CATEGORY: IMMUNE HEALTH
In children allergic to peanut and at least two other foods, four months of injections of omalizumab—an antibody drug used for two decades against severe asthma—let 67% eat the equivalent of about two and a half peanuts without a serious reaction, compared with 7% of children given placebo injections, according to a randomized trial published in the New England Journal of Medicine.1 The same children also became far less reactive to cashew, milk and egg. The result led the U.S. Food and Drug Administration to approve the drug for food allergy in February 2024, the first medicine ever cleared to reduce reactions across many foods at once.
Three Allergies Each, a Coin Flip, and Measured Mouthfuls of Peanut
The trial, called OUtMATCH, screened 462 people and enrolled 180 with a confirmed peanut allergy plus allergies to at least two of cashew, milk, egg, walnut, hazelnut or wheat—177 of them children and teenagers aged 1 to 17 (median age 7) and three adults. Each was assigned by chance, two to one, to omalizumab or to matching placebo injections given under the skin every two to four weeks for 16 to 20 weeks, with the dose set by body weight and by the level of IgE—the allergy antibody—in the blood. Because chance rather than choice decided who got the drug, the two groups started out alike, and any difference at the end belongs to the drug. Before treatment and again at the end, every participant went through an oral food challenge: eating slowly increasing, carefully weighed amounts of each food under medical supervision until a reaction appeared or the top dose was reached. The primary question was how many could take in at least 600 mg of peanut protein—roughly two and a half peanuts—with no more than mild symptoms. The trial was funded by the National Institutes of Health, with the drug and additional support supplied by its makers.
Why Soaking Up One Antibody Calms Reactions to Many Foods
A food allergy is a case of mistaken identity. The immune system has made IgE antibodies shaped to fit peanut, milk or egg protein, and those antibodies sit on the surface of mast cells—cells packed with histamine and other chemicals—like tripwires. When the food arrives, the wires are pulled and the cells dump their contents, producing hives, swelling, vomiting or, in the worst cases, a dangerous drop in blood pressure. Omalizumab does not care which food an IgE antibody is built for; it binds free IgE in the blood before it can settle onto mast cells, so fewer tripwires are laid. That is why one drug can raise the threshold for several unrelated foods at once, something no food-specific treatment can do.
Seventy-Nine Children Out of 118, Versus Four Out of 59
After four months, 79 of the 118 participants on omalizumab (67%) passed the 600 mg peanut challenge, against 4 of 59 (7%) on placebo. The pattern repeated food by food at a 1,000 mg threshold: cashew 41% versus 3%, milk 66% versus 10%, and egg 68% versus 0%. The first 60 participants to finish then continued omalizumab openly for another 24 weeks; at that point 67% could eat a cumulative 1,044 mg of peanut protein and 44% could eat 6,044 mg—about 25 peanuts—without a serious reaction. Side effects were similar between the groups apart from more injection-site reactions on omalizumab. One serious adverse event occurred, a rise in liver enzymes in a one-year-old, which the investigators judged unlikely to be caused by the drug.
Protection From an Accident, Not Permission to Eat Freely
The trial did not test whether treated children could add peanut or milk back into their diets, and the investigators were explicit about what the result means. Lead investigator Robert Wood called the findings potentially life-changing while noting that patients “will still need to avoid the foods” and continue to carry self-injectable epinephrine. The threshold gain is a margin of safety against the accidental exposures—the mislabeled cookie, the shared utensil—that account for most emergency reactions. Whether any protection lasts once the injections stop was not tested; the drug mops up IgE rather than retraining the immune system, and in the trial it was given every two to four weeks throughout. A third of the children on omalizumab did not reach the 600 mg peanut mark, so the drug does not work for everyone.
A Smaller Danish Trial Pointed the Same Way
The finding has independent company. A Danish randomized trial published the same month gave omalizumab or placebo to 20 children aged 6 to 17 with severe food allergy and found that the treated children could tolerate substantially larger amounts of the food protein than those on placebo at three and six months.2 That trial is far too small to carry a conclusion on its own, but it lands in the same direction as OUtMATCH and was run by a separate group in a different country, which is the kind of replication that makes a result worth trusting.
Key Takeaways
- Four months of omalizumab injections let 67% of children with multiple food allergies eat about two and a half peanuts’ worth of peanut protein without a serious reaction, versus 7% on placebo—79 of 118 children against 4 of 59.
- Reaction thresholds rose for cashew, milk and egg as well, because the drug blocks the allergy antibody itself rather than the response to any one food.
- Participants were assigned by chance, so the difference can be credited to the drug; a smaller Danish trial found the same direction of effect.
- The trial tested protection against accidental exposure, not eating the foods freely; the investigators stressed that avoidance and epinephrine remain part of care, and about a third of treated children did not reach the peanut threshold.
References
- Wood RA, Togias A, Sicherer SH, et al. Omalizumab for the Treatment of Multiple Food Allergies. New England Journal of Medicine. 2024;390(10):889–899. link
- Mortz CG, Parke L, Rasmussen HM, Kjaer HF, Bindslev-Jensen C. A randomized, double-blind placebo-controlled study on the efficacy of Omalizumab on food allergy threshold in children with severe food allergy. Allergy. 2024;79(4):964–976. link