was a trend toward decreased adverse events (AEs) at years 1 and 2 that was maintained up to 5 years, with 94% of patients experiencing mild or moderate AEs and only 13% discontinuing PTAH use because of AEs overall. Gastrointestinal symptoms were the most commonly reported treatment-related AEs. A downward trend in systemic allergic reactions was also reported. PTAH treatment resulted in reduced levels of peanut-specific IgE after the first year and increased levels of peanut-specific IgG4, with a lowered peanut-specific IgE:IgG4 ratio. A reduction in median peanut skin prick test wheal diameter was observed (11.50 mm at baseline vs 5.75 mm at year 5). Conclusion: Long-term immunomodulation without any new safety signals was reported with PTAH immunotherapy in the largest safety data set and longest treatment duration for oral immunotherapy published to date.