The safety profile of a drug under consideration for Food and Drug Administration approval in peanut allergy will be a particular area of focus later this week when a panel of outside experts convened by the agency meets to discuss it.
The FDA’s Allergenic Products Advisory Committee, or APAC, will meet Friday to determine whether or not to recommend FDA approval of the drug, Palforzia, or AR101, developed by Brisbane, California-based Aimmune Therapeutics. A briefing document posted on the agency’s website pointed to a higher rate of patients in the treatment arm of the Phase III study being used for approval experiencing systemic allergic reactions – including ones that required treatment with epinephrine – than those in the placebo arm. The FDA usually follows AdCom recommendations, but is not bound by them.
Shares of Aimmune were up more than 11 percent on the Nasdaq Wednesday afternoon. Aimmune did not immediately provide comment.
The Phase III study, known as PALISADE or ARC003, met its primary endpoint, with a majority of patients who received the drug being able to ingest 600mg of peanut protein with no more than mild symptoms. Moreover, while it was not considered part of the primary endpoint, adverse events related to patient-reported accidental exposure among those in the treatment group decreased from 11.5 percent during the up-dosing period to 9 percent during maintenance, suggesting that Palforzia can protect against allergic reactions stemming from accidental exposure to peanuts. By contrast, incidence of those events did not change in the placebo group.
On the other hand, the study showed an increase in systemic allergic reactions among patients in the treatment group compared with those receiving placebo, which in some cases required patients to use epinephrine. During initial dose escalation and up-dosing, 9.4 percent of patients taking Palforzia reported systemic allergic reactions, compared with 3.8 percent of those taking placebo, while rates of those who required epinephrine were 6.1 percent and 3.1 percent, respectively. In the maintenance period, 6.1 percent of patients on Palforzia used epinephrine to treat a systemic allergic reaction, compared with 1.7 percent of those in the placebo arm, while the treatment arm also saw a substantial dropout rate compared with those on placebo.
Explaining the disparity in allergic reactions, a pediatric allergy expert said that it will take time for patients on the drug to build up their ability to tolerate peanut exposure.
“This slowly changes your tolerance over time to something you’re already allergic to, so you’re going to have allergic reactions while you’re building up,” said Dr. Russell Hopp, professor of pediatric allergy at the University of Nebraska Medical Center, in a phone interview. Hopp did not take part in the clinical studies of Palforzia.
Hopp compared the process to what would happen if somebody with an allergy to cats wanted to move in with a significant other who had a pet cat. Over time, he said, the person would experience allergic reactions, but would gradually be able to tolerate a greater number of visits.
Nevertheless, while expressing enthusiasm about the drug, Hopp said it has limits and should not be regarded as a complete cure for peanut allergy. Palforzia’s main utility will be to protect patients against accidental exposure to peanut allergen.
“I think this is a product that has limited potential for extremely motivated families who have extensive amounts of time and limited expectations of the final outcome,” he said.
The drug has faced criticism before. In July, the Institute for Clinical and Economic Review stated in a report that neither Palforzia nor a potential competing product, DBV Technologies’ Viaskin Peanut, had enough evidence to show that it yielded a net benefit better than strictly avoiding peanuts altogether. Aimmune and the Asthma and Allergy Foundation of America both criticized the report. DBV withdrew its FDA approval application in December 2018 and plans to resubmit it later this year.
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