Oral Immunotherapy Protocol Induces Tolerance in Some Peanut-Allergic Children

Neil Osterweil

March 19, 2009

March 19, 2009 (Washington, DC) — The news that peanut-allergic children could eventually tolerate peanuts through a gradual oral immunotherapy protocol was splashed across the headlines and was the lead story on many TV newscasts this week.

Lost in all the hoopla was the fact that the studies involved only about 50 children, that the therapy was delivered only under close medical supervision, and that the protocol is still investigational. Although 5 of 33 children diagnosed as peanut-sensitive are now able to eat peanuts as part of their regular diet, 4 dropped out because of allergic reactions deemed too worrisome by parents and/or investigators.

In other words, parents of peanut-allergic children should be cautioned, "Don't try this at home," said Wesley Burks, MD, professor and chief of pediatric allergy and immunology at Duke University Medical Center in Durham, North Carolina.

US Food and Drug Administration approval of oral immunotherapy is likely to be at least a decade away, Dr. Burks added here at the 2009 annual meeting of the American Academy of Allergy, Asthma and Immunology.

Under the protocol used at Duke and at Arkansas Children's Hospital in Little Rock, peanut-sensitive children are exposed on day 1 to 0.1 mg of peanut flour, and the dose is then doubled every 30 minutes to a maximum of 50 mg. This is followed by a build-up phase in which doses are increased by 25 mg every 2 weeks until 300 mg is reached, followed by a maintenance, daily home-dose phase.

Three study cohorts were planned, and 1 has been completed. In cohort 1, 14 patients received a 300-mg dose daily for 24 months. In cohort 2, 15 patients are assigned to receive 2000 mg daily, and in cohort 3, 20 patients are scheduled to receive 4000 mg in a blinded, placebo-controlled study.

After the maintenance phase, children are given 3900 mg of peanut protein (equivalent to about 13 peanuts) in an oral food challenge.

At the time of the data presentation, 29 of 33 children had completed the study at at both sites; 4 children dropped out because of allergic adverse effects.

The mean age at enrollment was 57 months (range, 12 – 111 months), and the mean age at first reaction was 15 months (range, 8 – 48 months).

Associated conditions included atopic dermatitis in 69%, asthma in 62%, and allergic rhinitis in 62%.

In the peanut challenges, 27 of the 29 patients were able to ingest from 300 to 3900 mg peanut protein. One patient had mild transient early symptoms but still managed to ingest the 3900-mg dose at challenge, and 1 had allergic symptoms (1 hive and sneezing), leading to the challenge being stopped at 2100 mg at the parent's request.

The authors also looked at peanut-specific immunoglobulin E and found that although the levels dropped in all children, the decrease was most rapid in those children who were able to eat peanuts without developing symptoms.

In the placebo-controlled portion of the study, 12 children received peanut powder and 6 received placebo and were challenged after 10 months. Children on placebo developed allergic symptoms after a mean of about 1.5 peanuts, whereas those in the active treatment group could tolerate about 15 peanuts. This portion of this study is ongoing, with a total enrolment of 80 planned, Dr. Burks said.

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