Allergy Medicine: The Next Generation
Even as prescription-only nasal treatments are helping many allergy sufferers manage their reaction to pollen, a new generation of medications is in the regulatory pipeline, awaiting the U.S. Food and Drug Administration’s scrutiny.
Pollen, which contains semen spores, is what plants use to mate. But humans get in the way. The histamine released from mast cells, which line the skin and mucous membranes, causes the symptoms, which are specific to where the pollen lands. In the eyes, histamine will produce tears, redness and itching. In the nose, sneezing and itching. In the bronchial tubes, asthma.
Dr. Bobby Q. Lanier, president-elect of the American College of Allergy, Asthma and Immunology in Chicago, says the body confuses pollen with a protein shed by parasites. At the heart of this response is an antibody called IgE, or immunoglobulin E. When the mast cells greet pollen, IgE is signaled and trips a switch to release histamine.
Needless to say, this hearty response of the immune system doesn’t make the majority of allergy sufferers feel any better.
Now Schering Corp. has submitted for FDA approval a compound dubbed Clarinex, described as an improved version of Claritin. And Sepracor pharmaceuticals has developed a more potent antihistamine called norastemizole.
But the compound causing the most excitement is one with a radically different approach. It’s a vaccine that comes closest to treating the root of the allergic response to pollen, by blocking IgE.
This development marks a turning point for immunologists. Scientists at Genentech and Novartis devised a way to cover, or hide, the antibody at its base on the mast cell, much as you might put a sheath on a knife to keep the sharp point at bay, said Lanier.
It’s a complicated strategy to develop a so-called monoclonal antibody vaccine. Scientists inject the human allergic antibody into mice, and these animals wage their own antibody response. The new animal antibody is then extracted from the animal’s bone marrow. Most of the mouse antibody is removed, except for a critical piece where the IgE antibody docks itself onto the mast cell.
This piece is coupled with a human antibody that acts as the guided missile for the human IgE. After an injection, the missile finds its target on the mast cells and lays a protective cover over the docking area.
The compound, if approved, would be expensive, costing as much as $1,000 a month, according to Dr. David Rosenstreich of Alert Einstein College of Medicine. The treatment would require injections every four to six weeks.
The development of allergy-fighting compounds began during World War II. In 1939, European scientists developed Benadryl, and the substances that have come along since have been versions of it. But those medications caused drowsiness.
Antihistamines that don’t cause drowsiness have been available by prescription since the late 1980s. The FDA is considering moving them to over-the-counter status.
Prescription nose sprays like Flonase and Nasacort have been on the market since the early 1990s. They contain potent steroids that also block release of histamine and reduce inflammation.
