Having a food allergy requires more than a change in diet. For many people with a moderate to severe allergy, it requires a change in lifestyle. In the United States, one of the most common food allergies is peanuts, an ingredient found in everything from lunch sandwiches to chili. In 2014, two percent of children in the United States under the age of 18 had a peanut allergy. It is the most common cause of anaphylaxis, a reaction in which a person experiences itchiness, swelling of the throat, plummeting blood pressure, fainting, or vomiting. When severe reactions are not treated with an emergency injection of epinephrine, the effect can sometimes be fatal. While there is no cure for a peanut allergy, scientists are working on various treatments that can at least reduce the severity of reactions to the nut. Immunotherapy, where the patient is exposed to very small amounts of peanut protein over time, has garnered the attention of the science community in the past decade. While many of these studies have focused on oral doses of peanut protein taken in a pill, for example a new clinical trial shows that one solution may be skin deep. The study, published in the Journal of the American Medical Association, on more than 200 peanut-allergic patients. Hugh Sampson of the Icahn School of Medicine at Mount Sinai School in New York led the research. Sampson is also the part-time, chief scientific officer at DBV Technologies, which makes the Viaskin Peanut patch and funded the study. For the study, 221 participants between the ages of 6 and 55 years old were divided into four groups. One group received a placebo patch, which contained no peanut protein. The second, third, and fourth groups wore peanut patches containing either 50, 100, or 250 micrograms of peanut protein. The patients wore the patch on the back of their arm or their back every day for a year. In the end, 97 percent of the study participants 207 patients completed the full year. The patch resembles a small round Band-Aid. When the patch is applied, the bodys natural water loss helps the peanut protein absorb the peanut protein inside, which is then absorbed into the skin and picked up by Langerhans cells. These cells then transport the protein to regional lymph nodes, where they educate regulatory T cells that might lessen an allergic response. Sampson noted that the amount of peanut protein used in the study was very small when compared to the amounts used in other trials for oral immunotherapies. One oral immunotherapy, for example, gave patients up to two grams of peanut protein. To be classified as a responder to the patch treatment, patients had to be able to tolerate 1,000 milligrams of the peanut protein at the end of the year, or 10 times more peanut protein than the amount that initially triggered their reactions at the beginning of the study. After a year, a significant number of responders in the group wore the patch with 250 micrograms of peanut protein when compared to those wearing the placebo patch. There was no significant difference between those wearing the patches with 50 or 100 micrograms and the placebo group. While Sampson said the results were in line with what his team was expecting, he added that there were some interesting findings when looking at the different age groups. Children, or those 6 to 11 years old, had a better response to the patch when compared to the adolescent and adult groups. The result could be because of where the patch was placed the patch was placed on the backs of the children while others wore the patch on the back of their arms or the number of Langerhans cells exposed to the patch. We know that the Langerhans cells that pick up the protein tend to congregate around the hair follicle, said Sampson. Basically, you get so many hair follicles, and when you get older they spread out. So, it could be that using the same sized patch on an adult verses a child could mean that youre not exposing as many Langerhans cells in an adult as you would a child. These are some questions Sampson is looking at as they continue phase three of the patchs clinical trial. (There are usually four stages of clinical trials.) There are usually four stages of clinical trials, with phase three typically looking for side effects that may have gone undetected in earlier phases. The length and size of phase three trials are also larger than previous stages, incorporating hundreds to thousands of participants for up to four years. And even though the focus is on the patch, other forms of immunotherapy remain viable. Until we find the best way do to it, we keep looking at everything, Sampson said. While patients will most likely never be able to gobble up a handful of peanuts, Sampson said there might be a way to desensitize those with peanut allergies to small amounts of the nut. We are trying to get them to be able to go to restaurants and friends houses without them constantly worrying about a reaction, Sampson said.
Real Clear Science, 16 November 2017 ; http://www.realclearscience.com