Clinical Trial Suggests Way to Fight Peanut Allergy
For some children, even trace amounts of peanuts can be deadly. But so far, kids suffering from peanut allergies have no treatment options other than avoiding the legumes completely. The results of a new clinical trial may change that. Scientists have found that feeding allergic children small amounts of peanut protein every day, an approach known as oral immunotherapy, can help them lead a normal life.
"This is a very important first step," says Gideon Lack, a pediatric allergist at King's College London, who was not involved in the work. "But I don't think it is ready to go into clinical practice."
About 1% of children in high-income countries like the United States and the United Kingdom suffer from a peanut allergy. Their immune system reacts to proteins found in the nuts and in severe cases that reaction can cut off breathing or lead to a sudden drop in blood pressure, starving the organs of oxygen. The condition puts a lot of stress on families, because even children who have reacted mildly to peanuts in the past can suddenly have a life-threatening incident, says Andrew Clark, a pediatric allergist at Cambridge University Hospitals NHS Foundation Trust in the United Kingdom and one of the researchers involved in the trial. Some studies have shown that exposing children to increasing doses of peanuts can desensitize them, but few big trials have been done. Some studies in the 1990s tried injecting the antigen into the skin. But side effects were severe and in one study a patient died because of a dosing error. "Because of that, people haven't touched this for 10, 20 years and are only now approaching it again," Clark says.
Clark and colleagues started with 49 allergic children aged 7 to 16 years. The kids’ meals included a small amount of peanut flour, with the dose slowly increasing from 2 milligrams to 800 milligrams (equivalent to about five peanuts). A control group of 46 children who had a peanut allergy avoided the nuts altogether. After 6 months, 24 out of the 39 children in the treatment group who completed the study could tolerate 1400 mg of peanut protein without showing a reaction, but no one in the control group could, the authors report today in The Lancet. Many children suffered from nausea or vomiting, but in general these side effects were mild and occurred only in the first days after an increase in the dose. "We feel we've found a regime that works very well," says Clark, who hopes to offer the treatment as part of a "named patient program" within a year. Such programs allow doctors to use therapies that are not approved on individual patients if no other treatment exists. "I feel we have an obligation to act on our results," he says.
A group led by Kirsten Beyer, a pediatrician at the Charité University Medicine Berlin, recently finished a similar trial and is analyzing the results. Beyer criticizes the study for not using a placebo treatment in the control group. "But it is a big step in the right direction," she says. "We urgently need more studies on treating peanut allergy."
Lack also praises the study for being larger and more rigorously conducted than previous trials. But the benefits of the treatment are likely to be short term, he warns. "If you stop eating the peanuts for a few weeks or even a few days and you are reexposed, you may have a severe allergic reaction." Because of this danger, avoiding peanuts may still be the better option, he argues. But Clark says that participants seemed to tolerate short gaps, and he hopes to change some of the kids who have now been in treatment for 2 years to a weekly dose.
Hugh Sampson, an allergy researcher at Mount Sinai Hospital in New York City, says that more studies are needed to address unanswered questions. For instance, what the optimal dose is, whether there are chemicals that can make the therapy safer, and whether there are long-term adverse consequences of the therapy. "While this study adds to the growing data on the potential utility of oral immunotherapy for treating food allergy,” he writes in an e-mail, “I am not sure that this study brings us closer to the answers.”