Conference Coverage

Tree nut allergy responds to immunotherapy



ATLANTA – Long-term walnut oral immunotherapy induces clinically relevant treatment response in children with tree nut allergy, results from a small ongoing study showed.

“Tree nut allergy is a generally life-long and potentially life-threatening disorder without an active therapy,” study author Amy M. Scurlock, MD, said in an interview in advance of the annual meeting of the American Academy of Allergy, Asthma, and Immunology. “Significant clinical, immunologic, and serologic cross reactivity has been described among tree nut families. Multi–tree nut allergen sensitization is common with 46% reporting allergy to more than one tree nut.”

Dr. Amy M. Scurlock, University of Arkansas for Medical Sciences, Little Rock

Dr. Amy M. Scurlock

Dr. Scurlock, of the division of pediatric allergy and immunology at the University of Arkansas for Medical Sciences, Little Rock, noted that single-allergen oral immunotherapy has demonstrated efficacy in desensitization to milk, egg, and peanut allergies. The current study, which is ongoing and believed to be the first of its kind, evaluated a novel immunotherapeutic approach to tree nut allergy by using walnut oral immunotherapy, with the goal of inducing not only desensitization to walnuts but also cross-desensitization to a second tree nut. “We wanted to capitalize on cross-reactivity with a goal of desensitizing to more than one tree nut, using single allergen walnut oral immunotherapy,” she explained.

Dr. Scurlock reported on results from 9 of 14 children with allergy to walnuts and another test tree nut (pecans, cashews, hazelnuts, or pistachios) who received open-label walnut oral immunotherapy after completing 38 weeks of blinded, placebo-controlled treatment. Walnut and test tree nut desensitization oral food challenges were performed by 142 weeks. If they passed, the subjects stopped their treatment for four weeks. Next, they underwent another oral food challenge to determine if they continued to be sensitized or if they had developed sustained unresponsiveness.

The median age of the 14 randomized subjects was 9 years, 75% were male, and 9 (64%) underwent an oral food challenge by week 142. (Two subjects dropped out after randomization, and three have yet to reach the week 142 time point.) Desensitization to both walnut and a test tree nut was observed in seven out of the nine subjects (78%). After 4 weeks off of walnut oral immunotherapy, four out of those seven patients who were desensitized (57%) also demonstrated sustained unresponsiveness to both walnuts and test tree nuts, and six out of seven subjects (86%) had sustained unresponsiveness to just walnuts.

“I am always amazed by the commitment of our food allergic subjects and their families in immunotherapy trials, and this study is no exception,” Dr. Scurlock commented. “Subjects had to undergo an increased number of oral food challenges (walnut, test tree nut, placebo) at protocol-specified time points in addition to daily home dosing. While walnut oral immunotherapy was generally well tolerated, we frequently observed oral allergy/itching associated with dosing in our cohort, which was an atopic group (75% allergic rhinitis). These symptoms can complicate assessment during dosing and oral food challenges. We observed that, with long-term therapy, there were some subjects who developed ‘dosing fatigue’ that could adversely affect adherence. Future studies will need to focus on strategies that optimize long-term sustainability/tolerability of dosing.”

She acknowledged certain limitations of the study, including its single-center design and small sample size. “While the findings are encouraging and similar to outcomes observed in other oral immunotherapy trials, further study in larger cohorts is critical before advancing toward broad clinical implementation. Specific issues regarding complexity of cross-reactivity and the efficacy of specific tree nuts to induce immunomodulation across tree nut families require future study. In addition, improving the long-term sustainability/tolerability of dosing and examining novel approaches is important.”

Dr. Scurlock disclosed that she has received funding from National Institutes of Health/National Institute of Allergy and Infectious Diseases and Food Allergy Research and Education (FARE). She is also medical director for the FARE Clinical Network Center of Excellence at Arkansas Children’s Hospital.

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