Jim Kling

March 07, 2016

LOS ANGELES — Infants at high risk of developing peanut allergy who are introduced to peanuts during their first 5 years continue to show tolerance, even after a 12-month abstinence from peanuts, according to an extension of the practice-changing Learning Early About Peanut Allergy (LEAP) trial.

The results of the study, known as LEAP-On, were presented here at the American Academy of Allergy, Asthma and Immunology 2016 Annual Meeting, and published online simultaneously in the New England Journal of Medicine.

"We have prevented peanut allergy in children, so far," said Gideon Lack, MD, professor of pediatric allergy at King's College London in the United Kingdom, during a news conference. The researchers plan to continue observing the children in their epidemiologic study until they are 10 years of age.

The results are important because people receiving such immunotherapy often have a relapse of sensitivity if they stop the treatment.

"When all immunotherapies are applied as a treatment modality, after a period of sustained tolerance — whether that was 1 month, 2 months, or 3 months — a high proportion of children revert to being clinically reactive on challenge. The question in our minds was, is this a sustained, long-term effect?" Dr Lack explained.

We have prevented peanut allergy in children, so far.

"The question was legitimate as to whether we had just transiently desensitized the children or whether they had achieved longer lasting tolerance," he added.

The initial LEAP study involved infants (median age, 7.8 months) with severe eczema or egg allergy who were randomized to receive at least 6 g of peanut protein at three or more meals per week until they turned 5, or to avoid peanuts.

For the 530 children who initially tested negative for peanut allergy in LEAP, the incidence of allergy at the age of 5 was lower in those who consumed peanut protein than in those who avoided it (1.9% vs 13.7%; P < .001). The same pattern was seen for the 98 children who initially tested positive for peanut allergy (10.6% vs 35.3%; P < .004).

LEAP-On Extension Study

In LEAP-On, 556 (88.5%) of the 5-year-old LEAP subjects were instructed to abstain from peanuts for 1 year. Abstinence rates — determined through questionnaires and analysis of peanut protein in dust collected from the children's beds — were high in the consumption and avoidance groups (69.3% vs 90.4%).

But it was no surprise to the researchers that the rate of abstinence was lower in the consumption group than in the avoidance group; it can be a difficult adjustment for a 5-year old to give up a food he or she is used to eating.

"That was a huge altruistic measure on their part," said LEAP-On coauthor George Du Toit, MB BCh, a consultant in children's allergy at Evelina London Children's Hospital and the Portland Hospital in London, United Kingdom.

In the consumption group, there was no significant difference in peanut allergy between the preabstinence period, when the children were 60 months of age, and the postabstinence period, when the children were 72 months of age (3.6% vs 4.8%; P = .25).

During the 12-month abstinence period, there were three new cases of peanut allergy in each group.

At 72 months, the incidence of peanut allergy was significantly higher in the avoidance group than in the consumption group (18.6% vs 4.8%, P < .001).

We were looking for the home run that we got.

Daniel Rotrosen, MD, director of the division of allergy, immunology, and transplantation at the National Institute of Allergy and Infectious Disease, which partially funded this study, was effusive about the results. "We were looking for the home run that we got," he told reporters attending the news conference.

Others also praised the results. "It is very reassuring that the protection the babies got during the first 5 years seems to have had a permanent effect on their immunologic status," Larry Posner, MD, an allergist and immunologist from Napa, California, told Medscape Medical News.

Dr Lack, Dr Du Toit, and Dr Posner have disclosed no relevant financial relationships. Dr Rotrosen is an employee of the National Institute of Allergy and Infectious Disease, which funded the study.

American Academy of Allergy, Asthma and Immunology (AAAAI) 2016 Annual Meeting. Presented March 4, 2016.


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