The First Peanut Allergy Drug Might Be Approved Soon In America, But Not Without Controversy

Photo: A granel, Wikimedia Commons

On Saturday, a panel of experts assembled by the U.S. Food and Drug Administration voted that the agency should approve a drug called Palforzia designed to help people manage their peanut allergy. But the non-unanimous verdict rendered by the panel highlights the ongoing debate over whether this therapy, a pill containing peanut protein, is actually worthwhile for patients to take.

The treatment is known as oral immunotherapy, and it works by purposefully exposing someone to a tiny amount of the allergen, with the hope that small doses given over a long enough time can desensitise the person’s hyperactive immune system.

You could use pretty much anything containing peanuts, including peanut butter, for this immunotherapy. But for years, American pharmaceutical companies have been trying to get products to the market that would be formally approved by the Food and Drug Administration. The furthest along of these drug candidates is Palforzia, developed by the California-based Aimmune Therapeutics. The drug essentially just contains a tiny dollop of peanut flour.

Before the FDA approves any new drug, it typically brings together an advisory committee of outside experts to look at the relevant clinical trial results and vote on whether it should be approved based on the overall data. Their recommendations aren’t sacrosanct, but the FDA rarely goes against them.

At first glance, the results of the clinical trials submitted by Aimmune are certainly impressive. In the largest trial, involving over 550 people between the ages of 4 and 55 years old, two-thirds of patients who took Palforzia for a year — which included a maintenance period of six months where people took less of it — were able to withstand 600 milligrams of peanut protein without experiencing major side effects, while only 4 per cent of the placebo group did the same.

Many of those who continued taking Palforzia as part of another trial were then shown to tolerate even higher doses, up to 2000 milligrams. In some studies, up to a third of people could be exposed to peanut without experiencing any symptoms at all.

These numbers sound impressive, but 600 milligrams is roughly two to three actual peanuts. So while the treatment might help people avoid an accidental reaction brought on by eating food laced with peanuts, it isn’t a cure.

What’s more, there were some safety risks noticed during these studies. Over 10 per cent of people taking Palforzia discontinued the treatment, often because they couldn’t stand the side-effects they experienced. These side-effects included anaphylaxis, a systemic allergic reaction that can be fatal if not treated immediately with a dose of epinephrine. Compared to the control group, people taking the drug experienced more discontinuations, anaphylaxis, and a chronic inflammatory condition that injures the esophagus called eosinophilic esophagitis, even though both groups were told to avoid peanuts as usual.

Outside researchers have documented these risks, seen across many clinical trials of peanut oral immunotherapy. And given that people are taking the treatment to avoid severe allergic reactions, some have argued that the risks might outweigh the benefits. It was that same rationale that led two of the nine voting experts to recommend against approving the drug.

“I think few people would think of anaphylaxis as a benign condition,” said John Kelso, an allergist at Scripps Clinic in California and one of the dissenters, during the panel’s discussion of the study data. Later, following the vote, he stated, “This is not the answer.”

The FDA has said that if it did ultimately approve Palforzia, it would only do so by carefully regulating its use — a caveat affixed to some drugs that’s known as a Risk Evaluation and Mitigation Strategy (REMS). For Palforzia, that would include mandating that every person taking Palforzia also have an existing supply of epinephrine, and that any increase in dose, including the first one, is provided in an approved medical clinic. Eight of the experts voted yes for approving Palforzia if REMS is implemented alongside it, while Kelso remained the sole “no.”

The president of the American Academy of Allergy, Asthma and Immunology supported the panel’s decision, according to a statement it released today. “After today’s meeting, we are another step closer to having the first FDA approved therapy for peanut allergy; this is truly a groundbreaking development. Patients and their families have been waiting for this for many years and will be eagerly awaiting the FDA’s final decision,” AAAAI President David M. Lang said in the statement.

Should the FDA agree with the panel’s decision, it would approve the drug by early next year. But even leaving aside the debate over its effectiveness, some might side-eye its potential price tag — an analysis by the nonprofit organisation ICER published this June estimated that the treatment might cost $US4,200 ($6,117) a year. Their panel of experts concluded that Palforzia wasn’t superior, at least given the current evidence, to simply avoiding peanuts as usual.

Editor's Note: Given Australia's strict standards for available medicines, it's unlikely that this drug will be approved on our shores, but it does present an interesting leap for peanut allergy sufferers.

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