Potential Breakthrough for Children With Peanut Allergies
A pilot study from Boston Children's Hospital's Division Allergy and Immunology and Harvard Medical School shows that desensitizing peanut allergic patients through increased peanut exposure, in tandem with an allergy drug called omalizumab (Xolair, anti-IgE monoclonal antibody, Genentech), allowed 13 children with significant peanut allergies to build up resistance quickly with limited allergic reactions. The findings were published online October 30 by the Journal of Allergy and Clinical Immunology.
Peanut allergy is a major public health problem affecting 1 to 2 percent of the population in most Western countries, with as many as 80 to 95 percent of all allergy-related deaths due to peanut exposure. Currently, there is no effective therapy for peanut allergy aside from avoidance and having ready access to epinephrine in the event of accidental exposure.
Based on a treatment protocol for milk allergies developed by Boston Children's in 2010, Dale Umetsu, MD, PhD, Rima Rachid, MD, and Lynda Schneider, MD, theorized that combining treatment with the drug omalizumab and desensitization—which exposes peanut allergic patients to trace amounts of the nut in a controlled medical environment—would reduce the frequency of allergic reactions, greatly facilitating acceptance of treatment. This method has previously shown to be effective in those with milk allergies.
Thirteen peanut allergic children were enrolled in the study. They were chosen because each was at high risk for developing significant allergic reactions, even from exposure to just a small amounts of peanuts.
"Previous research shows patients with severe peanut allergies have historically been resistant to oral food desensitization," Umetsu says. "We believed that if this protocol could prove successful with a high-risk population, it could have far-reaching implications for the peanut allergy community as a whole."
After failing a double-blind placebo controlled food challenge at doses of <100 mg peanut flour (about one-quarter of a peanut), participants received omalizumab injections for three months. After this pretreatment, all 13 subjects tolerated an initial 11 desensitization doses, including the maximum dose of 500 mg peanut flour (about two peanuts), requiring minimal or no rescue therapy.
For the next eight weeks, subjects tolerated doses of 4,000 mg peanut flour, at which point omalizumab was discontinued. By the time the year-long study had concluded, 12 of the 13 participants, (one patient left the study during the fifteenth week due to persistent nausea and vomiting), were tolerating the equivalent of 20 peanuts a day, most without receiving any additional medication apart from the occasional anti-histamine.
A total of 72 reactions were recorded during the course of the study, with 25 occurring in one patient who had an additional medical condition. Most of the reactions were mild, consisting of nausea and excessive saliva production, and were easily treated with observation or an antihistamine. There were three cases where an anaphylactic reaction required epinephrine.
"As demonstrated by this initial study, treatment with omalizumab may facilitate rapid oral desensitization even among children with high-risk peanut allergy," Rachid says. "If these findings are confirmed with larger double-blind, placebo-controlled studies, the process of using omalizumab to facilitate oral desensitization could potentially change the clinical approach for a large number of patients living with peanut allergies."