A new study from the University of British Columbia suggests a safe approach to conquering food allergies for older children and anyone who cannot risk taking allergens orally in order to build up resistance. Sublingual immunotherapy (SLIT) involves inserting small quantities of food allergens under the tongue.
A study conducted by UBC clinical professor and pediatric allergist Dr. Edmond Chan and his team at BC Children’s Hospital Research Institute discovered that SLIT is equally safe and effective for high-risk older children and adolescents as oral immunotherapy is for preschoolers.
“Our work confirms the safety and effectiveness of SLIT for older children and adolescents with multiple food allergies at higher risk of severe reaction,” said Dr. Chan. “These are patients for whom oral immunotherapy would typically be denied because it’s felt to be too risky, so this could be the best approach for that population.”
Our work confirms the safety and effectiveness of SLIT for older children and adolescents with multiple food allergies at higher risk of severe reaction. These are patients for whom oral immunotherapy would typically be denied because it’s felt to be too risky, so this could be the best approach for that population.
Dr. Edmond Chan
Previously published studies from Dr. Chan’s team demonstrated that preschool oral immunotherapy is both safe and effective in the real world. The treatment includes a “build-up phase” of many months in which patients visit a clinic every two weeks to consume a greater dose of an allergen under medical supervision before returning to the same daily dose between visits. When they achieve a particular amount, which is usually around 300 mg of protein, they start a “maintenance phase” in which they take their goal daily dose at home. After a year of maintenance dosages, about four out of every five patients can pass an oral challenge test in which they tolerate a substantially greater amount of 4,000 mg protein.
However, the build-up phase is risky for older children and those with a history of severe reactions. Dr. Chan’s group has been looking for a safer way to get this at-risk group of patients to the maintenance phase.
They recruited about 180 such patients between the ages of four and 18, most with multiple food allergies. The SLIT protocol (started when COVID-19 pandemic restrictions were in place) required patients to have virtually supervised appointments 3-5 times over several months to build up to a small dose – in most cases, just 2 mg of protein – which is absorbed through the membranes under the tongue rather than swallowed and ingested.
The patients’ caregivers learned how to mix and administer these doses at home using novel recipes based on products you can buy at the grocery store, developed with the team’s research dietitian. A wide variety of allergens were treated, including peanut, other legumes, tree nuts, sesame, other seeds, egg, cow’s milk, fish, wheat, shrimp, and other allergens. Patients took these doses daily for 1-2 years.
“It takes up to twice as long as oral immunotherapy, but we wouldn’t have had it any other way, because we needed the superior safety of SLIT for these older kids that are felt to be more severe,” said Dr. Chan.
While most patients had mild symptoms during the build-up phase, none had severe reactions during either build-up or maintenance. Seventy per cent of those tested at the end of the protocol could tolerate 300 mg of their allergen — a success rate nearly as high as that for oral immunotherapy.
The results were encouraging for a therapy that any family can undertake at home with guidance from professionals.
“Aside from safety concerns in older children, allergists are frequently overwhelmed by the oral immunotherapy build-up phase, which can take 11 or more clinic visits. “They just don’t believe they have the capacity to provide that many visits in their office,” Dr. Chan explained. “In our clinic, we are beginning to adopt more home-based approaches because the demand for medical sessions that require supervision far outstrips the availability. We are working to establish a data-driven method that matches a patient’s risk level with the appropriate level of supervision. Our SLIT research indicates that home-based SLIT buildup is safe.”
Ultimately, the trial highlights an alternative that allergists should now consider for patients who cannot safely undertake oral immunotherapy. The trade-off for greater safety is simply a longer timeline, but it comes with the benefit of keeping clinics free for those who need them most.
