Nothing to Sneeze At: New Strategies for Controlling Cat Allergy

in Asthma, Indoor Allergies, News, Pets
Published: October 13, 2020
New Strategies for Controlling Cat Allergy. Cat getting it's face rubbed.
Photo: Getty

Updated Feb. 1, 2023 – When it comes to cat allergy, there’s only one sure way to avoid symptoms – stay away from cats. But many cat lovers with allergies would rather live with the sniffling, sneezing and wheezing than live without their beloved pet. 

“As I tell people with cat allergies, the treatment of choice is removal of the cat,” says Dr. Michael Blaiss, executive medical director of the American College of Allergy, Asthma and Immunology (ACAAI). “Most people don’t want to give up the cat. Usually, they will remove me as the doctor before they remove the cat.”

Cat allergy is the most common animal allergy, affecting about one in five adults worldwide. Symptoms range from stuffy nose and itchy eyes, to hives, wheezing and asthma attacks.

Immunotherapy, often called allergy shots, can be effective in taming reactions in many people. But immunotherapy requires several years of injections, which many people don’t want to do.

The good news is that researchers are on the hunt for new treatments – and developing some promising new options. This article, fully updated for 2023, explores the novel therapies under study. They include a biologic medication that enhances allergy shots, and even a vaccine for kitty, designed to trim the volume of allergens that cats shed.  

And some relief may be as near as your local pet store. In 2020, Nestlé Purina began selling a cat food that neutralizes allergens in the cat’s saliva, a source of the protein that causes so much itchy, wheezy misery.

Cat Allergen: It’s Everywhere

The major culprit in cat allergies is “Fel d1,” a protein excreted in the cat’s skin, saliva, and urine. When cats lick themselves, they deposit Fel d1 on their fur. When the cat sheds, the allergens on the hair and dander (dried skin particles) spread.

And do they ever spread. Fel d1 proteins are small, so they remain suspended in the air. Fel d1 is also sticky, and takes a long time to decompose, Blaiss explains. The proteins cling to surfaces like draperies, carpets, furniture, bedding, clothing, and even walls.

Because of this, cat allergens are notoriously difficult to remove from a home, even with cleaning and vacuuming. Research has shown that there are cat proteins in almost all U.S. homes, even in homes where there are no cats. In schools, kids can bring in enough Fel d1 on their clothes and backpacks to trigger asthma symptoms in in their allergic classmates.

Bathing cats can cut down on Fel d1 in the fur, but only for a day or so. Studies have found female cats produce a lower level of allergens than males, while neutered males produce lower levels than unneutered males – but all produce plenty.

Current Cat Allergy Treatments 

If avoiding cats isn’t possible, or you just really, really want a cat despite an allergy, Blaiss recommends at a minimum to never allow the cat inside your bedroom, where you spend about eight hours a day.

Products such as antihistamines, nasal steroids and asthma medications can provide some relief. But medications treat symptoms, not the cat allergy itself. To do that, you need immunotherapy, which is given as shots at an allergist’s office.

Immunotherapy retrains the immune system to tolerate more cat protein without reacting. Typically, patients go to an allergist’s office for weekly injections with small amounts of cat protein during a buildup phase that lasts for several months. That’s followed by monthly “maintenance” injections for three to five years.

Research shows that cat immunotherapy can reduce symptoms in many people, and that the results last. But some people react to the injections, while others quit because of the inconvenience of as many as 80 injections in all.

“A lot of people quit before three years. There really is a need to get the duration of it down,” says Dr. Harold Nelson, an allergist at National Jewish Health in Denver.

Some allergists offer sublingual immunotherapy (SLIT), which uses liquid drops of cat extract placed under the tongue. But the U.S. FDA has not approved this treatment, so allergists offering it are doing so “off-label.” Nelson says that without clinical trials to confirm dosage and efficacy, there is no way for patients to know if the formulation has the right amount of cat protein to develop tolerance.

Using Lab-Created Antibodies

In the hunt for new treatments, one possibility researchers have been studying is using lab-created antibodies to neutralize or block immune system cells that drive allergic reactions.

A key step in IgE-mediated allergic reactions occurs when IgE antibodies in the bloodstream of people with allergies encounter their allergen, in this case, Fel d1. In a 2022 study, researchers created two versions of a protective type of antibody (IgG) developed by Regeneron Pharmaceuticals. The idea is that the monoclonal antibody blocks IgE from binding to the cat protein.

Over 50 participants with cat allergy and mild asthma got either a single shot of the IgG antibodies, or a placebo shot. The Phase 2 study found that the IgG antibodies prevented wheezing in the majority of participants when they were exposed to cat allergen in a special exposure chamber. Three months later, the single dose of antibodies continued to prevent some asthma symptoms, and participants were less reactive on cat allergen skin tests.

But plans for a larger clinical trial have fizzled. In late 2022, the company announced it was halting a Phase 3 study on the drug, citing “futility.” Regeneron did not provide further explanation.

Speeding Up Immunotherapy

A second monoclonal antibody approach, which uses the biologic medication tezepelumab, looks more promising.

In the CATNIP trial, researchers found that combining cat allergy shots with the biologic medication tezepelumab desensitizes those with cat allergies more quickly – and that the results may last even after the medication is stopped.

Tezepelumab blocks a chemical messenger called thymic stromal lymphopoietin (TSLP).  TSLP is found in the cells that line the nose, airways and elsewhere, and is involved with kick-starting and driving the allergic inflammatory response.

The study included 121 cat-allergic adults who were placed into one of four groups. One group received the tezepelumab and cat allergy shots. The other groups received either tezepelumab and placebo allergy shots, a placebo medication and real allergy shots, or placebos for both.  

In the blinded, controlled study, participants didn’t know whether their monthly dose of tezepelumab, given intravenously, or weekly cat allergy shots were real or a placebo.

Researchers then spritzed cat allergen extract up their noses at various point and measured nasal symptoms such as stuffiness and itchiness, along with levels of inflammatory molecules in their nasal secretions.    

After a year of treatment, the group who received tezepelumab plus immunotherapy had significantly fewer nasal symptoms than those who got allergy shots alone.

“The combination of immunotherapy and tezepelumab was significantly better than immunotherapy alone” at the one-year mark, says Dr. Jonathan Corren, the study leader. He’s an associate clinical professor of medicine at the school of medicine at University of California, Los Angeles.

And there are some indications the results may persist. One year after they stopped receiving either the biologic medication or the allergy shots, nasal symptoms continued to be reduced when exposed to cats.  “It looks like there is some degree of persistent tolerance when you combine the two,” Corren says.

When they analyzed participants’ nasal fluids, Corren and his colleagues found that tezepelumab had “very profound effects on mast cells,” down-regulating their signaling even one year after stopping treatment.

Corren notes that the CATNIP study was a “proof of concept,” using cat as a “model allergen” to test the effect of tezepelumab on TSLP and the allergic response. That means the effect of tezepelumab isn’t cat-specific, and the medication may help to desensitize to other allergens as well, he says.

Biologics: the Pricing Problem

Blaiss says the CATNIP findings are “exciting,” in that they show blocking “TSLP improves the efficacy of cat immunotherapy even a year after it was the tezepelumab was stopped.”

But a practical application for cat allergy sufferers doesn’t look imminent. At this time, the drugmaker Amgen isn’t pursuing tezepelumab specifically as a cat allergy treatment. Plus, biologic medications are pricey. 

However, tezepelumab (the brand Tezpire) was approved for use in the U.S. in 2021 to treat severe asthma in people ages 12 and older. Clinical trials found tezepelumab reduces the number of severe asthma flares. As well, it is being studied a treatment for chronic rhinosinusitis with nasal polyps and other conditions.

“I highly doubt any patient would pay out of pocket due to cost, or any insurance would cover as it would be off-label,” says Blaiss. “Of course, it could be used in severe uncontrolled asthma patients [with cat allergy] as that would be on-label as approved by the FDA,” he notes.

A Vaccine for Kitty

New Strategies for Controlling Cat Allergy. Little girl playing with cat in a table.
Photo: Getty

Here’s another option: Why not have the cat get the shots? Researchers in Switzerland are investigating whether a vaccine, called HypoCat, can be administered to felines to reduce their allergen load.

This vaccine uses a virus-like particle to provoke the cat’s immune system to immunize it against its own allergenic protein. The vaccine prompts the cat to develop antibodies that bind with and neutralize Fel d1. The idea is that this will reduce allergy symptoms in pet owners.

Researchers treated over 50 cats with the vaccine, administering it three times over the course of six weeks. Researchers found the vaccinated cats made antibodies to Fel d1, and had a reduction of Fel d1 in their tears. The study was published in the Journal of Allergy and Clinical Immunology in 2019.

A subsequent study also found that seven out of nine cat owners with vaccinated pets reported fewer allergy symptoms. As well, they could interact with their cats longer.

Importantly, interfering with Fel d1 doesn’t appear to have any health effects on the animal, says Gary Jennings, CEO of Saiba Animal Health, the vaccine developer. Some cats shed high levels of Fel d1, and other cats naturally produce very little, with no apparent health effects. To keep Fel d1 tamped down, cats would need a shot about every six months, he says.  

But availability of the vaccine is at least four to five years away, since more clinical trials are required. The company is also in the early stages of developing a dog allergen vaccine, HypoDog. In dogs, there are five or six major dog allergens, Jennings say, making this more complex.

Blaiss finds the approach promising. However, until there is a controlled study, he says the question remains as to whether symptom relief “is truly lasting.”

Cats with Gene Editing

If you search online, you might find some cats or breeds advertised as “hypoallergenic.” This is a myth. Although some cats produce less Fel d1 than others, there is no such thing as an allergen-free cat – yet.  

Researchers at InBio have used the gene-editing technology CRISPR to delete Fel d1 genes from cat cells in the lab. InBio’s goal isn’t to breed hypoallergenic cats, says researcher Nicole Brackett. Instead, the company is developing the science needed for an eventual gene therapy. The idea is to delete genes that encode for Fel d1 from the salivary and sweat glands of adult cats.

The research is in its early stages. There’s a big leap between deleting Fel d1 from cells in a lab to figuring out how to do it in an actual cat, Bracket says.

But she is motivated. She has both a cat and cat allergies, which she tames with antihistamines. “She’s worth it,” Brackett says of her feline.

Allergen-Reducing Cat Food  

As you await therapy developments, you may want to pick up a bag of Pro Plan LiveClear, sold by Nestlé Purina PetCare. According to the company, the new cat food is made using eggs that contain an anti-Fel d1 antibody. When cats nibble on the kibble, the egg powder binds to Fel d1 in the cat’s saliva, neutralizing it.

During grooming, the cat transfers less allergen onto its skin and fur, without altering the level of Fel d1 the cat produces. A study published in 2019 found that after 105 cats ate the allergen-reducing food for three weeks, they had 47 percent fewer allergens in their fur.

Blaiss says if you’re allergic to your cat, the cat food is probably worth a try. “My concern is that it doesn’t block Fel d1 100 percent. But is it enough to make a difference? That may depend on the person, how much the cat is producing and how sensitive you are.”  

The allergen-reducing kibble isn’t cheap. It’s about four times more expensive than typical cat food – and cats needs to eat it every day. But online reviews are largely glowing. Many allergic cat owners say that a few weeks after switching to LiveClear, they are able to snuggle with their cat without a sniffle.

And while Fel d1 is the main driver of cat allergies, it isn’t the only one. Cats excrete several other proteins that allergic individuals may become sensitized to. So the cat food – and any treatments targeting Fel d1 – may not get rid of allergy symptoms completely.

With people increasingly working remotely and relying on pets as a balm for loneliness, Nelson observes that the need for better cat allergy treatments is more urgent today. “Within homes, people are being exposed to even more cat allergen than ever,” he says.  

Related Reading:
Can Cat Allergy Develop as an Adult?
Early Life Exposure to Pets and Pests May Influence Asthma Development
Why “Pet-Free” College Housing Isn’t What It Seems