Closing in on a Cure For Cat Allergy
This article first appeared in Allergic Living magazine. See the newer article on the therapy failing in a crucial study here.
THE ANCIENT Egyptians were said to revere the cat, glorifying it in hieroglyphs, depictions of deities and artwork. While today’s domestic kitty may not enjoy the same royal treatment, the feline still wields serious power: just being in the same room as one can trigger itching, coughing, wheezing and even a full-on asthma attack in the millions who have cat allergy.
The American Academy of Allergy, Asthma and Immunology says the condition affects an estimated 50 million Americans, including the 30 percent of those with allergic asthma who list cat dander as a key trigger.
Other than simply avoiding cats, immunotherapy, or allergy shots, is the only current treatment option for this allergy. The idea here is to re-train the immune system to accept the cat’s allergy-inducing protein rather than react to it as a dangerous invader.
To do so, the doctor injects small amounts of cat protein extract into the body over several visits, slowly increasing the dosage and then staying at a target level for three to five years. The hope is to achieve desensitization, or at the very least, greatly reduced symptoms.
The process is far from ideal. Not only does it require close to 100 injections, it is incredibly time-consuming, with untold hours spent at the doctor’s office. Not surprisingly, many patients simply quit going. Immunotherapy also always carries a reasonable risk of reaction, since the very thing a person is allergic to is being injected into the body. Anaphylaxis to immunotherapy, while uncommon, certainly has been reported, which is why patients are meant to wait at least half an hour in the doctor’s office after receiving an injection.
This is all that’s available today. However, the big news in the allergy and asthma research community is that a new, quick, and seemingly effective treatment for cat allergy looms large on the horizon, holding the promise of an end to the widespread grief.
Reports from a recently completed clinical trial speak for themselves. After just four shots of the new product – named Cat-SPIRE – patients experienced a significant decrease in symptoms when exposed to cat allergens. Not four shots per month or year, but just four shots in total, each taken one month apart. Two years later, the results were largely the same.
“That took us all by surprise,” says Mark Larché, an immunologist and professor of medicine at McMaster University in Hamilton, Canada. “To get a two-year effect after just one course of treatment, particularly when it’s only four injections, that’s very encouraging.” Larché is the co-founder of Circassia Ltd., a British biotech firm that is spearheading the product’s development along with the Canadian company Adiga Life Sciences, which is jointly owned by Circassia and McMaster University.
The key to Cat-SPIRE is the science behind the shot. Circassia scientists take the allergenic cat protein, called Fel d1, and break it down into basic parts called peptides. The building blocks of proteins are called amino acids, and peptides are strings of two or more amino acids. The Fel d1 protein is normally 162 amino acids long, while Cat-SPIRE contains seven synthetic peptides, each 15 amino acids in length, and each hand-picked to generate the desired response.
“Currently available immunotherapy basically takes the thing you’re allergic to and injects it into you,” says Steve Harris, CEO of Circassia and director of Adiga Life Sciences. Cat-SPIRE, he explains, was created by zeroing in on parts of Fel d1 that promote a regulatory, or non-allergic, immune response. By using fragments of Fel d1 created in a lab as opposed to the entire protein, fewer shots are needed, reactivity is lessened, increases in dosage are not required, and so far, the results have been impressive.
Patients have now been recruited for a final (or phase 3) trial that will confirm the shot’s effectiveness and also test whether giving eight injections instead of four makes any difference. About 1,400 cat-allergic individuals between the ages of 12 and 65 have enrolled in the trial, which is taking place in multiple sites across the United States, Canada and Russia over the next year.
Yet researchers already know that the shot won’t be equally effective for everyone. Dr. Harold Nelson, the principal investigator of the phase 3 trial, is quick to point out that patients in the previous trial showed an average symptom reduction of 50 percent. This suggests that Cat-SPIRE probably has a strong effect for many individuals, while others will likely benefit to a lesser degree.
Next: How study participants are doing now