Previously, there has been limited research into food desensitisation for people with multiple food allergies due to safety concerns, meaning that this is the first phase 2 randomised trial of its kind. Further research will be needed to confirm the findings before the treatment becomes available.
Around 30% of people with food allergies are allergic to multiple foods, putting them at higher risk of accidental exposure and anaphylaxis, which can be fatal. People with multiple food allergies can have allergies to similar foods (such as different tree nuts, like walnut, almond, hazelnut, cashew, pistachio and Brazil nuts) or to a range of foods. There is currently no treatment for people with food allergies.
The authors say that the omalizumab may work by moderating the immune system’s response to trigger foods, allowing people with allergies to begin food desensitisation. This involves introducing small amounts of the trigger food (in flour form mixed into another food) into a person’s diet, then gradually building up the amount with the aim of helping their immune system to tolerate the food.
“This phase 2 clinical trial shows the potential benefits of using omalizumab to facilitate food desensitisation to multiple trigger foods in a shortened period of time,” says Dr Sharon Chinthrajah, Director of the Clinical Translational Research Unit of the Sean N Parker Center for Allergy and Asthma Research at Stanford University, USA. “While our results are promising, they are preliminary and suggest that children with multiple food allergies might one day be safely desensitised to their trigger foods using this treatment combination.”
In the trial, 48 children aged 4-15 years old with two or more food allergies were given injections of either omalizumab or placebo for 16 weeks (36 children had omalizumab, 12 had placebo). Eight weeks into their injections, they began food desensitisation for two to five trigger foods until week 36 of the trial.
The food desensitisation was tailored to each participants’ allergies and included equal proportions of each food protein for their trigger foods. This dose increased up to 2 g of protein for each trigger food.
The children had a food challenge which involved eating 2 g protein of each of their trigger foods 36 weeks into the trial.
The researchers found that more children in the omalizumab group than the placebo group were able to eat the protein for at least two foods without an allergic reaction (83% [30/36 children] vs 33% [4/12 children]).
These effects were also seen when testing the children for more than two foods. Among children who had more than two food allergies, more of those in the omalizumab group showed tolerance for their other trigger foods allergens. For example, in the omalizumab group, 81% (21/26) of children with allergies to three or more foods passed the food test for at least three foods, compared to 29% (2/7) children in the placebo group, and 76% (13/17) children with four allergies who had omalizumab passed the food test, while none of the five children in the placebo group did.
On average, the children who had omalizumab tolerated higher levels of trigger food protein in the first week of food desensitisation, compared to children given placebo (250 mg vs 11 mg per food), and were able to tolerate the highest dose of their trigger food protein (2 g) sooner (in 12 weeks, compared to 20 weeks).
The children who had allergies to similar foods also showed that desensitisation to one food type had effects on the related food allergy – with 83% (20/24) of children treated for cashew allergies passing a food test for pistachio, and all children (17/17) who were treated for a walnut allergy passing a pecan nut food challenge. The authors note that further research will be needed to understand this potential effect.
The children involved were closely monitored throughout the trial. While there were no serious adverse events in the study, during the food desensitisation all children experienced at least one adverse event, which were typically gastrointestinal symptoms.
The authors note some limitations, including that children who failed food desensitisation started open label omalizumab with food desensitisation afterwards, which may affect the results relating to adverse events in the study. It is still unclear how omalizumab works to treat food allergies, as the study included only limited assessments of the effects of the drug on the immune system. More studies are needed for a full understanding of how biological medications could improve food immunotherapy.
The researchers are still researching the drug to see if extending the course of treatment improves the effects.
Writing in a linked Comment, Professor Lars K Poulsen, Copenhagen University Hospital at Gentofte, Denmark, says: “The current food allergy epidemic appears to be a perfect storm involving an increased prevalence of sensitised children, an increased severity profile, and a broadening of reactivity from fewer to more allergenic foods… By including participants with a high level of sensitisation… the study addresses the most severely affected and thus difficult-to-treat part of the food allergic population.”
Source: The Lancet Gastroenterology & Hepatology