LOS ANGELES – A peanut protein–bearing skin patch known as the Viaskin Peanut gave a continued strong performance for treatment of peanut allergy in children during the second year of an international study of this novel form of epicutaneous immunotherapy.
The clinical response rate in 6- to 11-year-olds after 1 year of treatment with the 250-mcg dose of peanut protein in the medical device was 57% in the phase IIb, double-blind, 22-site, international VIPES trial, as reported last year.
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After an additional year of treatment with the 250-mcg Viaskin Peanut in the open-label extension study known as OLFUS-VIPES, this rate climbed to 80%. Safety and tolerability of the device therapy remained excellent, Dr. Hugh A. Sampson said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
In adolescents and adults, however, the clinical response – while significantly better than placebo in VIPES – was less robust than in children, and it remained stable from year 1 to year 2. This is believed to be due to the greater plasticity of the immune system in children, observed Dr. Sampson, director of the Jaffe Food Allergy Institute at Kravis Children’s Hospital at Mount Sinai in New York and chief scientific officer at DBV Technologies, which is developing the Viaskin Peanut.
The ongoing phase III trial uses the 250-mcg dose of peanut protein – the highest of several doses studied in VIPES and OLFUS-VIPES – and is restricted to peanut-allergic children ages 4-11 years. Doses of peanut protein greater than 250 mcg will be explored in separate studies of adolescents and adults.
The clinical response rate in children on the 250-mcg Viaskin Peanut rose from 57% after 1 year to 80% – that is, 16 of 20 subjects – after 2 years. A clinical response in VIPES and OLFUS-VIPES was defined as nonreactivity to a dose of at least 1,000 mg of peanut protein – the equivalent of four peanuts – during a formal double-blind food challenge or at least a tenfold increase in the eliciting dose, compared to the original eliciting dose.
In VIPES, one-third of children on the 250-mcg device therapy for 1 year could tolerate at least 1,000 mg of peanut protein; after an additional year of open-label therapy, 60% of children were able to do so.
Among 6- to 11-year-olds, the median cumulative reactive dose of peanut protein was 44 mg at baseline, 444 mg after 12 months of using the 250-mcg Viaskin Peanut, and 1,444 mg at 2 years.
The children’s immunologic response to the Viaskin Peanut was impressive: A 40% reduction from baseline in peanut IgE at 2 years, along with a ninefold increase in protective peanut-specific IgG4.
The skin patch consists of a dried allergen – in this case, peanut protein – which is made electrostatically adherent to a membrane on a Band-Aid–like chamber. A set of patches is placed on noneczematous skin on a child’s back and on the inner upper arm of older patients. Moisture emitted from the skin gradually causes the protein allergen to solubilize and get absorbed into the outer layer of the skin. It is then picked up by antigen-presenting Langerhans cells and transported to regional lymph nodes for deactivation. The patches are changed daily.
“It appears that we need to look at the skin as a tolerogenic organ when it’s uninflamed,” Dr. Sampson observed.
Compliance with treatment was in excess of 96% in both VIPES and OLFUS-VIPES. There have been no serious treatment-related adverse events and no need for the use of epinephrine. Side effects have been limited to occasional mild to moderate application site reactions easily managed with antihistamines and/or topical steroids, according to Dr. Sampson.
The double-blind VIPES study included 207 subjects with documented peanut allergy. OLFUS-VIPES, which will continue for 1 additional year of open-label therapy, includes 171 of the original 207, including 97 children, 49 adolescents, and 25 adults up to age 55 years.
“We’ll see if there’s continued improvement in children through the third year or it levels off, but based upon the immunologic parameters I think it’s having continued effect,” the pediatric allergist said.