A sufferer of a severe peanut allergy must constantly be on guard. Even the slightest exposure to the legume--perhaps from a poorly washed knife or a kiss from a peanut eater--can lead to a life-threatening reaction or even death. But research published this week by the New England Journal of Medicine offers new hope for the millions of people who must avoid all contact with the nut. Trials of a novel drug indicate that it can increase the amount of peanut exposure an allergic person can tolerate, thus offering protection against accidental ingestion.

A team of researchers led by Donald Leung of the National Jewish Medical and Research Center and Hugh Sampson of Mount Sinai School of Medicine in New York City recruited 82 people with peanut allergies for the study. They first tested how much peanut flour caused an allergic reaction--which is characterized by symptoms including nausea, wheezing, vomiting, coughing or the appearance of hives--for each patient. The volunteers then received injections of either a placebo or doses of the drug TNX-901 for four weeks. (Neither doctor nor patient knew which was administered.) At the end of the study, the scientists again tested the subjects' reactions to peanut flour. The team found that those sufferers who received the highest dose of TNX-901 could tolerate 15 times as much peanut flour--about the equivalent of eight or nine nuts--without experiencing a reaction. "We believe that patients would have to continue the injections for the benefits to persist and they still would need to be careful about what they eat," Sampson says. "But, because the amount they could consume without serious reaction would be greatly increased, the fear of accidental ingestion that detracts from quality of life for many patients would be eliminated."

Unlike current treatments that are administered after the onset of an allergic reaction, TNX-901 serves to inhibit the response before it begins. The drug consists of a genetically engineered antibody that binds to IgE, an antibody responsible for starting the body's allergic response. "Our results indicate that the anti-IgE antibody could become the first preventative medicine for peanut allergies," Leung comments. Approval of the drug by the Food and Drug Administration is still a few years away, however. In addition, legal tussles between three competing drug companies have further stalled future trials that could lead to FDA endorsement of TNX-901.