Peanut allergy is a serious and sometimes life-threatening allergy. Presently, it is estimated that 1% of the population has a food allergy to peanut. Building tolerance to peanut allergy through Oral Immunotherapy (OIT) has been studied for years and is ongoing. Oral immunotherapy is a promising investigational therapy aimed at producing allergy desensitization through graduated exposure to an allergen dose.
In research studies, exposure to peanut allergen is done under medical supervision and generally involves eating a peanut protein powder that is mixed in food. During periodic doctor visits, the peanut dose is gradually increased to a pre-determined maintenance level. After each dose increase at the doctor’s office, the patient returns home and continues the dose for a time period, returning to the doctor’s office for dose increases.
The use of OIT for peanut allergy produces a temporary tolerance using ongoing and controlled exposure to the peanut allergen. Tolerance to peanut wanes if ongoing exposure is withdrawn.
While research in this area is exciting and promising, experts warn that setbacks may occur with individual patients. For example, about 20% of those studied with OIT have failed this course of treatment. Others have had reactions at home while on a maintenance dose. Sometimes there have been reactions to doses previously tolerated, occurring most frequently during illness, menstruation and exercise. Still others who may have missed their daily dose may lose the effect of OIT and have a subsequent reaction when exposed to the allergen.
However, some studies have shown glimmers of promise for lengthy peanut desensitization, such as the 2013 study published in the Journal of Allergy & Clinical Immunology, which showed that 50% of study participants demonstrated desensitization after 5 years of treatment.
All in all, OIT is not yet an approved treatment for food allergic individuals, however it is being actively studied. Many experts believe that larger studies are needed before FDA approval.
Recently, a study published in The Lancet showcased the latest results in an ongoing effort to study OIT for peanut allergy. Researchers from the UK attempted to desensitize 99 peanut allergic children, aged seven to sixteen years, using peanut powder that was mixed with food. All study participants had some level of peanut allergy, defined by an immediate reaction after eating peanut, including a positive skin-prick test and positive for a double-blind food challenge. The goal of the study, called STOP II, was to establish peanut desensitization, defined as a negative peanut challenge to 1400 mg peanut powder at 6 months.
Initially, the children were divided into two groups: the “active group” which received 800 grams peanut powder (equivalent to 5 peanuts) daily, and the “control” group which avoided all peanut.
The active group was initially offered small amounts of peanut powder and gradually advanced to 800 grams of peanut powder (equivalent to 5 peanuts), provided on a daily basis.
After this first phase of the study, sixty-two percent of the “active group” participants were able to tolerate this small dose of peanut without allergic reaction—they were desensitized to peanut. The members of the control group were not. The “control group” was then included and offered 800 grams of peanut powder, similar to the active group.
Eighty-four percent of both the active and control groups tolerated the peanut dose of 800 grams, and their immunologic parameters supported this, showing increased threshold dose (the point at which exposure causes a reaction) to peanut.
The second phase of the study involved eating higher amounts of peanut powder (1400 grams powder, equivalent to 10 peanuts). Fifty four percent of the participants were able to tolerate this dose, while ninety-one percent of the children tolerated the 800 gram peanut dose.
The most common side effects among study participants were gastro-intestinal events, including nausea, vomiting and diarrhea. Several participants experienced oral pruritis and wheezing. One participant required Epipen injection.
This study shows the continued potential promise of desensitization using OIT for peanut allergic individuals. However, further studies need to be completed with larger groups of individuals of varying ages. Many questions remain, such as how long does desensitization last? Can this lead to a cure from peanut allergy? What happens to a food allergy with long-term OIT use? What is the most effective dose?
The one participant who did require emergency treatment underscores the need for close medical supervision and a controlled environment. Be careful if you seek this treatment from a physician, as it is not approved for clinical use to date. And most definitely, do not attempt to do this at home.
Sicherer, S. Food Allergies: A Complete Guide for Eating When Your Life Depends on It. 2013. The Johns Hopkins University Press
FARE: Food Allergy Research & Education www.foodallergy.org
Anagnostou K, Islam S, King Y, Foley L, Pasea L, Bond S, Palmer C, Deighton J, Ewan P, and Clark A. Assessing the efficacy of oral immunotherapy for the desensitization of peanut allergy in children (STOP II): a phase 2 randomized controlled trial. The Lancet. January, 2014. doi:10.1016/S0140-6736(13)62301-6
Vickery BP et al. Sustained unresponsiveness to peanut in subjects who have completed peanut oral immunotherapy. J Allergy Clin Immunol. 2013 Dec 19. pii: S0091-6749(13)01750-8. doi: 10.1016/j.jaci.2013.11.007
National Institute of Allergy and Infectious Diseases. 2011. Parent's Guidelines for the Diagnosis and Management of Food Allergy in the United States.