A skin patch designed to increase protection against peanut allergy reactions is proving to be more effective in kids than teens or adults, and a longer treatment period is also proving important, according to data presented at the recent American Academy of Asthma, Allergy and Immunology conference.
Researchers tried using the Viaskin patch, which exposes wearers to a small amount of peanut protein on patients, for a total of three years. Results of the year-long first part of that study, which was double-blinded and placebo-controlled, were first released in 2014. This latest set of data is from the extension of that first trial, in which all patients were given the opportunity to go on the higher dose patch (250 micrograms of peanut protein) for two years.
At the end of the study, 83.3 percent of children between the ages of 6 and 11 met the study’s goal of being able to tolerate 10 times the amount of peanut they could tolerate at the beginning of the study, or at least 1,000 milligrams of peanut protein (approximately five peanuts). At the end of one year on the patch, only 53.6 percent of kids met this goal.
Out of the 171 patients in this extension study, 97 were children and the rest were teenagers and adults. But while researchers analyzed data for all age groups, the patients older than 11 didn’t have as significant an improvement in their ability to tolerate peanuts at the end of the three years.
“Our feeling is, the younger we get them, the better,” Dr. Hugh Sampson, director of the Jaffe Food Allergy Institute at Mount Sinai in New York, said at a news conference. “But that doesn’t say that we can’t do something in the adult population.” He agreed that the higher dose and longer term were also important factors.
Sampson explained the age-related results discrepancy by noting that key cells involved in the therapy, the Langerhans cells, are found around hair follicles. “When you’re born, you have a certain number of hair follicles, and as you grow, those spread apart. So putting the same-sized patch on a small child, where the hair follicles are close together, is exposing more of the antigen to Langerhans cells than an adult, where they are spread apart,” said Sampson, who also acts as the chief scientific officer for DBV Technologies, the company that has developed patch.
The company is now focusing its two Phase 3 clinical trials on this younger age group. “This does not mean that we’re not going to evaluate the other age groups further,” Dr. Luis Salmun, DBV’s vice president of medical affairs, North America, told Allergic Living. “We’re in the process of very soon launching our first trial in children ages 1 to 3, and at the same time, we’re at the process of evaluating how to best study the adolescents and adults.”
Results from the two phase 3 studies should be available by the second half of this year, after which time Salmun expects to be able to apply for FDA approval. But the company is still trying to figure out one key aspect of the treatment: Will patients ever be able to take the patch off for good?
“This is not something we can come to a conclusion on yet,” says Salmun, adding that researchers did take some of the patients off the treatment for two months to see if they had developed what’s called “sustained unresponsiveness” – but that data has not yet been published.
Another aspect that’s not clear is whether the other 17 percent of kids who did not gain tolerance after three years on the treatment ever would. “For some of the children that did not qualify as responders by the end of study, changes in CRD (cumulative reactive dose) and serological markers were observed, but they were not significant enough to qualify as responders as measured by the study’s endpoint.” Salmun wouldn’t speculate on what would happen if these kids stayed on the patch for longer.
The Viaskin patch is placed on a person’s back and uses unique technology that takes advantage of the skin’s strong immunological properties to deliver the allergen to the body in minuscule amounts – for example, it would take 1,000 patches to make up a full peanut, says Salmun.
Overall compliance in the study was 95 percent, which is very high. Still, 2.3 per cent of patients did drop out because of symptoms.
In addition to peanut, DBV Technologies is in phase 2 trials for a milk allergy patch, and has an exploratory trial for eosinophilic esophagitis on the go. There are also pre-clinical studies under way for egg allergy. –with files from Gwen Smith
Allergic Living’s full list of conference articles here.