Peanut allergies affect between 1 and 3% of the US population. Associated with a heightened risk of severe anaphylactic reactions, oral immunotherapy is the only existing treatment, requiring patients to eat small, slowly escalating portions of the allergen under medical supervision. Now however, researchers from Stanford University in California have developed a promising new treatment in the form of a singular antibody injection.
Allergies are triggered by interleukin-33 (IL-33), an immune system protein. This protein triggers the production of antibodies called immunoglobulin E (IgE), which travel to immune cells that then produce chemicals that result in allergic symptoms such as difficulty breathing, itchiness of the mouth and throat and, in severe cases, anaphylactic shock.
Each allergy responds to a specific IgE antibody. This means that those with peanut allergies have different types of IgE antibodies to those allergic to eggs or milk. It also means that a person who has several allergies at the same time has several different IgE antibodies at once. Thus, the antibody injection developed by the researchers, known as Etokimab, works by inhibiting IL-33 proteins specific to peanut allergies.
For the study, the researchers recruited 20 participants, each with a severe peanut allergy. While 15 received a single injection of Etokimab, 5 received a single injection of a placebo. Consuming a small amount of a peanut protein under supervision 15 days later, the researchers found that 11 of those who took Etokimab (73% of the total group) were able to eat 275mg- around a nut’s worth- of peanut protein with no adverse reaction. Meanwhile, none of the participants who received a placebo were able to do this.
The researchers also took blood samples from each participant on the same day, finding that those in the Etokimab group had significantly less peanut-specific IgE antibodies and other immune markers in their blood than the placebo group.
To see whether these results were sustained, the researchers conducted more tests on participants 45 days. Of those available to be tested, 4 out of 7 who took Etokimab passed again, whereas nobody in the placebo group did.
The researchers now hope to repeat the study with more participants and identify biomarkers indicative of who could most benefit from the treatment. They also hope to determine the most appropriate treatment timeline and dosage for the antibody, as well as the injection’s potential to treat other allergies too.