Peanut allergy is one of the most common food allergies, affecting as many as 1 in 13 children. It is also one of the most serious allergies, capable of causing fatal and near-fatal reactions. Sensitive children can react not only as a result of peanut ingestion but often via inhalation or skin contact with allergens that can persist in the environment for months. Avoidance of peanuts is currently the only way to protect against such food allergy, with an emergency shot of epinephrine being used as a post-exposure rescue treatment. Growing awareness of the problem and its seriousness over the last several decades have resulted in the banning of peanut butter sandwiches from school lunchrooms and peanut hand-outs from most airplanes. But accidental exposure is still a serious problem and a source of anxiety and stress to the parents of sensitive children.
While a few allergists have developed their own approaches to oral immunotherapy for certain food allergies, no standardized oral immunotherapeutics have existed. In September, an advisory committee of the U.S. Food and Drug Administration voted to support approval of the first standardized oral immunotherapy treatment for peanut allergy, Aimmune’s Palforzia (AR101) — a standardized peanut powder product intended to desensitize the immune system to peanuts. An FDA decision is expected in January 2020.
Aimmune’s Biological License Application (BLA) for Palforzia is supported by two Phase 2 trials and follow-on studies conducted mostly in children and adolescents — the patients most likely to receive treatment. At the start of the one-year, placebo-controlled PALISADE trial, participants were unable to tolerate 100 mg or less of peanut proteins, the equivalent of about one-third of a single peanut. Patients treated with Palforzia were given higher doses of the therapeutic every two weeks until they reached a maintenance dose of 300 mg. After one year of therapy, 67% of the treated patients could tolerate at least 600 mg of peanut proteins compared to 4% of patients in the placebo group. Patients in another trial were able to tolerate up to 2,000 mg of peanut proteins. The median dose of peanut allergen in an accidental exposure that results in a systemic allergic reaction is about 125 mg.
Two of the advisory committee panelists expressed concerns that Palforzia might require life-long use. Aimmune is currently conducting a follow-on study to answer this question, with most patients who completed the PALISADE trial continuing to participate. Immunotherapies for grass pollen or bee venom have typically required about 3 years of continuous treatment before therapy can be stopped — otherwise the allergy re-emerges.
A few allergists question the need for Palforzia, given that they are already administering their own versions of oral immunotherapy using commercially available peanut flour. Others cheer Palforzia’s likely approval, saying that a standardized product is critical to ensuring a more predictable and safer experience for patients. Commercial peanut products can differ in their allergen content, as opposed to Aimmune, which is well characterized and able to provide dose-to-dose consistency.
Assuming that Aimmune’s product receives FDA approval in January, they are not likely to have the market to themselves for long. Paris-based DBV Technologies has submitted a BLA for a skin patch version of the peanut immunotherapy and benefitted from the Aimmune advisory committee decision with DBV Technologies’ stock price rising 6% in one day. DBV Technologies expects to receive FDA approval for their product in the second half of 2020.