Photo Credit: Sergeyryzhov

Researchers found that using real food from grocery stores instead of allergen extracts helped expedite sublingual immunotherapy without posing safety risks.

A clinical protocol that used real food instead of allergen extracts was safe and helped expedite the course of sublingual immunotherapy (SLIT), according to a study published in The Journal of Allergy and Clinical Immunology: In Practice

“Commercial food allergen extracts have been repurposed as the food source in SLIT trials. The aim of this study was to make this promising form of food desensitization more readily available to patients by transitioning from extract-based SLIT to a less expensive food source of equal or greater potency while using a briefer, more cost-effective protocol,” Hugh H. Windom, MD, and colleagues wrote.

Real Food Samples

The study involved 50 patients who initiated food SLIT from March 2022 to October 2023 at an allergy center in Florida. Patients included in the study had a history of reactions, food-specific IgE levels greater than 0.5 kU/L, and positive epicutaneous skin testing results with wheal sizes at least 5 mm larger than control.

Just over half (56%) of the patients received single-food SLIT. Among patients undergoing multi-food SLIT, 59% were treated with two foods, 36% with three foods, and 5% with four foods.

SLIT treatments involved a liquid form of real foods including peanut, egg, milk, cashew, walnut, hazelnut, wheat, sesame, and sunflower seed. Only three of these foods were not easily accessible to patients at local grocery stores. Clinicians diluted the foods with 50% glycerin saline for early updose visits, then used liquid forms in full strength at later and ongoing maintenance visits. For peanut, sesame, and wheat SLIT, clinicians prepared the solutions with both flour and glycerin.

Patients initiated SLIT at the clinic, receiving a series of doses spaced out by 20 minutes. Clinicians used syringes instead of droppers to administer the doses, instructing patients to hold the liquid under their tongues for two minutes before swallowing. Patients then went home and continued to administer their last tolerated doses once daily until returning to the clinic for their next updose visits, scheduled at least one week apart.

“The first 20 patients began treatment at a 1:1000 dilution on day 1, and the next 30 patients began at a 1:100 dilution,” Dr. Windom and colleagues wrote.

Safe & Simple Treatment 

The participants underwent daily treatment for a median of 23 weeks (IQR, 14-41). Patients in both the 1:1000 and 1:100 cohorts tolerated SLIT therapy well, with no epinephrine use throughout the study.

One patient in the 1:100 cohort receiving multi-food SLIT reported heartburn after their third visit, which clinicians resolved by temporarily downdosing. Six patients did not reach the maintenance dose due to several factors such as being unable to hold the dose under their tongue for 2 minutes, insurance loss, and new reactions to previously tolerated foods.

For patients in the more concentrated SLIT cohort, the dosing protocol was expedited from a seven-dose buildup to only four dosing visits. Patients in the 1:1000 cohort reached their maintenance dose in a median of 14 weeks (range, 6-58), while patients in the 1:100 cohort reached it in 7 weeks (range, 4-22).

Twelve participants also underwent exercise testing. Patients used an exercise bike, rested for 5 minutes before receiving their SLIT dose, and then completed the same exercise challenge 15 minutes after dosing. The results were negative across the board, indicating that the study protocol, unlike oral immunotherapy, did not require post-dose rest periods.

The foods were effective for up to six months when refrigerated and up to three months when stored at room temperature. In addition, foods such as nut milks and egg whites maintained their potency after being frozen and thawed, allowing patients to store their doses beyond the foods’ expiration dates.

The researchers noted that the study was limited by its single-center design, and further safety and efficacy analyses are needed. Nevertheless, the authors concluded that their protocol safely streamlined the SLIT dose escalation process and could make food allergy treatment more accessible to patients.

“Using real food in place of commercial skin test extracts in a modality of treatment that has been repeatedly shown to be highly effective brings us a step closer to being able to offer peace of mind to our patients with food allergy everywhere,” Dr. Windom and colleagues concluded. “Ease of administration through a squirt of a syringe, no routine exercise limitations before or after dosing, and no use of epinephrine make this akin to taking a daily vitamin.”