Gradual exposure to peanut protein powder over six months helped more than half of kids with peanut allergies learn to tolerate the equivalent of about 10 peanuts per day, according to the results of a new clinical trial.
The Phase 2 trial also found that the overwhelming majority of kids who tested the experimental therapy were able to eat the equivalent of about five peanuts each day without having an allergic reaction. This led to significant improvements in the quality of life for the families of these children, according to a report published Thursday by the Lancet.
Experts estimate that 15 million Americans and another 17 million Europeans are allergic to peanuts, and most of them are children. Among food allergies, reactions to peanuts are the "most common cause of severe and fatal allergic reactions," the study authors wrote. As many as half of all kids with peanut allergies wind up eating them by accident over the course of a year, and the constant fear of eating hidden peanuts is a big drag on the quality of life for these kids and their families.
A group of researchers from the U.K. has been experimenting with oral immunotherapy as a way to desensitize kids to peanuts. Their regimen involves feeding kids increasingly higher doses of a finely ground peanut protein powder, mixed in with their regular food. It starts with a dose of 2 milligrams of peanut protein powder per day, then building to a daily dose of 5 mg, 12.5 mg, 50 mg, 100 mg, 200 mg, 400 mg and finally leveling off at 800 mg. (Oral immunotherapy, or OIT, has been tested for allergies to eggs and milk as well.) In the peanut study, the first exposures to each dose occurred at a clinical research facility; after that, kids were able to eat at home.
The trial, known as STOP II, involved kids between the ages of 7 and 16. After six months, 24 of the 39 kids who tried OIT were able to tolerate 1,400 milligrams of peanut protein each day, for a success rate of 62%, the researchers found. Those 1,400 mg are the equivalent of eating about 10 peanuts – more than someone with allergies is likely to eat by accident.
In addition, 84% of the kids were able to tolerate a daily dose of 800 mg of peanut protein at the end of the six-month period. That's roughly the amount of protein found in about five regular peanuts, according to the study. The average amount of peanut protein that kids could tolerate without having an allergic reaction was 25.5 times greater than it was before they began the sensitization protocol.
Meanwhile, none of the 46 kids in the control group were able to tolerate either level of peanut exposure after following their usual routine of simply avoiding peanuts as much as possible. Making matters worse, the average amount of peanut protein that they could tolerate fell slightly over the six-month period, according to the study.
In the second phase of the trial, the kids in the control group were invited to try OIT. Six months later, 54% of them were able to handle 1,400 mg of peanut protein powder each day, and 91% could tolerate a daily dose of the 800 mg, the researchers reported.
Most of the side effects of the therapy were mild, and they included itchy mouth, abdominal pain, nausea and vomiting, according to the study. A total of 22% of study participants experienced wheezing, though that occurred after only 0.41% of the doses administered. One study volunteer had to use a device like an EpiPen. No one was admitted to a hospital as a result of peanut exposure.
Quality of life improved for kids in both groups as they stopped having to worry so much about the negative consequences of accidental exposure to peanuts, the study authors reported.
"The families involved in this study say that it has changed their lives dramatically," study leader Dr. Andrew Clark, of Cambridge University Hospitals, said in a statement.
To maintain the benefits seen in this study, kids would have to keep eating peanut protein powder for as long as several years, the study authors noted. In past studies, subjects who stopped OIT after nine months saw their allergies return.
The results from STOP II are "exceptionally promising," Dr. Matthew Greenhawt, research director of the University of Michigan Food Allergy Center, wrote in a commentary that accompanied the Lancet study. However, he cautioned that OIT as a treatment for peanut allergies "remains experimental." More studies are needed – especially ones involving larger groups of patients, younger children, and kids with severe reactions to peanuts – to to determine whether OIT is safe and cost-effective, he wrote.
The therapy "is years away from routine clinical use," Greenhawt wrote. The additional research needed "must be done without added pressure or heightened expectations to quickly produce a marketable therapy."
The study authors echoed his concerns, warning patients and their families not to try OIT on their own. "Because of the significant risks involved, OIT should be restricted to specialist centers," they wrote.