ATLANTA (FRONTLINE MEDICAL NEWS) – One year or more after peanut immunotherapy, 27 of 33 (82%) children were eating peanuts regularly, most without problems, in a survey from the Children’s Hospital of Philadelphia.

The finding speaks to the durability of peanut immunotherapy, something that’s been a concern for physicians and families. It suggests that peanut immunotherapy might give children long-term protection from accidental exposure, so long as they continue to eat a small amount of peanut almost every day after desensitization.

However, four children (12%) who ate more than one peanut a day had anaphylactic reactions that required epinephrine. The right maintenance dose after peanut allergy treatment isn’t known, but perhaps one peanut a day (300 mg) is enough. Eating more than that might increase the risk of reaction, lead investigator and pediatric nurse practitioner Megan T. Ott Lewis , the food allergy research program manager at the Children’s Hospital of Philadelphia, reported at the annual meeting of the American Academy of Asthma, Allergy, and Immunology.

She and her team surveyed the families of 15 children who completed a trial of epicutaneous peanut immunotherapy (EPIT) and 9 who completed a trial of oral immunotherapy (OIT) about a year after the studies ended. They also surveyed families of nine children about 2 years after they completed a trial of OIT plus omalizumab (Xolair) for peanut allergy. The investigators and families chose maintenance doses based on results from the final peanut challenges, and children were warned against running around within 2 hours of their dose, to prevent exercised-induced reactions.

The point of using omalizumab in the one trial was to see if it helped children ramp up immunotherapy more quickly and tolerate higher final peanut doses. It did, and the nine omalizumab children were on the highest maintenance doses of peanut at 2-year follow-up, with almost all of them consuming an average of at least one peanut a day. Perhaps because of that, three of the four anaphylactic reactions were in the omalizumab group.

The fourth reaction was in a child who completed the OIT trial. There was no anaphylaxis in EPIT children. About 60% in both groups reported eating an average of at least a peanut a day at 1-year follow-up.

About three-quarters of the children ate peanut-containing candy to get their maintenance dose. Others ate peanuts or peanut butter or sprinkled peanut flour on their food. Just six children, all from the EPIT cohort, said they liked the taste of peanuts.

Meanwhile, 6 of the 33 children (18%) – 1 in the omalizumab group, 3 in the EPIT arm, and 2 in the OIT group – refused to eat peanuts after their immunotherapy trials.

Posttrial peanut dosing ranged from once a month to daily, and the majority of subjects ate peanut about five times per week. All of the anaphylaxis children recovered without incident and resumed peanut maintenance. A couple of the children in the EPIT group had an itch in their throat when they switched to eating peanuts, but it resolved on its own. One child in the omalizumab group and one in the OIT group reported gastrointestinal symptoms with maintenance dosing.

The original trials funded the follow-up. Ms. Ott Lewis had no relevant financial disclosures.