Any time people with severe allergies to foods such as peanuts, milk or eggs sit down for a meal—whether at home, a friend’s place or a restaurant—they must pay careful attention to each ingredient they’re eating. Two children in every U.S. classroom and nearly 11 percent of adults have a food allergy and thus must be constantly vigilant. For some, even a trace of the allergen on a fork or spoon could trigger a life-threatening reaction.
Now the drug omalizumab, developed by the company Genentech as an asthma treatment and sold under the name Xolair, has been approved by the U.S. Food and Drug Administration as an injectable treatment for certain food allergies. The study that led to approval was published this week in the New England Journal of Medicine. It showed that the monoclonal antibody treatment quelled allergic reactions in around two thirds of people with allergies to foods that included peanuts, milk and eggs. The results suggest Xolair won’t completely rid people of their allergies—or make it safe for them to eat those foods in large quantities—but it could provide an important safety net in case of accidental consumption or exposure.
“This drug will reduce the anxiety our patients have around doing everyday things that people without food allergies take for granted,” says Sharon Chinthrajah, an allergist and immunologist at Stanford University and senior author of the study.
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Food allergies develop when the body wrongfully identifies food proteins as a threat. Many such allergies involve a type of antibody (a protein that allows the immune system to find and neutralize invaders) called immunoglobulin E, or IgE. When the immune system detects a food allergen, it produces IgE, which binds to protective immune cells in the blood. IgE then seeks out and grabs hold of the food protein, triggering the still attached immune cells to flood the body with inflammation-causing histamines and other chemicals. These chemicals prompt allergic symptoms such as hives, swelling of the lips and anaphylaxis—a dangerous whole-body reaction that causes low blood pressure and difficulty breathing. Xolair effectively dulls IgE’s ability to initiate the inflammatory response; it does this by blocking the antibody from binding to the immune cells.
In the new study, researchers used a randomized controlled trial to test the drug’s efficacy on 177 children and adolescents at 10 medical centers across the U.S. All participants were allergic to peanuts and two other foods, such as cashews, walnuts, hazelnuts, eggs, milk or wheat.
Two thirds of the participants received a Xolair injection every two to four weeks during the trial, depending on their weight and IgE levels, while the remaining individuals received a placebo. After four to five months of treatment—and under close medical supervision—each participant ate a small amount of peanut protein, equivalent to about four peanuts. Two thirds of the participants who had received the drug showed no symptoms of an allergic reaction, but 93 percent of those who took the placebo did. Similar results emerged for most of the other foods tested, though Xolair appeared to protect only 41 percent of people with a cashew allergy. Chinthrajah doesn’t know why cashews might be different. She notes, however, that participants with this allergy did report improvements the longer they were on the drug.
Because Xolair blocks all forms of IgE, whether specific to proteins in nuts, milk or eggs, the researchers also wanted to test whether the drug could prevent allergic reactions to multiple foods simultaneously. The scientists had children eat small amounts of two or three foods they were allergic to at the same time and found that at the four-peanut-equivalent dose, most could tolerate two of the foods, and nearly half could consume three without a reaction. “This is nicely shown in the trial,” says Maria Curotto De Lafaille, an immunologist at the Icahn School of Medicine at Mount Sinai, who wasn’t involved in the research. She notes that this test was important, given that children with one food allergy have a higher risk of developing more.
The drug also worked for children of different ages, including those as young as one year. “So no matter what age you’re diagnosed or what age you’re seeking treatment, this has a good probability of being effective,” Chinthrajah says.
Chinthrajah emphasizes that people using Xolair can still experience allergic reactions; the drug only helped raise the threshold for how much allergen the study participants could tolerate. When the researchers bumped up the test doses, more children showed signs of a reaction. “Our patients still need to be very careful,” she says. The treatment regimen may also be a considerable barrier to some children and adults because a shot is needed every two to four weeks and must be administered by a health-care worker. The doctors who ran the study plan to offer a self-injection option that can be administered at home, similar to the Xolair asthma treatment. But for some children, particularly those with needle phobias, this might not be appropriate.
The drug’s price, around $1,500 per injection, could also deter families without comprehensive insurance. Many insurance companies cover Xolair as an asthma treatment, and Chinthrajah hopes this will hold once doctors start prescribing it for food allergies.
Only one other immunotherapy, called Palforzia, is currently FDA-approved for peanut allergies in children between four and 17 years old. Palforzia is a tiny, repeated dose of peanut protein that is taken orally. Over time this gradually shifts the immune system away from recognizing the protein as a threat and producing IgE. As with Xolair, people who use Palforzia for their peanut allergy still need to avoid peanuts. Lafaille notes that “one of the problems with oral immunotherapy is that there are a lot of reactions, even anaphylaxis,” in response to the treatment itself. By comparison, children who took Xolair and those who took the placebo experienced a similar number of adverse reactions. (Xolair does have a 0.2 percent rate of anaphylaxis, and the medication comes with a boxed warning.) Other promising allergy drugs block interleukins, which are immune chemicals that stimulate the production of IgE in response to an allergenic food. But so far none have been FDA-approved for food allergies.
The clinical trial of Xolair for food allergies is still underway, and the results reported so far have “opened up the door to so many more questions,” Chinthrajah says. In the next stages of testing, the researchers want to combine the drug with Palforzia to see if doing so will offer greater protection. They also want to test children’s tolerance to allergenic foods after stopping Xolair to check whether the drug has long-lasting impacts on the immune system.
Such future research could guide scientists in tailoring Xolair allergy therapy for individual people. Chinthrajah says the drug, as currently approved, can already provide substantial benefits—especially for allergies so severe that a tiny, accidental exposure can be life-threatening. “Hopefully,” she says, they can “live life a little freer.”