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Study Evaluates Experimental Treatment for Cat Allergy


National Jewish Health allergist Harold Nelson, MD, is evaluating a treatment for cat allergies that could reduce treatment from three years and more than 100 shots to four months and as few as four shots. The study will evaluate a new form of immunotherapy, developed by the company Circassia and called ToleroMune®, that uses small pieces of the irritating substance produced by cats instead of the full-sized protein that causes symptoms in allergic people.
“Immunotherapy, or allergy shots, is the only treatment that can actually treat the underlying disease, rather than just the symptoms,” said Dr. Nelson, principal investigator for the international study. “Use of it has always been limited by the long treatment required. If the current study confirms earlier findings, it could be a major step forward for allergy treatment.”

Cat allergy is one of the most common allergic disorders, affecting an estimated 10 million people in the United States. It is also a common trigger for people with allergic asthma. A single protein, known as fel d 1, secreted by glands in cats’ skin, causes almost all cat-allergy symptoms.

Traditional immunotherapy involves the injection of allergenic proteins, whether from cats, dogs, pollen or other allergenic sources, into patients over an extended period. By gradually increasing the amount of protein injected, and continuing the process for up to three years, immunotherapy eventually desensitizes most patients so that they no longer react to the protein. In addition to taking years, the traditional approach has some danger of a significant allergic reaction as the protein doses are increased.

The Toleromune approach involves the single injection of seven small protein fragments derived from fel d 1 instead of the entire protein. These fragments stimulate T cells that can dampen the immune response, but are not large enough to provoke an allergic reaction.

Previous studies have shown that four shots administered once monthly effectively desensitized allergic patients, most of whom remained desensitized a year later. The current study, which will seek to enroll 1,200 patients at National Jewish Health and more than 100 centers in the U.S., Canada and Europe, will compare placebo treatments with four-shot and eight-shot regimens.

For more information, call 303.398.1911 or email

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