The briefing documents are out (PDF) for the highly anticipated advisory committee meeting for AR101, Aimmune’s immunotherapy for peanut allergy—and there are no surprises, Piper Jaffray analysts said. The company’s stock closed at $25.46 on Wednesday, a leap of 15% over the previous day’s close.
“Briefing docs right down the middle of the fairway,” wrote the analysts, noting that the agency stressed the difference between allergic reactions to the treatment and allergic reactions due to accidental exposure to peanuts. The phase 3 study tested the AR101 against placebo in 555 patients aged four to 55. Aimmune is seeking approval for the treatment in children and adolescents up to age 17, who made up nearly 90% of the study participants.
At the start of the trial, patients couldn't tolerate a fraction of peanut protein. After one year of treatment, 67% of patients who underwent immunotherapy could tolerate 600 mg of peanut protein—about two peanuts or a small bite of a peanut butter sandwich—compared to 4% who received placebo. This is more than four times the median amount of peanut protein that, in an accidental exposure, causes a reaction.
"What we're actually trying to protect folks against in the real world is about half a peanut," Aimmune CEO Jayson Dallas told FierceBiotech. "About 125 mg is the median dose that causes an accidental exposure to result in a systemic allergic reaction that may be life-threatening when people are out in the real world trying to avoid peanuts."
Patients taking AR101, which will be marketed as Palforzia if approved, had a higher rate of allergic reactions, epinephrine use and study dropouts than the placebo group: 89.1% versus 57.5%.
“But when looking at this therapy’s real utility—avoidance of AEs requiring treatment upon accidental exposure—Palforzia significantly lowers the incidence,” the analysts wrote.
After all, that’s what Aimmune is trying to do with Palforzia: reduce the risk of reactions when people stumble upon traces of peanut in their daily lives rather than in the controlled setting of a clinical trial.
“It sounds more dramatic than it is,” Dallas said, referring to concerns about the safety data. “These folks are coached that when they go on therapy, this is what is going to happen. They accept it and expect it … There is a misperception out there that this treatment is causing mass allergic reactions and folks going to the emergency room.”
The Allergenic Products Advisory Committee will meet Friday to review Palforzia.