The Hunt for a Food Allergy Cure: Where Is It Heading?
But how better can it be made? Back at the AAAAI meeting, Burks was raising one of the key issues in food allergy therapy. Can you ever find true, lasting tolerance – that elusive cure? In fact, he even described the term ‘tolerance’ as “extremely controversial” to define, preferring to speak of allergic patients attaining “sustained unresponsiveness”.
It helps to understand the terminology. Sicherer notes that “desensitization” simply means that the food-allergic patient, through a therapy, is able to gain some level of protection to an allergenic food, such as peanut. That person has to keep taking an assigned amount of peanut “dose” every day or the protection will diminish or even disappear. “If you stop taking it as a daily treatment, you go back to being perhaps as sensitive as you were before,” he says.
In some studies, patients are taken off their doses for a few weeks and then tested to see if they sustain their threshold of “unresponsiveness”. But that wasn’t the case in the Johns Hopkins follow-up study of the 32 who had undergone milk oral immunotherapy. Umetsu and Nadeau say those findings serve as a reality check, that the long term remains the big question mark.
They note that the study is preliminary [Ed.’s Note: It is now published in JACI, Sept. 2013] and one vital point remains unclear: after the trial, only about half of the patients had stuck to their full daily serving of milk. What happened to the rest?
Dr. Corinne Keet of Johns Hopkins led that follow-up. She says in the case of 16 percent who stopped taking their milk doses outright, they quit because of reactions. When it came to the others who were having varying degrees of reactions, the picture is less clear.
But Wood, the Johns Hopkins director, says: “The main thing I’ve come to believe is that they were not as protected as we believed and that they self-restricted [consumption] because they didn’t like the side effects the milk was putting them through.”
Past OIT studies have shown that factors such as catching a cold, exercise and menstruation can have an impact on the threshold at which an allergic study participant will react. If a person pulls back allergen consumption because of symptoms, he or she needs to gradually work back to the full dosing. It’s not yet known if any of these factors were issues in the Johns Hopkins study.
The big picture discussion raises this intriguing question: in the quest for a food allergy cure, might this be a two-stage process, one in which an allergic patient’s threshold of protection to an allergen is first significantly raised through oral immunotherapy, or OIT plus Xolair – or perhaps via Chinese herbs or another therapy?
That’s desensitization, which offers a safety net against an accidental exposure. The second stage would be the continuing hunt for the cure.
At the AAAAI conference, some researchers felt that first goal was less than adequate, even in the short term. “But that is personal opinion,” says Sicherer. “If you’re the parent of a child, who has had multiple allergic reactions despite your best efforts, you might say, ‘This sounds good to me.’”
Burks also views that as a huge step for the average patient. “If a patient can tolerate the procedure, they’re likely after a year of therapy to tolerate a whole lot more food [allergen] than when they started, and that change stays as long as they’re on the therapy.”
When it comes to the longer term, the moving target of finding a true cure for food allergy, Californian Nadeau can hold out this ray of optimism: in her small studies with the combination of Xolair and oral immunotherapy, patients’ immune systems are actually changing.
“It’s only in a few patients, but we’ve shown that indeed their immune systems became more like those people who have naturally lost their food allergy. We’re not yet able to offer what we think is a cure,” she says. But here’s what she, and the other experts, can offer: “There is a lot of promise and hope.”
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Next: How to join a study
See also: Brave Girl’s New Food Freedom