Sublingual Immunotherapy Reduces Peanut Allergy

CHAPEL HILL, N.C.For the more than 3 million Americans who have allergies to peanuts, tree nuts or both, complications from ingesting or even just touching the nuts can cause life-threatening allergic reactions, such as anaphylaxis. In the past, patients had to adhere to  strict dietary elimination of peanuts; however, a new study published in the Journal of Allergy and Clinical Immunology shows promise for sublingual immunotherapy (SLIT).

Developed at the University of North Carolina School of Medicine, SLIT is a treatment in which patients are given daily doses, in gradually increasing amounts, of a liquid containing peanut powder. The patients first hold the liquid under the tongue for 2 minutes and then swallow it.

For the study, 40 people with peanut allergy, ages 12 to 37 years, were randomized to receive daily peanut or placebo SLIT. All were given a baseline oral food challenge of up to 2 grams of peanut powder to test how much peanut powder they could consume without symptoms. After 44 weeks, all were given a second oral food challenge. Those who were able to consume either 5 grams, or at least tenfold more peanut powder than their baseline amount, were considered to be responders (i.e., desensitized to peanut). At 44 weeks, 70% of those who received peanut SLIT were responders, compared to 15% of those receiving placebo. Among the peanut-SLIT responders, the median amount of peanut powder they could successfully consume increased from 3.5 to 496 milligrams. After 68 weeks, that amount increased significantly, to 996 milligrams. Of 10,855 peanut doses given through week 44 of the study, 63.1% were symptom-free. When oral/pharyngeal symptoms were excluded from the analysis, 95.2% of doses were symptom-free.

These results are encouraging," the researchers said. The immune response was stronger than we thought it might be, and the side effects of this treatment were relatively small. However, the magnitude of the therapeutic effect was somewhat less than we had anticipated. That's an issue we plan to address in future studies."

The study concluded that peanut SLIT safely induced desensitization in a majority of participants compared to placebo, and that longer duration of therapy led to significant increases in the amount of peanut powder people could safely consume.