By Karen Pallarito
Sunday, September 28, 2008 12:00 AM
SUNDAY, Sept. 28 (HealthDay News) -- A vaccine that protects against the miserable symptoms of ragweed allergy for a longer period of time -- and with fewer injections -- could be available in the coming years.
Unlike traditional allergy vaccines that are given weekly for several months, new formulations would require only a few injections and would offer longer-lasting relief.
"What you would hope is that you would get fewer injections less often, less likelihood of an allergic reaction and the same or better improvement in your symptoms," said Dr. William C. Howland III, an allergist and medical director of Lovelace Scientific Resources in Austin, Texas.
Howland has presented research at an American College of Allergy, Asthma & Immunology meeting showing that just four injections of an investigational ragweed vaccine, called Pollinex Quattro, were safe and effective.
Separately, a research team led by Dr. Peter Creticos, clinical director of the Johns Hopkins Asthma and Allergy Center in Baltimore, has led pilot testing of another ragweed vaccine, called Tolamba, developed by Berkeley, Calif.-based Dynavax Technologies Corp. Those results were published recently in theNew England Journal of Medicine.
"Our study was able to demonstrate that after a concise six-week, six-injection regimen, we were able to shut off seasonal symptoms for at least the two seasons we followed the patients in the study," Creticos said.
Ragweed is a type of weed that grows throughout the United States but is most common in the eastern states and in the Midwest. Among Americans who are allergic to pollen-producing plants, 75 percent are allergic to this particular weed, according to the Asthma and Allergy Foundation of America.
Ragweed season typically runs from mid-August to October and is a significant cause of fall allergy symptoms, says the American Academy of Allergy, Asthma & Immunology.
Antihistamines help some people achieve relief from their symptoms, including runny or stuffy noses, sneezing, and itchy eyes, nose and throat. But when these medications don't work, allergy shots are the next line of treatment.
Allergy vaccines are highly effective but have certain drawbacks, allergists say, including the number of shots required to build up an immune response.
"It takes between six and 18 months of weekly injections to reach the maximum effect, so people are coming in every week, and they get an injection," Howland explained.
In addition, it's recommended that patients wait in their doctor's office 30 minutes after each injection to be monitored for any adverse reactions that may occur.
The new wave of investigational vaccines have been tweaked to be more effective in fewer doses and to reduce the incidence of immediate side effects.
Early results look promising.
Howland and his colleagues, for example, studied different doses of a ragweed extract and their effect on antibodies in the bloodstream. People with allergies produce an antibody called immunoglobulin E, which sets off a cascade of chemicals to fend off a perceived allergen, such as ragweed. This chemical response triggers the allergic symptoms that people experience. Another antibody in blood, called immunoglobulin G, fights infection.
"What the study showed was that the G antibodies increased proportionate to the strength of the injections given," he said. "So, the weaker injection had less of an effect, and then the medium had more, and the highest dose had the highest effect on the G antibodies."
However, don't expect new-and-improved vaccines to pop up in your doctor's office this ragweed season. Vaccine makers have to clear several hurdles first.
Allergy Therapeutics PLC, the U.K.-based maker of the Pollinex Quattro vaccine, reported that the U.S. Food and Drug Administration had placed a "hold" on its clinical studies while the agency reviewed a report of a rare adverse event. The company noted that a physician involved said the event was "possibly related" to the study drug. Last November, the company said it had met with the FDA, submitted information, and would continue to work with the agency to lift the hold.
Meanwhile, Creticos said a large, multi-center trial replicated findings of the Tolamba pilot study that his team led. Additional studies are continuing.
Dr. Thomas B. Casale, chief of the Division of Allergy and Immunology at Creighton University School of Medicine in Omaha, Neb., expects it will take another couple of years for these vaccines to become available, assuming, he added, that the next wave of clinical trials show that these approaches are safe and effective.
Until there are better treatments, people with ragweed allergy can minimize their exposure by keeping windows in their cars and homes closed to prevent pollen from drifting in, according to the American Academy of Allergy, Asthma & Immunology. And take a shower after spending time outdoors, because pollen can collect on your hair and skin.
The Asthma and Allergy Foundation of America can tell you more about outdoor allergies.
SOURCES: Thomas B. Casale, M.D., professor of medicine, andchief, Division of Allergy and Immunology, Creighton University School of Medicine; Omaha, Neb.; William C. Howland III, M.D., allergist, and medical director, Lovelace Scientific Resources, Austin, Texas; Peter Creticos, M.D., clinical director, Johns Hopkins Asthma and Allergy Center, Baltimore; Asthma and Allergy Foundation of America, Washington, D.C.; American Academy of Allergy, Asthma & Immunology, Milwaukee; Allergy Therapeutics PLC, West Sussex, United Kingdom; Dynavax Technologies Corporation, Berkeley, Calif.