In February, news broke that a phase 3 clinical trial evaluating an oral therapy for severe peanut food allergy had concluded with promising results. Now, the full details of the study have been published in the prestigious New England Journal of Medicine, putting the treatment one step closer to approval by the US Food and Drug Administration (FDA).
There are currently no approved treatments that prevent or reduce the symptoms of any type of food allergy. Individuals with extreme peanut allergy – characterized by a potentially deadly inflammatory immune response to peanut protein – must remain constantly vigilant in order to avoid even the most minimal accidental exposure, and many must keep an epinephrine injector on hand at all times.
The experimental treatment, called AR101 for the time being, is not a one-and-done cure for peanut allergies, but rather a daily regimen of purified peanut protein-filled capsules that reduces the body’s reaction to peanut protein through sustained exposure.
"This is not a quick fix, and it doesn't mean people with peanut allergy will be able to eat peanuts whenever they want. But it is definitely a breakthrough," Dr Jay Lieberman, AR101 investigator and vice chair of the American College of Allergy, Asthma and Immunology Food Allergy Committee, said in a statement.
Aimmune Therapeutics, the biotech company behind AR101, are planning to submit a new biologics drug application by the end of this year.
"The hope would be to have a treatment available in the second half of 2019. If that happens, people who receive and are able to tolerate this treatment should be protected from accidental exposures," Dr Lieberman added.
In the phase 3 trial, AR101 was assessed in 496 children aged 4 to 17 and 55 adults aged 18 to 55 with allergies so severe that they could not ingest more than 100 milligrams of peanut protein – equivalent to about one-third of one peanut – without experiencing a moderate to extreme reaction. Half of the participants in each age group were randomized to receive daily AR101 pills of increasing doses until they reached 300 milligrams, and then remained on that dose for 24 weeks. The other half were given placebo pills.
Nearly one year after participants were given their first pill, they underwent a peanut protein food challenge. Remarkably, 67 percent of children given AR101 could tolerate ingesting a single dose of 600 milligrams of protein without unpleasant effects, and over 50 percent could handle the maximum tested single dose of 1,000 milligrams. Only 4 and 2.4 percent of placebo patients could match these feats, respectively. (The fact that any placebo subjects could is likely due to the poorly understood mechanism by which some kids grow out of food allergies.)
Sadly, the regimen did not significantly change the immune response of adult subjects.
"On average, the participants were able to tolerate a 100-fold higher dose of peanut at the end of the study than they did at the beginning,” stated study co-author Dr Stephen Tilles.
"Our hope when we started the study was that by treating patients with the equivalent of one peanut per day, many would tolerate as much as two peanuts. We were pleased to find that two-thirds of the people in the study were able to tolerate the equivalent of two peanuts per day after nine to 12 months of treatment, and half the patients tolerated the equivalent of four peanuts."
Long-term follow-up studies of subjects from this study and previous trials are ongoing, but the investigators are confident that AR101 pills could provide lasting protection.
Patients would have to take the medication indefinitely to maintain the effect.