Published Online: Sept 6, 2016
Peanut allergy is a potentially life-threatening condition but there are no approved curative therapies. A major focus of current research is the development of new treatments to change the allergic immune response and protect peanut-allergic patients against accidental exposure to the allergen. Oral immunotherapy (OIT) is one of the more promising new treatments and involves daily oral ingestion of a controlled dose of peanut protein. The gradual increase in the dose over time creates a state of desensitization intended to protect against accidental ingestion of peanut. Multiple studies have now shown OIT to be efficacious at desensitizing peanut-allergic children, but this efficacy comes at the expense of high rates of allergic adverse events (AEs), and the risk/benefit ratio of OIT is an area requiring more study.
In a recently published article in The Journal of Allergy & Clinical Immunology (JACI), Virkud and colleagues studied the frequency OIT-associated AEs and study withdrawals, and identified baseline features that may characterize subjects at higher risk for AEs. The authors pooled safety data from 104 subjects in three trials performed by the same group, with maintenance doses ranging from 300 to 4000 mg/day. AEs were catalogued from parental report, daily symptom diaries, and dose escalation visits. Using generalized linear regression analysis, the team then examined potential clinical characteristics (sex, age, presence of other allergic diseases, peanut Immunoglobulin E level, or peanut skin prick test size) for associations with higher AE rates.
While on OIT, 80% of subjects experienced likely-related AEs during OIT, with higher rates during buildup compared to maintenance, and most (over 90%) occurred while at home, consistent with daily exposure to study product. Most events were mild, but approximately 42% of subjects experienced systemic reactions potentially consistent with anaphylaxis, and 49% experienced gastrointestinal symptoms. Twenty percent of subjects withdrew from the trials, with 13 patients developing new or worsening symptoms on OIT and 10 of these patients (10% of overall group) withdrawing due to persistent gastrointestinal symptoms. Allergic rhinitis in particular was associated with almost three times as high rates of AEs, even after adjusting for the asthma and peanut skin test, and this finding was supported by higher rates of AEs over the spring and fall months. Allergic rhinitis was also associated with greater rates of systemic reactions, and size of skin prick test was associated with greater rates of gastrointestinal symptoms. Over the course of OIT (up to a maximum of 6 years for some patients), 61% of subjects received treatment for likely-related AEs, 59% with antihistamines and 12% with epinephrine.
Overall, peanut OIT is associated with frequent AEs, with rates declining over time, and most graded mild. However, systemic reactions and intolerable gastrointestinal AEs do occur and are significantly associated with allergic rhinitis and peanut skin test, respectively. This analysis suggests that larger peanut skin prick tests, the presence of allergic rhinitis, and asthma may be useful in identifying patients who will have more AEs and potentially more risk while on OIT. Although OIT is a promising investigational therapy with the potential to improve food allergy associated mortality and quality of life, there remain a number of important safety variables that are both problematic and poorly understood. Additional studies are needed in order to weigh the substantial potential benefits of OIT against the risks of allergic AEs.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.