For alpha-gal patients, allergy drug could cut the severity of reactions to red meat

There’s emerging evidence that the allergy drug omalizumab may reduce severe allergic reactions for alpha-gal syndrome, a red meat allergy triggered by a tick bite.

In a study presented Thursday at the annual meeting of the American College of Allergy, Asthma and Immunology, researchers found that 95% of participants using the drug experienced meaningful reductions in the frequency or severity of their allergic reactions. The study included 64 people with confirmed alpha-gal diagnoses who took omalizumab for an average of 23 months. The findings haven’t yet been published in a peer-reviewed journal.

Alpha-gal syndrome is predominantly associated with the lone star tick. When the tick feeds on mammals like cows, deer, pigs and goats, it can pick up a sugar molecule in their blood called alpha gal. When the tick goes on to bite a human, it can transmit that sugar, which, in some people, can trigger an allergic reaction to red meat and, in some cases, gelatin and dairy products.

The allergic reactions can range in severity, from hives to severe stomach pain to life-threatening anaphylaxis, among other symptoms. Because of that, doctors typically advise patients to avoid red meat and meat-based soups and gravies, as well as to consider avoiding gelatin or dairy.

Omalizumab (brand name: Xolair) is already approved for people with severe food allergies, including peanut, egg and dairy allergies. It works by targeting immunoglobulin E (IgE), the antibody that drives allergic reactions, and removing it from the bloodstream.

“If you have less IgE, it’s going to take a much higher dose of an allergen to trigger a reaction,” said Dr. Erin McGintee, an allergy and immunology specialist at ENT & Allergy Associates and Stony Brook Medicine tick-borne disease adviser.

The drug isn’t a cure for food allergies, and people taking it still need to avoid the foods they are allergic to. Instead, it acts like a safety layer, reducing what could be a severe, life-threatening reaction to something more manageable if a person accidentally eats the allergy-causing food.

Candice Matthis, 46, of Charlottesville, Virginia, was diagnosed with alpha-gal syndrome in 2019 after 12 years of symptoms.

“I wasn’t aware of alpha gal at the time,” said Matthis, who later co-founded the nonprofit Alpha-Gal Foundation. “I never even asked, because it was just such an inconsistent reaction. I could eat steak or dairy and not have a reaction. A lot of people deal with that — they may have a reaction once and not the next time — so it’s hard to draw a correlation with this allergy.”

Matthis, who wasn’t part of the new study, was prescribed omalizumab for other food allergies. She has been taking it for a year and said she has seen substantial improvement.

“It’s definitely helped with my reactivity,” she said. “I accidentally drank milk at Starbucks. They put whole milk in my coffee instead of oat milk, and I took a big sip of it. My stomach hurt a little bit, but I didn’t have anaphylaxis.”

Dr. Collette Tilly, an allergy and immunology fellow at the University of North Carolina at Chapel Hill who led the study, said, “Our findings suggest that omalizumab may offer an important additional option for patients who continue to experience reactions.”

McGintee, who wasn’t involved with the study, called the new data “really exciting and encouraging.” However, she cautioned against using omalizumab inappropriately, for example as a means of enabling alpha-gal patients to be able to eat red meat again.

“This is a pharmaceutical product that’s not inexpensive,” she said. “The purpose of it is to keep people safe and prevent life-threatening allergic reactions. I think there’s kind of an important distinction there.”

Eight people in the study were able to fully incorporate red meat into their diets again, but Tilly cautioned against interpreting this as evidence that omalizumab can lead to remission of alpha-gal syndrome. Some patients do experience naturally declining alpha-gal IgE levels over time, she said.

“It remains unclear whether omalizumab increased reaction thresholds, facilitated reintroduction in patients whose sensitivity was already waning, or both,” she said.

It wasn’t possible, Tilly said, to determine whether those eight individuals had truly regained tolerance to red meat, as to assess that they would need to continue eating red meat after the drug would need to be discontinued. This was not examined in the study.

Dr. Supinda Bunyavanich, a professor in allergy and systems biology at Mount Sinai Health System in New York City, said the study’s findings were based on a retrospective analysis, and she called for a full clinical trial to be carried out with the drug.

“If it were shown in a prospective trial to help reduce sensitivity [to red meat], I think that would go a long way in terms of improving the lives and the safety of people who live with alpha-gal syndrome,” Bunyavanich said.

However, Tilly said an omalizumab trial would be ideal and is very much needed to identify which patients are likeliest to benefit, as well as the optimal treatment duration and dosing strategies. But persuading people to take part in such a study would be highly challenging. That’s because such a study would be likely to require deliberate food challenges in which the participants would be required to ingest red meat, and they would need to be monitored for many hours before they could be discharged. “They’d be committed to a full day in the clinic,” she said.

In the meantime, McGintee suggested, omalizumab could best be used on a temporary basis in patients who have severe reactions, in which blood testing reveals very high levels of IgE antibodies against alpha gal.

The need for new treatment options is particularly pressing, as cases of alpha-gal syndrome are on the rise in the U.S., driven by shifting patterns in the distribution of ticks. A study carried out this year by the Centers for Disease Control and Prevention found that an estimated 24% of adults who live in five states where lone star ticks are prevalent had antibodies to alpha gal, suggesting that they had been bitten by ticks and exposed to the molecule at some point.

McGintee and Bunyavanich described having witnessed increasing numbers of positive cases in their practices.

“It used to be something that would be mostly seen by our colleagues who practice in the Southeast or South, but we are increasingly seeing it now,” Bunyavanich said.

McGintee said one of the best things alpha-gal patients can do is take measures to avoid subsequent tick bites. “If a patient can avoid that, their allergy tends to get better over time anyway,” she said.

Lone star ticks are most active in the late spring, early summer and early fall.

“At those times, people should be using tick repellents both on their skin and on their clothing,” McGintee said. “They should be used anytime someone is putting themselves in a situation where they might have tick exposure, and that can be walking in the woods, mowing your lawn, going golfing or hiking, especially if you’re spending time in an area where small rodents and deer are also spending time.”