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Peanut Vaccine on the Horizon

As the growing ranks of the food-allergic know all too well, the only treatment for food allergies is strict avoidance of your allergens. But researchers are toiling in labs around the globe to develop therapies with the goal of desensitizing the allergic.

New research out of Australia holds great promise. A study team announced in December, 2010 that they had discovered fragments of peanut protein that may be the key component to a peanut vaccine that could be given by injection.

Allergic Living’s Lisa Ferlaino spoke with Dr. Robyn O’Hehir, the team’s leader and a professor of allergy and immunology at Monash University in Australia, about the discovery and what it means.

Why the focus on immunotherapy as a treatment for peanut allergy?

“Allergen immunotherapy is the only treatment that can actually change the natural course of allergic diseases. We know from the aero-allergens such as house dust mites and grass pollens, and even from bee and wasp venom, that allergy shots make a big difference in people’s lives. That’s what we’re striving for.

We also know that peanut allergy is becoming more common worldwide, and that people find traces of peanut in unexpected foods. That’s one of the reasons avoidance isn’t really sufficient.”

Peanuts have long been viewed as too risky for immunotherapy, too likely to provoke anaphylaxis. How do you address that?

“By studying the white blood cells of patients with peanut allergy, we’ve been able to narrow down the core epitopes – the critical fragments of peanut protein that drive the allergic response in people with peanut allergy – and we’ve identified ones that are too small to cause anaphylaxis. They won’t bind to IgE [allergy antibodies], but they’re big enough to kickstart the immune system to develop tolerance.”

Are these fragments parts of peanut’s infamous Ara h 1 and Ara h 2 proteins?

“Yes. We’ve identified the critical peptides [protein fragments] in Ara h 2, the major peanut allergen. That’s the one most associated with anaphylaxis. Ara h 1 is also important, and we’re well on the way to identifying the critical peptides in it, too.”

There are a few peanut therapies in the works. Is your research unique?

“There’s a lot of research in animal models [using mice], but our research looks at human white blood cells. That’s important, because peanut allergy is not a natural condition for mice.”

Next Page: More questions on the vaccine

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If the clinical trials are successful, will this immunotherapy cure a child’s peanut allergy?

“The idea here is to induce immunological tolerance. So what you’re doing is switching the immune response of the individual away from that of an allergic individual to behave more like that of a non-allergic individual. Although ‘cure’ is a difficult word, that is essentially the goal.”

How would the vaccine work? For instance, I’m peanut allergic. Would I get a one-time shot?

“I envisage that you would receive three to six injections.”

There are studies in which children were given small, increasing amounts of peanut flour to consume. The studies have been largely successful, but some participants had reactions before succeeding with tolerance.

“We have a completely different approach. The biggest difference between our vaccine and the oral food allergy therapy research is that feeding the daily peanut flour can be associated with unpleasant side effects, and it doesn’t seem to induce long-lasting tolerance. Our vaccine is looking to change the immune response and to induce immunological tolerance that is long lasting. And ours doesn’t require daily feeding with peanut. The reason we’re sort of giddy with excitement is that we’ve found that each of the subjects’ [immune systems] recognized one or more of our candidate peptides. That’s why we’re confident that one vaccine will work in all patients with peanut allergy.”

The possibility of a peanut vaccine is truly exciting. What are the next steps?

“First, we need to get the GMP peptides [synthesized, purified peptides adhering to good manufacturing practices], which we should have in about three years; then toxicology studies, which take 18 months; then we could begin the early-phase clinical testing.”

In the hunt for a peanut allergy treatment, there is your work, the oral immunotherapy studies, heat-killed bacteria vaccine studies and so on. Is this a bit of a race to the best solution?

“It’s not so much a race. The research is more of a team effort, not a competition. We all want to find a treatment for this very alarming and growing problem.”