Peanut allergy reactions cause 50-100 deaths per year in the United States. The Early Show medical correspondent Dr. Emily Senay reports.
The monthly shots are not a cure. But doctors believe the drug should let these people avoid severe complications if they unknowingly eat one or two peanuts, the typical accidental exposure.
The peanut allergy drug is designed to catch hold of immunoglobulin-E, or IgE, a molecule that plays a major part in asthma and allergies.
In a study, 84 people with immediate allergic reactions to peanuts got monthly shots of either a placebo or TNX-901 for four months. There were three different doses of TNX-901; neither doctors nor patients knew who got what.
Those on the highest dose could handle an average of almost nine peanuts' worth of peanut flour at the end, compared with about a half-peanut at the start. And five of them ate the equivalent of 24 peanuts without reacting.
The drug also protected people from the even tinier amounts of peanuts that can be present in the air. In addition, several participants reported that other food allergies were lessened, and hay fever symptoms disappeared.
Shelley Schneiderman Ducker, spokeswoman for Genentech Inc., one of the developers of the drug, said TNX-901 is likely to expensive, but she would not be more specific.
How TNX-901 works...
When a person who has a peanut allergy, ingests peanuts they normally experience some degree of anaphylaxis, an allergic reaction which may include the following symptoms: nausea, vomiting, diarrhea, abdominal pains, hives, angioedema, bronchospasm, hypotension, loss of consciousness, and death.
Here is what happens internally: the body is exposed to the allergen (peanuts) and certain cells begin to release IgE. IgE binds to mast calls which triggers the release of histamine and other mediators of anaphylaxis. Histamine is one of the substances responsible for the symptoms on inflammation and is the major reason for running of the nose, sneezing, and itching in allergic rhinitis. It also stimulates production of acid by the stomach and narrows the bronchi or airways in the lungs.
However, TNX-901 is an anti-IgE agent (or monoclonal antibody to IgE). Which means when an allergen (peanuts) are present in a person's system causing IgE to be released; TNX-901 prevents IgE from becoming binded to mast cells, thereby preventing anaphylaxis.
TNX-901 is on the fast track for federal approval, but a fight among Genentech, Tanox Inc. and Novartis Pharmaceuticals has held up the next round of tests.
Meanwhile, other investigational avenues remain open and active. Two approaches to the induction of immune tolerance have produced encouraging results in mice. One approach uses recombinant peanut antigens that have a reduced capacity to be bound by IgE. The other uses short synthetic peptides that involve T-cell specificity but cannot crosslink IgE. If these agents prove safe and effective in humans, they might be even more useful than anti-IgE therapy.
According to the Web site of the Food Allergy & Anaphylaxis Network:
- 2 to 2 1/2 percent of the general population suffers from food allergy, or between 6-7 million Americans. Up to 3 million Americans suffer from peanut or tree nut allergy.
- 8 foods account for 90 percent of the allergic reactions. They include peanuts, tree nuts (walnuts, pecans, etc.), fish, shellfish, eggs, milk, soy, and wheat.
- Peanuts are the leading cause of severe allergic reactions, followed by shellfish, fish, tree nuts, and eggs.
- Physicians are reporting an increase in the number of food-allergic patients in the country.
- Individuals with food allergies and asthma appear to be at an increased risk for severe allergic reaction.
- Most individuals that have had a reaction ate a food that they thought was safe.
- Food allergy is the leading cause of anaphylaxis outside the hospital setting, accounting for an estimated 30,000 emergency room visits and 2,000 hospitalizations each year.
- It is estimated that as many as 150-200 people die each year from food allergy-related reactions; approximately 50 people die from insect sting reactions.