AT 2015 AAAAI ANNUAL MEETING
HOUSTON (FRONTLINE MEDICAL NEWS) – A peanut protein–bearing skin patch showed considerable promise in the largest randomized trial to date of any potential treatment for peanut allergy.
One year of treatment with the investigational proprietary Viaskin Peanut skin patch raised the threshold of exposure to peanut protein required to elicit an allergic reaction to a level that patients and families would consider life changing, Dr. Hugh A. Sampson said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
“One of the biggest problems for the family of a patient with peanut allergy is the fear of getting contamination. If they could rest assured that they could tolerate something like a gram’s worth of contamination with peanut protein, much of that concern would go away. They could go to restaurants and birthday parties. They still need to be vigilant and tell people they’re peanut allergic, but the chance of these low-level contaminations that lead to most of the reactions we see would largely be taken care of,” said Dr. Sampson, professor of pediatrics, allergy, and immunology and dean for translational biomedical research at Icahn School of Medicine at Mount Sinai, New York.
He presented the findings of a phase IIb randomized, double-blind, multinational, placebo-controlled trial of what is being called epicutaneous immunotherapy. The trial involved 221 subjects with documented peanut allergy. Roughly half were aged 6-11 years; the rest were adolescents and adults up to age 55. They were randomized to one of four study arms: the skin patch at a dose of 50, 100, or 250 mcg or a placebo patch. As a requirement for study participation, all subjects had to have a peanut protein reaction–eliciting dose of 300 mg or less on baseline formal oral peanut challenge testing; half of the children reacted to 30 mg or less.
The primary endpoint was the ability to tolerate on a repeat oral challenge at 1 year either at least 1 g of peanut protein or 10 times the amount they tolerated on baseline testing. In the overall study population, the 250-mcg patch was the top performer. It was the only patch dose significantly better than placebo: 50% of all patients on the 250-mcg patch met the primary endpoint, compared with 25% of placebo-treated controls.
Peanut allergy typically starts early in life, so it’s noteworthy that the children in the study had a markedly more robust response to epicutaneous immunotherapy than the older patients. Indeed, among the 6- to 11-year-olds, all three patch doses outperformed placebo. The mean cumulative dose of peanut protein required to elicit a reaction on structured oral challenge testing was 1,121 mg greater at 1 year than at baseline among children on the 250-mcg patch, 570 mg greater with the 100-mcg patch, and 471 mg greater than at baseline among those using the 50-mcg patch.
Similarly, a robust dose-dependent increase was seen in protective peanut-specific IgG4 levels in response to 1 year of epicutaneous immunotherapy. The median level of this biomarker of therapeutic benefit climbed 19-fold over baseline in children on the 250-mcg patch, 7-fold with the 100-mcg patch, and 5.5-fold with the 50-mcg patch.
The compliance rate with patch therapy was greater than 96%. Only 2 of the 221 participants dropped out of the study due to adverse events, both because of a flare of atopic dermatitis around the patch site. There were no serious adverse events in the study.
The trial is being extended for a second year of immunotherapy. “My anticipation based on what we see with other forms of immunotherapy is that we might very well see even more protection,” according to Dr. Sampson.
In an interview, he said he’d like to see the skin patch studied at doses above 250 mcg in adolescents and adults.
“I would also love to see epicutaneous immunotherapy looked at in very young children,” he added. “You get a much better response, and it may be longer lasting because we think that the immune system in an infant is much more plastic than it is once they get older. Trying to reverse a set response is much more difficult.”
The skin patch is about the size of a small, round Band-Aid. It is placed over the back or inner upper arm and changed daily. The concept is that as humidity develops under the patch, a small amount of peanut protein permeates the outer skin. Langerhans cells then pick it up and transport it to regional lymph nodes, where T cells can activate desensitization.
“I think this concept of using a low amount of protein in a convenient, safe way could change the way we do immunotherapy,” Dr. Sampson predicted.
Asked to comment, peanut allergy researcher Dr. Brian P. Vickery of the University of North Carolina, Chapel Hill, agreed with Dr. Sampson’s assessment that patch therapy could be a game changer, especially given that there is no FDA-approved treatment for peanut allergy.
“Right now the standard of care is avoidance. So anything that improves upon that to allow a margin of safety that lets a patient get along in the world with the reassurance that a contamination event up to, say, a gram would be well tolerated would be transformative,” he said.
