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ANAHEIM, Calif. -- Peanut-allergic toddlers who stayed on an investigational, epicutaneous immunotherapy skin patch reached higher levels of peanut tolerance during the second year, according to the open-label extension of the EPITOPE trial.

In children ages 1 to 3 years assigned to the patch during the randomized portion of the trial, the percentage whose bodies achieved an eliciting dose (ED) of at least 1,000 mg without a reaction -- equivalent to about three or four peanuts -- grew from 74.7% at the initial 12-month analysis to 81.3% at 24 months, reported Matthew Greenhawt, MD, MBA, MSc, of Children's Hospital Colorado in Aurora.

The percentage who reached an ED of 2,000 mg or more increased from 52.4% to 63.8%, and the percentage defined as treatment responders increased from 77.4% to 83.9%, he said here at the (ACAAI) annual scientific meeting.

Among subjects initially randomized to placebo who switched to the active agent, 62.7% reached an ED of 1,000 mg or more and 36.5% reached an ED of 2,000 mg or higher during the open-label extension. The percentage defined as treatment responders was 68% in this group.

"The longer you are wearing this [patch], the more effects you're seeing, which is good," said Greenhawt.

Dubbed Viaskin (VP250), the investigational product exposes patients to 250 μg of peanut protein -- about 1/1,000th of a peanut kernel. The FDA for treating kids ages 4 to 11 years with peanut allergies, but developer DBV Technologies is now seeking an indication in children ages 1 to 3 years, where no approved product exists. (A peanut powder-based oral therapy, branded as Palforzia, is approved for children ages 4-17.)

"Epicutaneous immunotherapy has generally been viewed as being less robust in effect compared to oral immunotherapy, but also carrying much less in the way of allergic side effects," said food allergy specialist Scott Sicherer, MD, of the Icahn School of Medicine at Mount Sinai in New York City, who's familiar with the study findings.

"The main downside is having to wear an itchy sticker that can induce localized rash," he told 番茄社区, "although as pointed out in the current study, the local side effects are generally mild and wane with time."

Sicherer said "the findings are encouraging and confirmatory of some prior observations. Prior studies suggested that the approach was not working well for older children. Ultimately, this younger age group appears to benefit more readily while still having a great safety profile."

In an interview with 番茄社区, Greenhawt said patients may need to stay on the treatment indefinitely, as therapies have not been shown to cure peanut allergy.

Studies of oral immunotherapy in peanut allergy have shown that "most people, particularly those who are most sensitive to begin with, need to maintain some level of ingestion exposure or they can revert to being more allergic," Sicherer said.

Greenhawt declined to speculate about the potential cost of the treatment, but a estimated Viaskin may cost $6,500 a year. The Wall Street Journal last year that sales of Palforzia in older kids have disappointed, burdened by high costs and the need for multiple medical appointments; that powder-treatment lists at $890 per month. The newspaper added that for a lower cost, allergists can administer increasing doses of peanut powder on their own, a method that predates the approval.

Results of the initial international, double-blind EPITOPE trial were released at last year's ACAAI meeting and earlier this year in the New England Journal of Medicine. Researchers reported that more patients who took the active treatment compared with placebo achieved a treatment response (67% vs 33.5%, P<0.001).

The new 1-year extension trial, known as , tracked 175 of 208 participants in the initial trial who were randomized to the active therapy and 91 of 99 who were randomized to placebo. Participants will be tracked for a total of 3 years while they're taking the treatment.

Treatment-related adverse events were reported in nearly all participants (91.4% of those who started with the active therapy and 95.6% of those who started with placebo in the first year).

The patch can cause mild skin irritation, Greenhawt said, although patients can adjust to it. "A lot of these kids have sensitive skin to begin with," he told 番茄社区. "You can put a Band-Aid on them to get the same response."

Few adverse events were serious (4% in the continual active-treatment group and 2.2% of those who switched to the product), and none led to permanent treatment discontinuation. One participant who received the placebo in the first year experienced moderate treatment-related anaphylaxis on therapy.

As for availability, Greenhawt said the FDA has asked for more safety data, and a larger study with about 600 subjects is in the works.

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