LINDY ALEXANDER
Australian researchers have made a significant breakthrough in the long-lasting treatment of peanut allergy, writes Lindy Alexander.
Olivia was two-and-a-half years old when she took a bite out of a peanut butter sandwich. Even without swallowing, Olivia’s lip started swelling. “We immediately knew something was wrong,” says her mother, 48-year-old Tanya May. The family’s GP referred Olivia to an allergist who conducted tests for a range of reactions. The news was delivered bluntly. “The allergist told us that Olivia was probably anaphylactic and that she needed to avoid peanuts,” says May. “We were told to go home and empty out the pantry of anything containing nuts. And that would be it for the rest of Olivia’s life.”
Peanut allergies affect 3 per cent of Australian children under one, and the life of a parent with such a child can be taxing to say the least. There’s the hypervigilance around ensuring that any food the child puts near their mouth isn’t going to spark an anaphylactic reaction. But there are also the subtler societal impacts. “I had four kids under five years of age and we’d go to play centres and when it came to signing the kids in, often Olivia wouldn’t be allowed to play because the person who had anaphylaxis training wasn’t in that day, or they didn’t accept kids like that,” May says. “There was also all the paperwork that we needed to fill out for school, with a photo of Olivia on it, getting the doctors to sign it, sending it to the hospital for them to sign and then send back. There were so many logistical things that took time and effort.”
Thinking ahead and preparation were also a big thing for May. When Olivia was at kindergarten, May would have to provide alternative treats for her because she couldn’t share children’s birthday cakes or goodies. “Even though the kindergarten was a nut-free zone, we didn’t take the risk of her sharing food. I was not very good at that. Olivia would come home and tell me that they had had a party and that she couldn’t eat anything. I’d feel absolutely terrible.”
Despite the stress involved, May was dedicated to ensuring that her daughter was never placed at any risk and accepted that her caution would be a lifelong commitment. When Olivia was three years old, May saw a notice in her local health centre for a peanut allergy trial. Coming from a family of scientists, May felt compelled to take part. “I like to be a member of the community and to do the right thing,” she says. “Helping people was my motivation.”
The trial was led by Professor Mimi Tang of the Murdoch Children’s Research Institute in Melbourne, and was based on a novel treatment that combined probiotics (containing live bacteria) with peanut oral immunotherapy for treating peanut allergy. Immunotherapy has two outcomes – the first is to desensitise and the second is to induce remission. Sixtytwo children aged between one and 10 were involved in the trial, and half were randomised to receive the probiotic peanut therapy and the other half randomised to receive the placebo.
Olivia went to the hospital for a “rush day” where she was given eight doses of peanut in increasing amounts. “The children started at less than a thousandth of a peanut and they got to approximately a tenth of a peanut on the first day,” says Tang.
The treatment lasted 18 months, with parents giving the peanut protein and probiotic to their child each day and every two weeks coming back to the hospital for researchers to increase the dose until it was about 16 peanuts. “Olivia was a trouper, really, when you think about what she went through,” May says. “She had to have a cannula put in every time just in case they needed to administer adrenalin. It was pretty harrowing for everybody.”
After the treatment was complete, Tang and her team waited a further month before challenging the children to see if they had developed a tolerance to peanuts. The results were astonishing. Eighty-two per cent of the children who received the probiotic peanut therapy developed “sustained unresponsiveness”, meaning they could now tolerate peanuts. “At that time they did not appear to have the allergy,” says Tang, of the successful participants. “So we sent them home and told them to incorporate peanuts as part of their normal diet.”
Four years later, Tang and her team followed up with the participants. “If you look at the total group of all the children who received the probiotic peanut therapy, two-thirds were still eating peanuts in their diet,” says Tang. “That’s compared to only 4 per cent in the placebo group.”
The children were also tested for tolerance, where they were asked to stop eating peanuts for eight weeks before having peanuts again to see if they were still in remission of their allergy. More than half retained their tolerance.
Of the children who gained initial tolerance after treatment, 80 per cent were still eating peanuts four years later. “Seventy per cent passed the challenge, showing long-term remission of their allergy,” Tang says.
Tang emphasises that this is not a cure for peanut allergy. “What we are saying is that it appears this treatment can induce long-lasting remission of allergy years after stopping treatment. The scientific community calls this ‘sustained unresponsiveness’.”
The key may lie in the coupling of the peanut protein with a probiotic. “Many other researchers are looking at just the peanut protein on its own, and it’s clear this is good at suppressing allergic reactions by exhausting the allergic response,” Tang says. “But in the vast majority of studies only a small subset of participants achieved this remission state or sustained unresponsiveness.” Tang believes this is because the immune system struggles to change the way it responds to an allergen when it’s already been programmed to react to that allergen.
Tang selected a probiotic – lactobacillus rhamnosus – known to be supportive of tolerance-like responses. By putting it together with the peanut protein, she was hoping the probiotic would induce an environment that encourages the immune system to respond with tolerance rather than allergy when it came across the peanut protein. “Giving the peanut and the probiotic together gives a signal to the immune system that says, ‘Try a different response, try tolerance.’ ”
What is promising, says Tang, is that so many children have showed sustained unresponsiveness to peanuts. “It’s not just by the time they finish treatment, but years after they’ve stopped treatment that remission is maintained. We’re excited.”
But she is keeping her enthusiasm in check. While the findings are remarkable, they need to be reproduced on a larger scale, tested with adults and other age groups and with other foods. “There’s a lot of work to be done,” Tang says. “But we hope [eventually] to develop a product so it is available to everyone in the world who has a peanut allergy.” That’s no small feat given about
250 million people worldwide have a peanut allergy.
Olivia, now 10 years old, eats peanuts freely in her diet. “She doesn’t like them – not the smell or the taste – but she doesn’t get any reaction if she eats them,” May says. When Olivia finished the trial, her parents wanted to maintain her tolerance and have administered a handful of peanut M&Ms to Olivia each weekend.
“She has them like medicine,” May says, laughing. “But it’s been amazing, and I’m so grateful that we had the opportunity to be in the study.”
For children such as Olivia, the impact of the trial has been life changing. “These children can go to restaurants that they couldn’t go to before, travel to countries they weren’t able to before,” Tang says. “It’s changed their lives completely. Not just the patients, but
• the families as well.”