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• Posted February 10, 2023

Mouse Study Hints at New Treatment for Peanut Allergy

People with peanut allergies have to be vigilant about avoiding the food and always be armed with emergency treatment. Now scientists say they've taken an early step toward a drug that could prevent severe reactions to peanuts in the first place.

The compound has only been tested in lab mice, and no such drug will be available for people anytime soon, experts stressed.

But in early experiments, researchers found that the drug protected lab mice from severe allergic reactions to peanuts for more than two weeks. However, animal findings do not always pan out in humans.

The vision is to have a self-injected medication that people with peanut allergy can take every couple weeks, or maybe once a month, according to researcher Mark Kaplan, chair of the Department of Microbiology and Immunology at Indiana University School of Medicine.

It would not be a "cure" for the condition. But it could give people an additional layer of protection should they accidentally ingest peanuts.

"Accidental exposure is always a real risk," Kaplan explained.

That's because peanuts are harder to avoid than many people realize, he noted.

They are often used as ingredients in processed or prepared foods, and cross-contamination is also possible -- when the same equipment that has touched peanuts is used for other foods, too. Even though parents and adults with peanut allergy studiously read labels and take other precautions, accidents happen.

So people with peanut allergy have to carry an auto-injector of epinephrine in the event they suffer a reaction. That can include anaphylaxis, a life-threatening allergic reaction where people may struggle to breathe, have a drop in blood pressure or lose consciousness.

An estimated 2% of U.S. children are allergic to peanuts, and for most the allergy continues into adulthood. That makes it the most common food allergy among kids, and the third-most common among adults, according to the nonprofit Food Allergy Research and Education (FARE).

When people have peanut allergy, immune system sentries called IgE antibodies see peanut protein as a threat. When those antibodies detect the protein, they trigger the release of inflammatory chemicals, such as histamine, that cause the allergic reaction.

The new study, published Feb. 8 in the journal Science Translational Medicine, involved a compound dubbed cHBI. It essentially inhibits IgE antibodies' ability to recognize the peanut protein, allowing it to travel through the body without alerting the immune response to any real threats.

Kaplan and his colleagues tested the inhibitor in lab mice that had been outfitted with human immune cells, including ones derived from people with peanut allergy. They found that a single dose of cHBI prevented the animals from having an allergic reaction to peanut protein for over two weeks.

Bruce Roberts is chief research strategy and innovation officer at FARE. He said the findings are interesting, and "shine a bright light on the need for new treatments for peanut allergy."

But Roberts, who was not involved in the study, also questioned the real-world usefulness of such an approach: People would have to regularly inject themselves with a medication -- that's unlikely to be cheap -- to prevent an allergic reaction that might or might not happen.

"I think that would be a tough sell to parents and to patients with peanut allergy," Roberts said.

He also pointed to an existing option: oral "immunotherapy," which educates the immune system to tolerate peanuts.

There is one such therapy, called Palforzia, approved by the U.S. Food and Drug Administration for treating peanut allergy. It's a peanut flour product that patients take by mouth -- mixed into applesauce, for instance -- in a standardized schedule: They start with tiny amounts that are gradually increased, until the immune system is "desensitized" to peanut protein.

Unlike that approach, Roberts said, the experimental drug would not provide any immune system education.

That's not to say Palforzia is a panacea, both experts said. It does not work for everyone, can have side effects like vomiting and nausea, and has its own real-world issues: The drug was approved in 2020, but not many doctors and patients seem to be using it.

New, additional options are definitely needed, according to Roberts.

He said he thinks the future may be in "allergen-agnostic" approaches that are under study. That means therapies that target areas of the immune response that are common to all food allergies.

Many people, Roberts noted, are allergic to more than one food. Of children with allergies to tree nuts -- like almonds, walnuts and cashews -- about 40% are also allergic to peanuts, according to FARE.

As for cHBI, Roberts said time, and further research, will tell.

"Maybe this could be one answer," he said. "But it's too early to say."

More information

FARE has an overview of common food allergies.

SOURCES: Mark Kaplan, PhD, chair, Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis; Bruce Roberts, PhD, chief research strategy and innovation officer, FARE, McLean, Va.; Science Translational Medicine, Feb. 8, 2023, online