Peanut oral immunotherapy in a capsule is close to approval, bringing hope — not of a cure — but of lives lived with less vulnerability.
FOR MORE than seven years, Alex lived like most kids with peanut allergies: he strictly avoided the legumes. His mom, Sarah Thomas, read food labels, grilled restaurant staff, and sent safe cupcakes for Alex to eat at birthday parties. When Alex was young, Thomas heard about oral immunotherapy experiments, in which allergists were attempting to retrain the immune system to tolerate peanuts by feeding patients gradually increasing amounts of the allergen. But they were taking place at Duke University in North Carolina, more than three hours away from their home in Chesapeake, Virginia. She recalls putting her son on a waiting list, but it was realistically too far to go for treatment.
Then, when Alex was 9, the family moved to southern California, met their new allergist, and learned that she was also conducting peanut oral immunotherapy trials. This time, however, the studies weren’t being done for academic purposes. A company called Allergen Research Corp. was developing a standardized treatment that the founders hoped would be approved by the Food and Drug Administration. Alex had the opportunity to take part in one of the trials of a Phase 2 clinical study of what is essentially a new drug regimen – featuring carefully calibrated dosages of peanut proteins.
At first, Alex was in the group placed on a placebo (although his family didn’t know that), but after six months, he was moved onto treatment. Over six months, the boy was able to consume 300 milligrams (mg) of peanut protein, then succeeded at passing a challenge at 443 mg, or about one and a half peanuts. (Alex is now in a continuation of the study.)
As Alex and the rest of the people in this study (it initially enrolled 55 patients aged 4 to 21 at eight locations) continue to be monitored, the company, which has changed its name to Aimmune Therapeutics, is moving on to a large-scale Phase 3 trial. At press time, the researchers were busily working to recruit 500 patients, ages 4 to 55, to participate in about 60 study sites in the United States, Canada and Europe.
“What we’re trying to do is to take patients who are at risk from accidental exposure to even really small amounts of peanut protein and get them to a level of desensitization where they are protected against accidental exposure,” explains Stephen Dilly, Aimmune’s CEO.
If all goes well with the Phase 3 trials, by 2018, there could finally be an FDA-approved, widely available treatment for peanut allergy, the modern-day epidemic that tripled in size among U.S. children between 1997 and 2008. While not a cure, the aim of this standardized OIT regime is to make patients significantly less allergic to peanuts – and greatly reduce the odds of life-threatening anaphylaxis from an accident with food, whether at a restaurant, a friend’s home – or even in the allergic person’s own kitchen.
RESEARCHERS have been devising theories of how oral immunotherapy could work for more than a decade. It is peanut allergic kids – whose parents will do almost anything to decrease their worry that one wrong bite could have severe consequences — who have been the guinea pigs. As successes emerged, some allergists started doing OIT, privately, in their clinics, while other leaders in the field cautioned this was premature, that there was still a lot to learn about how and for whom the desensitization therapy works best. There were treatment risks: patients sometimes experienced stomach pains or hives and in some cases needed epinephrine to stop allergic reactions.
Then in 2011, the allergy group Food Allergy Initiative (now FARE) hosted a research retreat with more than 40 researchers, government officials and industry and advocacy leaders. Out of that, a mission became clear: OIT had the potential to help the millions with food allergies, but for them to have safe access to it, large-scale research needed to happen. From there, Allergen Research Corp., which later turned into Aimmune, was formed.
“We’ve stood on the shoulders of people who have been working in this field for a long time and come up with what we found to be the best in dosing protocols out there,” says Dilly, who has a background of bringing pharmaceutical treatments to market.
There are some clear differences between Aimmune’s process, and what other OIT trials and private OIT practitioners are doing. For one, rather than using off-the-shelf peanut flour, the new treatment, called AR101, uses peanut flour with a very consistent level of protein, which is precisely analyzed for a protein signature based on three key allergenic proteins.
Considered a biologic drug, AR101 is produced in a facility in Clearwater, Florida, with strict quality control. The company’s formula, which contains all of the peanut proteins, is put into a capsule at a fixed ratio. The patient breaks the capsule open and mixes the contents into food – such as apple sauce, Sunbutter or ketchup. It’s a standardized treatment: each patient starts on the same dose and is built up at the same pace, with increases usually every two weeks, until the person reaches 300 mg of protein. Then, you stay on a maintenance dose – forever – to maintain the level of desensitization.
AR101 capsules lined up by dose size. From left: 0.5 milligrams, 1 mg, 10 mg, 20 mg and 100 mg.
For maintenance, there are 300 mg sachets.
The FDA has granted Aimmune its “Breakthrough Therapy Designation,” which means it walks with the company side-by-side throughout the development process. “We are in constant dialogue with the FDA,” says Dilly. “We’re doing something new here, which is taking something that’s grown in the ground and turning it into an FDA-regulated biologic.”
Another key difference between Aimmune’s lastest version of AR101 oral immunotherapy and other regimens is that in the build-up and maintenance phase, you’re never taking a daily dose higher than 300 mg of peanut (approximately one peanut). Dilly contends this design improves safety, while still providing a good level of desensitization.
In early March 2016 at the AAAAI allergists’ conference, Aimmune released final results from its Phase 2 study, as well as from continuations of that research. Out of 55 original participants, including young Alex, 40 completed the up-dosing to 300 mg and maintenance dosing of 300 mg. All of them were able to tolerate 443 mg, or about one and a half peanuts, 90 percent were able to tolerate 1,043 mg, which equals about four or five peanuts, and 60 percent were able to safely consume 2,043 mg of peanuts – which is two grams. “We’re in that range of real clinical relevance that can impact daily life, quality of life and the ability to have a normal childhood,” says Dilly.
And what happened to the other 15 participants? Eleven of them dropped out because of gastrointestinal issues, typically a dull ache in the gut. (One person also had a more serious reaction requiring epinephrine and others left due to compliance and scheduling issues). Dr. Brian Vickery, an assistant professor of pediatrics at the University of North Carolina-Chapel Hill who also works at Aimmune part-time, says the results are in line with what has been seen in other OIT studies, and indicates that for some patients, oral immunotherapy just won’t be effective. “This will be something that will work in about four patients out of five,” adds Dilly. “The good news is if it’s not going to work, it declares itself early.”
THE QUESTION IS, if treatment with AR101 ensures you can tolerate a peanut and a half, is it enough of a benefit for patients to go through the hoops, stressful moments, and time commitment of treatment, as well as taking a dose every day for the rest of their lives?
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