ATLANTA -- Children and teens who participated in three separate peanut immunotherapy studies showed a high rate of anaphylaxis requiring epinephrine if they kept with the peanut challenge at home, researchers reported here. Four of 27 participants (14.8%) who continued the peanut desensitization after leaving the studies had allergic reactions, including three patients enrolled in a trial of oral immunotherapy plus omalizumab (Xolair) and one patient enrolled in trial of oral immunotherapy alone, reported Megan Ott Lewis, MSN, RN, of the Children's Hospital of Philadelphia (CHOP), and colleagues.
The analysis included 33 children and teens. Surveys were completed by study participants or their parents roughly 2 years (oral therapy plus biologic) or 1 year (oral therapy alone and EPIT) after the trials ended. All 33 reported satisfaction with having participated in the immunotherapy studies, but 17 reported that dosing during the clinical trial interfered with daily life. Post-trial peanut consumption frequency varied from monthly to daily, with most surveyed participants consuming peanut about five times a week. All participants were told to maintain 2-hour exercise restrictions after dosing, and 22 reported following this recommendation.
Among the patients introducing peanuts into their diets following the study, 74% ate peanut-containing candy, 15% ate peanut flour mixed in foods, and 11% ate peanuts. Doses were determined based on individual and study team preference. Participants in the oral immunotherapy plus omalizumab study consumed the highest post-trial dosages of peanut, with 100% achieving an average daily dosage of 300 mg or more compared with 66% of the oral immunotherapy alone group, and 75% in the EPIT group. Ott Lewis told MedPage Today that this higher post-study dosage could explain the higher peanut-induced anaphylaxis incidence in these patients. Physical exertion, which increases the risk for allergic reactions following food challenge, was not a factor in any of the episodes, she said.
"Higher maintenance doses seem to be associated with this reaction," she said, adding that most kids and teens with peanut allergies don't really like peanut-containing foods. Only six survey participants reported liking the taste of peanuts or foods containing peanut, which did not surprise co-author Jonathan Spergel, MD, PhD, also of CHOP. "The body is pretty smart. Most kids with peanut allergies have no interest in eating peanut butter sandwiches all day," he told MedPage Today.
Spergel called the four allergic reactions among the 27 participants who continued peanut ingestion "concerning," adding that the optimal dosage of peanut consumption following oral or epicutaneous immunotherapy remains to be determined. It also remains to be seen if continued ingestion will lead to permanent desensitization. "My guess is that we will see something similar to what we have seen with the rest of allergy immunotherapy," Spergel said. "Allergy shots are typically given for 3 to 5 years." But Spergel cautioned that 3 - 5 years of ingestion following peanut immunotherapy may or may not lead to permanent desensitization. "We just don't know yet," he said.
Dr. Katherine Bloom of Allergy & Asthma Care of Fairfield County comments: "Oral immunotherapy to foods remains an experimental treatment, and we need to learn much more about this approach to food allergy before it should be offered to the general population. With a risk of anaphylaxis seen here of 4 in 27 patients, a higher incidence of anaphylaxis than many peanut allergic patients not in treatment, oral immunotherapy may be most appropriate in patients with a history of frequent reactions or extreme sensitivity to small amounts of peanut protein. We look forward to more studies regarding this and the peanut patch, and hope to have a form of FDA approved food immunotherapy available within the next few years."