Oral immunotherapy curbs peanut allergy
DEAR DOCTOR: My 5-year-old nephew has a severe peanut allergy. I’ve read about a new peanut allergy drug that is an oral immunotherapy. How does it work?
DEAR READER: We are parents as well as physicians, so we understand the nonstop vigilance that comes with a food allergy. But peanuts are common enough that, despite a family’s best efforts, it’s likely a child with a peanut allergy will come into contact with them at some point. That’s why the potential of the new immunotherapy drug you mentioned is so exciting. Not only does it offer people with peanut allergies a new measure of protection, it opens up a range of possibilities for future allergy therapies.
The new drug, currently known as AR101, is under review by the Food and Drug Administration. This follows the completion of a series of clinical trials in the efficacy and safety of the drug. AR101 works by very gradually exposing an individual to peanut proteins, which desensitizes the immune system. This takes place over the course of six months, during which the peanut content in the daily oral dose is methodically increased. At the end of a year — six months of treatment followed by six months of maintenance — 67 percent of the children in the study were able to safely eat two peanuts. Researchers have made it clear that the goal is not to cure the allergy, but to reduce the severity of symptoms should accidental exposure to peanuts ever take place.
Unfortunately, the drug didn’t work for everyone. More than 10 percent of the participants exited the study
before it was complete due to adverse reactions. Of those who remained, 14 percent required intervention with epinephrine, which eases symptoms. The bad news for adults living with a peanut allergy is that the treatment was not effective in those adults who were enrolled in the clinical trials.
For those who aren’t aware, peanut allergy is one of the most common causes of severe allergy attacks in children. A reaction can be triggered by even a tiny amount of the legume, and symptoms range from mild to severe. They include runny nose, itching or tingling in the mouth and throat, hives or other skin reactions, gastric distress like nausea, vomiting or diarrhea, and respiratory issues like wheezing, shortness of breath or a tightening of the throat. At its most severe, a peanut allergy can cause anaphylaxis, a life-threatening reaction that is causing an increasing number of hospitalizations. Symptoms include swollen airways that prevent breathing, a precipitous drop in blood pressure and loss of consciousness.
A challenge of the treatment is that after receiving each daily dose of the medication, children have to rest for two hours but cannot sleep during that time. Still, physicians and researchers are buoyed by the results. AR101 has been flagged by the FDA as a breakthrough therapy, which makes it eligible for a swift approval process. If all goes well, the manufacturer reports that the drug could be available by the end of 2019.
Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.